A deadlock flaw was found in the Linux kernel’s BPF subsystem. This flaw allows a local user to potentially crash the system.

Array index overflow in the xfrm_sk_policy_insert function in xfrm_user.c in Linux kernel 2.6 allows local users to cause a denial of service (oops or deadlock) and possibly execute arbitrary code via a p->dir value that is larger than XFRM_POLICY_OUT, which is used as an index in the sock->sk_policy array.

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix deadlock in nilfs_count_free_blocks() A semaphore deadlock can occur if nilfs_get_block() detects metadata corruption while locating data blocks and a superblock writeback occurs at the same time: task 1 task 2 ------ ------ * A file operation * nilfs_truncate() nilfs_get_block() down_read(rwsem A) <-- nilfs_bmap_lookup_contig() ... generic_shutdown_super() nilfs_put_super() * Prepare to write superblock * down_write(rwsem B) <-- nilfs_cleanup_super() * Detect b-tree corruption * nilfs_set_log_cursor() nilfs_bmap_convert_error() nilfs_count_free_blocks() __nilfs_error() down_read(rwsem A) <-- nilfs_set_error() down_write(rwsem B) <-- *** DEADLOCK *** Here, nilfs_get_block() readlocks rwsem A (= NILFS_MDT(dat_inode)->mi_sem) and then calls nilfs_bmap_lookup_contig(), but if it fails due to metadata corruption, __nilfs_error() is called from nilfs_bmap_convert_error() inside the lock section. Since __nilfs_error() calls nilfs_set_error() unless the filesystem is read-only and nilfs_set_error() attempts to writelock rwsem B (= nilfs->ns_sem) to write back superblock exclusively, hierarchical lock acquisition occurs in the order rwsem A -> rwsem B. Now, if another task starts updating the superblock, it may writelock rwsem B during the lock sequence above, and can deadlock trying to readlock rwsem A in nilfs_count_free_blocks(). However, there is actually no need to take rwsem A in nilfs_count_free_blocks() because it, within the lock section, only reads a single integer data on a shared struct with nilfs_sufile_get_ncleansegs(). This has been the case after commit aa474a220180 ("nilfs2: add local variable to cache the number of clean segments"), that is, even before this bug was introduced. So, this resolves the deadlock problem by just not taking the semaphore in nilfs_count_free_blocks().

In the Linux kernel, the following vulnerability has been resolved: tty: fix deadlock caused by calling printk() under tty_port->lock pty_write() invokes kmalloc() which may invoke a normal printk() to print failure message. This can cause a deadlock in the scenario reported by syz-bot below: CPU0 CPU1 CPU2 ---- ---- ---- lock(console_owner); lock(&port_lock_key); lock(&port->lock); lock(&port_lock_key); lock(&port->lock); lock(console_owner); As commit dbdda842fe96 ("printk: Add console owner and waiter logic to load balance console writes") said, such deadlock can be prevented by using printk_deferred() in kmalloc() (which is invoked in the section guarded by the port->lock). But there are too many printk() on the kmalloc() path, and kmalloc() can be called from anywhere, so changing printk() to printk_deferred() is too complicated and inelegant. Therefore, this patch chooses to specify __GFP_NOWARN to kmalloc(), so that printk() will not be called, and this deadlock problem can be avoided. Syzbot reported the following lockdep error: ====================================================== WARNING: possible circular locking dependency detected 5.4.143-00237-g08ccc19a-dirty #10 Not tainted ------------------------------------------------------ syz-executor.4/29420 is trying to acquire lock: ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1752 [inline] ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: vprintk_emit+0x2ca/0x470 kernel/printk/printk.c:2023 but task is already holding lock: ffff8880119c9158 (&port->lock){-.-.}-{2:2}, at: pty_write+0xf4/0x1f0 drivers/tty/pty.c:120 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&port->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 tty_port_tty_get drivers/tty/tty_port.c:288 [inline] <-- lock(&port->lock); tty_port_default_wakeup+0x1d/0xb0 drivers/tty/tty_port.c:47 serial8250_tx_chars+0x530/0xa80 drivers/tty/serial/8250/8250_port.c:1767 serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1854 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1827 [inline] <-- lock(&port_lock_key); serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1870 serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x109/0xa50 kernel/irq/handle.c:156 [...] -> #1 (&port_lock_key){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 serial8250_console_write+0x184/0xa40 drivers/tty/serial/8250/8250_port.c:3198 <-- lock(&port_lock_key); call_console_drivers kernel/printk/printk.c:1819 [inline] console_unlock+0x8cb/0xd00 kernel/printk/printk.c:2504 vprintk_emit+0x1b5/0x470 kernel/printk/printk.c:2024 <-- lock(console_owner); vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 printk+0xba/0xed kernel/printk/printk.c:2084 register_console+0x8b3/0xc10 kernel/printk/printk.c:2829 univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:681 console_init+0x49d/0x6d3 kernel/printk/printk.c:2915 start_kernel+0x5e9/0x879 init/main.c:713 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 -> #0 (console_owner){....}-{0:0}: [...] lock_acquire+0x127/0x340 kernel/locking/lockdep.c:4734 console_trylock_spinning kernel/printk/printk.c:1773 ---truncated---

In the Linux kernel, the following vulnerability has been resolved: NFSv4: Don't hold the layoutget locks across multiple RPC calls When doing layoutget as part of the open() compound, we have to be careful to release the layout locks before we can call any further RPC calls, such as setattr(). The reason is that those calls could trigger a recall, which could deadlock.

In the Linux kernel, the following vulnerability has been resolved: tracing: Fix sleeping function called from invalid context on RT kernel When setting bootparams="trace_event=initcall:initcall_start tp_printk=1" in the cmdline, the output_printk() was called, and the spin_lock_irqsave() was called in the atomic and irq disable interrupt context suitation. On the PREEMPT_RT kernel, these locks are replaced with sleepable rt-spinlock, so the stack calltrace will be triggered. Fix it by raw_spin_lock_irqsave when PREEMPT_RT and "trace_event=initcall:initcall_start tp_printk=1" enabled. BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper/0 preempt_count: 2, expected: 0 RCU nest depth: 0, expected: 0 Preemption disabled at: [<ffffffff8992303e>] try_to_wake_up+0x7e/0xba0 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.17.1-rt17+ #19 34c5812404187a875f32bee7977f7367f9679ea7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x60/0x8c dump_stack+0x10/0x12 __might_resched.cold+0x11d/0x155 rt_spin_lock+0x40/0x70 trace_event_buffer_commit+0x2fa/0x4c0 ? map_vsyscall+0x93/0x93 trace_event_raw_event_initcall_start+0xbe/0x110 ? perf_trace_initcall_finish+0x210/0x210 ? probe_sched_wakeup+0x34/0x40 ? ttwu_do_wakeup+0xda/0x310 ? trace_hardirqs_on+0x35/0x170 ? map_vsyscall+0x93/0x93 do_one_initcall+0x217/0x3c0 ? trace_event_raw_event_initcall_level+0x170/0x170 ? push_cpu_stop+0x400/0x400 ? cblist_init_generic+0x241/0x290 kernel_init_freeable+0x1ac/0x347 ? _raw_spin_unlock_irq+0x65/0x80 ? rest_init+0xf0/0xf0 kernel_init+0x1e/0x150 ret_from_fork+0x22/0x30 </TASK>

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Fix SCSI I/O completion and abort handler deadlock During stress I/O tests with 500+ vports, hard LOCKUP call traces are observed. CPU A: native_queued_spin_lock_slowpath+0x192 _raw_spin_lock_irqsave+0x32 lpfc_handle_fcp_err+0x4c6 lpfc_fcp_io_cmd_wqe_cmpl+0x964 lpfc_sli4_fp_handle_cqe+0x266 __lpfc_sli4_process_cq+0x105 __lpfc_sli4_hba_process_cq+0x3c lpfc_cq_poll_hdler+0x16 irq_poll_softirq+0x76 __softirqentry_text_start+0xe4 irq_exit+0xf7 do_IRQ+0x7f CPU B: native_queued_spin_lock_slowpath+0x5b _raw_spin_lock+0x1c lpfc_abort_handler+0x13e scmd_eh_abort_handler+0x85 process_one_work+0x1a7 worker_thread+0x30 kthread+0x112 ret_from_fork+0x1f Diagram of lockup: CPUA CPUB ---- ---- lpfc_cmd->buf_lock phba->hbalock lpfc_cmd->buf_lock phba->hbalock Fix by reordering the taking of the lpfc_cmd->buf_lock and phba->hbalock in lpfc_abort_handler routine so that it tries to take the lpfc_cmd->buf_lock first before phba->hbalock.

In the Linux kernel, the following vulnerability has been resolved: mptcp: init: protect sched with rcu_read_lock Enabling CONFIG_PROVE_RCU_LIST with its dependence CONFIG_RCU_EXPERT creates this splat when an MPTCP socket is created: ============================= WARNING: suspicious RCU usage 6.12.0-rc2+ #11 Not tainted ----------------------------- net/mptcp/sched.c:44 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 no locks held by mptcp_connect/176. stack backtrace: CPU: 0 UID: 0 PID: 176 Comm: mptcp_connect Not tainted 6.12.0-rc2+ #11 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:123) lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822) mptcp_sched_find (net/mptcp/sched.c:44 (discriminator 7)) mptcp_init_sock (net/mptcp/protocol.c:2867 (discriminator 1)) ? sock_init_data_uid (arch/x86/include/asm/atomic.h:28) inet_create.part.0.constprop.0 (net/ipv4/af_inet.c:386) ? __sock_create (include/linux/rcupdate.h:347 (discriminator 1)) __sock_create (net/socket.c:1576) __sys_socket (net/socket.c:1671) ? __pfx___sys_socket (net/socket.c:1712) ? do_user_addr_fault (arch/x86/mm/fault.c:1419 (discriminator 1)) __x64_sys_socket (net/socket.c:1728) do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) That's because when the socket is initialised, rcu_read_lock() is not used despite the explicit comment written above the declaration of mptcp_sched_find() in sched.c. Adding the missing lock/unlock avoids the warning.

In the Linux kernel, the following vulnerability has been resolved: tpm: Lock TPM chip in tpm_pm_suspend() first Setting TPM_CHIP_FLAG_SUSPENDED in the end of tpm_pm_suspend() can be racy according, as this leaves window for tpm_hwrng_read() to be called while the operation is in progress. The recent bug report gives also evidence of this behaviour. Aadress this by locking the TPM chip before checking any chip->flags both in tpm_pm_suspend() and tpm_hwrng_read(). Move TPM_CHIP_FLAG_SUSPENDED check inside tpm_get_random() so that it will be always checked only when the lock is reserved.

In the Linux kernel, the following vulnerability has been resolved: bcache: avoid journal no-space deadlock by reserving 1 journal bucket The journal no-space deadlock was reported time to time. Such deadlock can happen in the following situation. When all journal buckets are fully filled by active jset with heavy write I/O load, the cache set registration (after a reboot) will load all active jsets and inserting them into the btree again (which is called journal replay). If a journaled bkey is inserted into a btree node and results btree node split, new journal request might be triggered. For example, the btree grows one more level after the node split, then the root node record in cache device super block will be upgrade by bch_journal_meta() from bch_btree_set_root(). But there is no space in journal buckets, the journal replay has to wait for new journal bucket to be reclaimed after at least one journal bucket replayed. This is one example that how the journal no-space deadlock happens. The solution to avoid the deadlock is to reserve 1 journal bucket in run time, and only permit the reserved journal bucket to be used during cache set registration procedure for things like journal replay. Then the journal space will never be fully filled, there is no chance for journal no-space deadlock to happen anymore. This patch adds a new member "bool do_reserve" in struct journal, it is inititalized to 0 (false) when struct journal is allocated, and set to 1 (true) by bch_journal_space_reserve() when all initialization done in run_cache_set(). In the run time when journal_reclaim() tries to allocate a new journal bucket, free_journal_buckets() is called to check whether there are enough free journal buckets to use. If there is only 1 free journal bucket and journal->do_reserve is 1 (true), the last bucket is reserved and free_journal_buckets() will return 0 to indicate no free journal bucket. Then journal_reclaim() will give up, and try next time to see whetheer there is free journal bucket to allocate. By this method, there is always 1 jouranl bucket reserved in run time. During the cache set registration, journal->do_reserve is 0 (false), so the reserved journal bucket can be used to avoid the no-space deadlock.

In the Linux kernel, the following vulnerability has been resolved: loop: implement ->free_disk Ensure that the lo_device which is stored in the gendisk private data is valid until the gendisk is freed. Currently the loop driver uses a lot of effort to make sure a device is not freed when it is still in use, but to to fix a potential deadlock this will be relaxed a bit soon.

In the Linux kernel, the following vulnerability has been resolved: drm/vc4: Fix deadlock on DSI device attach error DSI device attach to DSI host will be done with host device's lock held. Un-registering host in "device attach" error path (ex: probe retry) will result in deadlock with below call trace and non operational DSI display. Startup Call trace: [ 35.043036] rt_mutex_slowlock.constprop.21+0x184/0x1b8 [ 35.043048] mutex_lock_nested+0x7c/0xc8 [ 35.043060] device_del+0x4c/0x3e8 [ 35.043075] device_unregister+0x20/0x40 [ 35.043082] mipi_dsi_remove_device_fn+0x18/0x28 [ 35.043093] device_for_each_child+0x68/0xb0 [ 35.043105] mipi_dsi_host_unregister+0x40/0x90 [ 35.043115] vc4_dsi_host_attach+0xf0/0x120 [vc4] [ 35.043199] mipi_dsi_attach+0x30/0x48 [ 35.043209] tc358762_probe+0x128/0x164 [tc358762] [ 35.043225] mipi_dsi_drv_probe+0x28/0x38 [ 35.043234] really_probe+0xc0/0x318 [ 35.043244] __driver_probe_device+0x80/0xe8 [ 35.043254] driver_probe_device+0xb8/0x118 [ 35.043263] __device_attach_driver+0x98/0xe8 [ 35.043273] bus_for_each_drv+0x84/0xd8 [ 35.043281] __device_attach+0xf0/0x150 [ 35.043290] device_initial_probe+0x1c/0x28 [ 35.043300] bus_probe_device+0xa4/0xb0 [ 35.043308] deferred_probe_work_func+0xa0/0xe0 [ 35.043318] process_one_work+0x254/0x700 [ 35.043330] worker_thread+0x4c/0x448 [ 35.043339] kthread+0x19c/0x1a8 [ 35.043348] ret_from_fork+0x10/0x20 Shutdown Call trace: [ 365.565417] Call trace: [ 365.565423] __switch_to+0x148/0x200 [ 365.565452] __schedule+0x340/0x9c8 [ 365.565467] schedule+0x48/0x110 [ 365.565479] schedule_timeout+0x3b0/0x448 [ 365.565496] wait_for_completion+0xac/0x138 [ 365.565509] __flush_work+0x218/0x4e0 [ 365.565523] flush_work+0x1c/0x28 [ 365.565536] wait_for_device_probe+0x68/0x158 [ 365.565550] device_shutdown+0x24/0x348 [ 365.565561] kernel_restart_prepare+0x40/0x50 [ 365.565578] kernel_restart+0x20/0x70 [ 365.565591] __do_sys_reboot+0x10c/0x220 [ 365.565605] __arm64_sys_reboot+0x2c/0x38 [ 365.565619] invoke_syscall+0x4c/0x110 [ 365.565634] el0_svc_common.constprop.3+0xfc/0x120 [ 365.565648] do_el0_svc+0x2c/0x90 [ 365.565661] el0_svc+0x4c/0xf0 [ 365.565671] el0t_64_sync_handler+0x90/0xb8 [ 365.565682] el0t_64_sync+0x180/0x184

In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid scanning potential huge holes When using devm_request_free_mem_region() and devm_memremap_pages() to add ZONE_DEVICE memory, if requested free mem region's end pfn were huge(e.g., 0x400000000), the node_end_pfn() will be also huge (see move_pfn_range_to_zone()). Thus it creates a huge hole between node_start_pfn() and node_end_pfn(). We found on some AMD APUs, amdkfd requested such a free mem region and created a huge hole. In such a case, following code snippet was just doing busy test_bit() looping on the huge hole. for (pfn = start_pfn; pfn < end_pfn; pfn++) { struct page *page = pfn_to_online_page(pfn); if (!page) continue; ... } So we got a soft lockup: watchdog: BUG: soft lockup - CPU#6 stuck for 26s! [bash:1221] CPU: 6 PID: 1221 Comm: bash Not tainted 5.15.0-custom #1 RIP: 0010:pfn_to_online_page+0x5/0xd0 Call Trace: ? kmemleak_scan+0x16a/0x440 kmemleak_write+0x306/0x3a0 ? common_file_perm+0x72/0x170 full_proxy_write+0x5c/0x90 vfs_write+0xb9/0x260 ksys_write+0x67/0xe0 __x64_sys_write+0x1a/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae I did some tests with the patch. (1) amdgpu module unloaded before the patch: real 0m0.976s user 0m0.000s sys 0m0.968s after the patch: real 0m0.981s user 0m0.000s sys 0m0.973s (2) amdgpu module loaded before the patch: real 0m35.365s user 0m0.000s sys 0m35.354s after the patch: real 0m1.049s user 0m0.000s sys 0m1.042s

In the Linux kernel, the following vulnerability has been resolved: net, neigh: Do not trigger immediate probes on NUD_FAILED from neigh_managed_work syzkaller was able to trigger a deadlock for NTF_MANAGED entries [0]: kworker/0:16/14617 is trying to acquire lock: ffffffff8d4dd370 (&tbl->lock){++-.}-{2:2}, at: ___neigh_create+0x9e1/0x2990 net/core/neighbour.c:652 [...] but task is already holding lock: ffffffff8d4dd370 (&tbl->lock){++-.}-{2:2}, at: neigh_managed_work+0x35/0x250 net/core/neighbour.c:1572 The neighbor entry turned to NUD_FAILED state, where __neigh_event_send() triggered an immediate probe as per commit cd28ca0a3dd1 ("neigh: reduce arp latency") via neigh_probe() given table lock was held. One option to fix this situation is to defer the neigh_probe() back to the neigh_timer_handler() similarly as pre cd28ca0a3dd1. For the case of NTF_MANAGED, this deferral is acceptable given this only happens on actual failure state and regular / expected state is NUD_VALID with the entry already present. The fix adds a parameter to __neigh_event_send() in order to communicate whether immediate probe is allowed or disallowed. Existing call-sites of neigh_event_send() default as-is to immediate probe. However, the neigh_managed_work() disables it via use of neigh_event_send_probe(). [0] <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2956 [inline] check_deadlock kernel/locking/lockdep.c:2999 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5027 lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline] _raw_write_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:334 ___neigh_create+0x9e1/0x2990 net/core/neighbour.c:652 ip6_finish_output2+0x1070/0x14f0 net/ipv6/ip6_output.c:123 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x61e/0xe90 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:451 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ndisc_send_skb+0xa99/0x17f0 net/ipv6/ndisc.c:508 ndisc_send_ns+0x3a9/0x840 net/ipv6/ndisc.c:650 ndisc_solicit+0x2cd/0x4f0 net/ipv6/ndisc.c:742 neigh_probe+0xc2/0x110 net/core/neighbour.c:1040 __neigh_event_send+0x37d/0x1570 net/core/neighbour.c:1201 neigh_event_send include/net/neighbour.h:470 [inline] neigh_managed_work+0x162/0x250 net/core/neighbour.c:1574 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307 worker_thread+0x657/0x1110 kernel/workqueue.c:2454 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK>

In the Linux kernel before 4.16.4, a double-locking error in drivers/usb/dwc3/gadget.c may potentially cause a deadlock with f_hid.

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix WARNING "do not call blocking ops when !TASK_RUNNING" wait_event_timeout() will set the state of the current task to TASK_UNINTERRUPTIBLE, before doing the condition check. This means that ksmbd_durable_scavenger_alive() will try to acquire the mutex while already in a sleeping state. The scheduler warns us by giving the following warning: do not call blocking ops when !TASK_RUNNING; state=2 set at [<0000000061515a6f>] prepare_to_wait_event+0x9f/0x6c0 WARNING: CPU: 2 PID: 4147 at kernel/sched/core.c:10099 __might_sleep+0x12f/0x160 mutex lock is not needed in ksmbd_durable_scavenger_alive().

In the Linux kernel, the following vulnerability has been resolved: USB: gadget: f_midi: f_midi_complete to call queue_work When using USB MIDI, a lock is attempted to be acquired twice through a re-entrant call to f_midi_transmit, causing a deadlock. Fix it by using queue_work() to schedule the inner f_midi_transmit() via a high priority work queue from the completion handler.

In the Linux kernel, the following vulnerability has been resolved: nvdimm: Fix firmware activation deadlock scenarios Lockdep reports the following deadlock scenarios for CXL root device power-management, device_prepare(), operations, and device_shutdown() operations for 'nd_region' devices: Chain exists of: &nvdimm_region_key --> &nvdimm_bus->reconfig_mutex --> system_transition_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(system_transition_mutex); lock(&nvdimm_bus->reconfig_mutex); lock(system_transition_mutex); lock(&nvdimm_region_key); Chain exists of: &cxl_nvdimm_bridge_key --> acpi_scan_lock --> &cxl_root_key Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&cxl_root_key); lock(acpi_scan_lock); lock(&cxl_root_key); lock(&cxl_nvdimm_bridge_key); These stem from holding nvdimm_bus_lock() over hibernate_quiet_exec() which walks the entire system device topology taking device_lock() along the way. The nvdimm_bus_lock() is protecting against unregistration, multiple simultaneous ops callers, and preventing activate_show() from racing activate_store(). For the first 2, the lock is redundant. Unregistration already flushes all ops users, and sysfs already prevents multiple threads to be active in an ops handler at the same time. For the last userspace should already be waiting for its last activate_store() to complete, and does not need activate_show() to flush the write side, so this lock usage can be deleted in these attributes.

In the Linux kernel, the following vulnerability has been resolved: ath11k: Fix frames flush failure caused by deadlock We are seeing below warnings: kernel: [25393.301506] ath11k_pci 0000:01:00.0: failed to flush mgmt transmit queue 0 kernel: [25398.421509] ath11k_pci 0000:01:00.0: failed to flush mgmt transmit queue 0 kernel: [25398.421831] ath11k_pci 0000:01:00.0: dropping mgmt frame for vdev 0, is_started 0 this means ath11k fails to flush mgmt. frames because wmi_mgmt_tx_work has no chance to run in 5 seconds. By setting /proc/sys/kernel/hung_task_timeout_secs to 20 and increasing ATH11K_FLUSH_TIMEOUT to 50 we get below warnings: kernel: [ 120.763160] INFO: task wpa_supplicant:924 blocked for more than 20 seconds. kernel: [ 120.763169] Not tainted 5.10.90 #12 kernel: [ 120.763177] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: [ 120.763186] task:wpa_supplicant state:D stack: 0 pid: 924 ppid: 1 flags:0x000043a0 kernel: [ 120.763201] Call Trace: kernel: [ 120.763214] __schedule+0x785/0x12fa kernel: [ 120.763224] ? lockdep_hardirqs_on_prepare+0xe2/0x1bb kernel: [ 120.763242] schedule+0x7e/0xa1 kernel: [ 120.763253] schedule_timeout+0x98/0xfe kernel: [ 120.763266] ? run_local_timers+0x4a/0x4a kernel: [ 120.763291] ath11k_mac_flush_tx_complete+0x197/0x2b1 [ath11k 13c3a9bf37790f4ac8103b3decf7ab4008ac314a] kernel: [ 120.763306] ? init_wait_entry+0x2e/0x2e kernel: [ 120.763343] __ieee80211_flush_queues+0x167/0x21f [mac80211 335da900954f1c5ea7f1613d92088ce83342042c] kernel: [ 120.763378] __ieee80211_recalc_idle+0x105/0x125 [mac80211 335da900954f1c5ea7f1613d92088ce83342042c] kernel: [ 120.763411] ieee80211_recalc_idle+0x14/0x27 [mac80211 335da900954f1c5ea7f1613d92088ce83342042c] kernel: [ 120.763441] ieee80211_free_chanctx+0x77/0xa2 [mac80211 335da900954f1c5ea7f1613d92088ce83342042c] kernel: [ 120.763473] __ieee80211_vif_release_channel+0x100/0x131 [mac80211 335da900954f1c5ea7f1613d92088ce83342042c] kernel: [ 120.763540] ieee80211_vif_release_channel+0x66/0x81 [mac80211 335da900954f1c5ea7f1613d92088ce83342042c] kernel: [ 120.763572] ieee80211_destroy_auth_data+0xa3/0xe6 [mac80211 335da900954f1c5ea7f1613d92088ce83342042c] kernel: [ 120.763612] ieee80211_mgd_deauth+0x178/0x29b [mac80211 335da900954f1c5ea7f1613d92088ce83342042c] kernel: [ 120.763654] cfg80211_mlme_deauth+0x1a8/0x22c [cfg80211 8945aa5bc2af5f6972336665d8ad6f9c191ad5be] kernel: [ 120.763697] nl80211_deauthenticate+0xfa/0x123 [cfg80211 8945aa5bc2af5f6972336665d8ad6f9c191ad5be] kernel: [ 120.763715] genl_rcv_msg+0x392/0x3c2 kernel: [ 120.763750] ? nl80211_associate+0x432/0x432 [cfg80211 8945aa5bc2af5f6972336665d8ad6f9c191ad5be] kernel: [ 120.763782] ? nl80211_associate+0x432/0x432 [cfg80211 8945aa5bc2af5f6972336665d8ad6f9c191ad5be] kernel: [ 120.763802] ? genl_rcv+0x36/0x36 kernel: [ 120.763814] netlink_rcv_skb+0x89/0xf7 kernel: [ 120.763829] genl_rcv+0x28/0x36 kernel: [ 120.763840] netlink_unicast+0x179/0x24b kernel: [ 120.763854] netlink_sendmsg+0x393/0x401 kernel: [ 120.763872] sock_sendmsg+0x72/0x76 kernel: [ 120.763886] ____sys_sendmsg+0x170/0x1e6 kernel: [ 120.763897] ? copy_msghdr_from_user+0x7a/0xa2 kernel: [ 120.763914] ___sys_sendmsg+0x95/0xd1 kernel: [ 120.763940] __sys_sendmsg+0x85/0xbf kernel: [ 120.763956] do_syscall_64+0x43/0x55 kernel: [ 120.763966] entry_SYSCALL_64_after_hwframe+0x44/0xa9 kernel: [ 120.763977] RIP: 0033:0x79089f3fcc83 kernel: [ 120.763986] RSP: 002b:00007ffe604f0508 EFLAGS: 00000246 ORIG_RAX: 000000000000002e kernel: [ 120.763997] RAX: ffffffffffffffda RBX: 000059b40e987690 RCX: 000079089f3fcc83 kernel: [ 120.764006] RDX: 0000000000000000 RSI: 00007ffe604f0558 RDI: 0000000000000009 kernel: [ 120.764014] RBP: 00007ffe604f0540 R08: 0000000000000004 R09: 0000000000400000 kernel: [ 120.764023] R10: 00007ffe604f0638 R11: 0000000000000246 R12: 000059b40ea04980 kernel: [ 120.764032] R13: 00007ffe604 ---truncated---

In the Linux kernel, the following vulnerability has been resolved: drivers: staging: rtl8723bs: Fix deadlock in rtw_surveydone_event_callback() There is a deadlock in rtw_surveydone_event_callback(), which is shown below: (Thread 1) | (Thread 2) | _set_timer() rtw_surveydone_event_callback()| mod_timer() spin_lock_bh() //(1) | (wait a time) ... | rtw_scan_timeout_handler() del_timer_sync() | spin_lock_bh() //(2) (wait timer to stop) | ... We hold pmlmepriv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need pmlmepriv->lock in position (2) of thread 2. As a result, rtw_surveydone_event_callback() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. What`s more, we change spin_lock_bh() in rtw_scan_timeout_handler() to spin_lock_irq(). Otherwise, spin_lock_bh() will also cause deadlock() in timer handler.

In the Linux kernel, the following vulnerability has been resolved: block: Fix potential deadlock in blk_ia_range_sysfs_show() When being read, a sysfs attribute is already protected against removal with the kobject node active reference counter. As a result, in blk_ia_range_sysfs_show(), there is no need to take the queue sysfs lock when reading the value of a range attribute. Using the queue sysfs lock in this function creates a potential deadlock situation with the disk removal, something that a lockdep signals with a splat when the device is removed: [ 760.703551] Possible unsafe locking scenario: [ 760.703551] [ 760.703554] CPU0 CPU1 [ 760.703556] ---- ---- [ 760.703558] lock(&q->sysfs_lock); [ 760.703565] lock(kn->active#385); [ 760.703573] lock(&q->sysfs_lock); [ 760.703579] lock(kn->active#385); [ 760.703587] [ 760.703587] *** DEADLOCK *** Solve this by removing the mutex_lock()/mutex_unlock() calls from blk_ia_range_sysfs_show().

The handle_stop_signal function in signal.c in Linux kernel 2.6.11 up to other versions before 2.6.13 and 2.6.12.6 allows local users to cause a denial of service (deadlock) by sending a SIGKILL to a real-time threaded process while it is performing a core dump.

In the Linux kernel, the following vulnerability has been resolved: RDMA/ib_srp: Fix a deadlock Remove the flush_workqueue(system_long_wq) call since flushing system_long_wq is deadlock-prone and since that call is redundant with a preceding cancel_work_sync()

In the Linux kernel, the following vulnerability has been resolved: VMCI: Use threaded irqs instead of tasklets The vmci_dispatch_dgs() tasklet function calls vmci_read_data() which uses wait_event() resulting in invalid sleep in an atomic context (and therefore potentially in a deadlock). Use threaded irqs to fix this issue and completely remove usage of tasklets. [ 20.264639] BUG: sleeping function called from invalid context at drivers/misc/vmw_vmci/vmci_guest.c:145 [ 20.264643] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 762, name: vmtoolsd [ 20.264645] preempt_count: 101, expected: 0 [ 20.264646] RCU nest depth: 0, expected: 0 [ 20.264647] 1 lock held by vmtoolsd/762: [ 20.264648] #0: ffff0000874ae440 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: vsock_connect+0x60/0x330 [vsock] [ 20.264658] Preemption disabled at: [ 20.264659] [<ffff80000151d7d8>] vmci_send_datagram+0x44/0xa0 [vmw_vmci] [ 20.264665] CPU: 0 PID: 762 Comm: vmtoolsd Not tainted 5.19.0-0.rc8.20220727git39c3c396f813.60.fc37.aarch64 #1 [ 20.264667] Hardware name: VMware, Inc. VBSA/VBSA, BIOS VEFI 12/31/2020 [ 20.264668] Call trace: [ 20.264669] dump_backtrace+0xc4/0x130 [ 20.264672] show_stack+0x24/0x80 [ 20.264673] dump_stack_lvl+0x88/0xb4 [ 20.264676] dump_stack+0x18/0x34 [ 20.264677] __might_resched+0x1a0/0x280 [ 20.264679] __might_sleep+0x58/0x90 [ 20.264681] vmci_read_data+0x74/0x120 [vmw_vmci] [ 20.264683] vmci_dispatch_dgs+0x64/0x204 [vmw_vmci] [ 20.264686] tasklet_action_common.constprop.0+0x13c/0x150 [ 20.264688] tasklet_action+0x40/0x50 [ 20.264689] __do_softirq+0x23c/0x6b4 [ 20.264690] __irq_exit_rcu+0x104/0x214 [ 20.264691] irq_exit_rcu+0x1c/0x50 [ 20.264693] el1_interrupt+0x38/0x6c [ 20.264695] el1h_64_irq_handler+0x18/0x24 [ 20.264696] el1h_64_irq+0x68/0x6c [ 20.264697] preempt_count_sub+0xa4/0xe0 [ 20.264698] _raw_spin_unlock_irqrestore+0x64/0xb0 [ 20.264701] vmci_send_datagram+0x7c/0xa0 [vmw_vmci] [ 20.264703] vmci_datagram_dispatch+0x84/0x100 [vmw_vmci] [ 20.264706] vmci_datagram_send+0x2c/0x40 [vmw_vmci] [ 20.264709] vmci_transport_send_control_pkt+0xb8/0x120 [vmw_vsock_vmci_transport] [ 20.264711] vmci_transport_connect+0x40/0x7c [vmw_vsock_vmci_transport] [ 20.264713] vsock_connect+0x278/0x330 [vsock] [ 20.264715] __sys_connect_file+0x8c/0xc0 [ 20.264718] __sys_connect+0x84/0xb4 [ 20.264720] __arm64_sys_connect+0x2c/0x3c [ 20.264721] invoke_syscall+0x78/0x100 [ 20.264723] el0_svc_common.constprop.0+0x68/0x124 [ 20.264724] do_el0_svc+0x38/0x4c [ 20.264725] el0_svc+0x60/0x180 [ 20.264726] el0t_64_sync_handler+0x11c/0x150 [ 20.264728] el0t_64_sync+0x190/0x194

In the Linux kernel, the following vulnerability has been resolved: f2fs: initialize locks earlier in f2fs_fill_super() syzbot is reporting lockdep warning at f2fs_handle_error() [1], for spin_lock(&sbi->error_lock) is called before spin_lock_init() is called. For safe locking in error handling, move initialization of locks (and obvious structures) in f2fs_fill_super() to immediately after memory allocation.

In the Linux kernel, the following vulnerability has been resolved: pds_core: Fix pdsc_check_pci_health function to use work thread When the driver notices fw_status == 0xff it tries to perform a PCI reset on itself via pci_reset_function() in the context of the driver's health thread. However, pdsc_reset_prepare calls pdsc_stop_health_thread(), which attempts to stop/flush the health thread. This results in a deadlock because the stop/flush will never complete since the driver called pci_reset_function() from the health thread context. Fix by changing the pdsc_check_pci_health_function() to queue a newly introduced pdsc_pci_reset_thread() on the pdsc's work queue. Unloading the driver in the fw_down/dead state uncovered another issue, which can be seen in the following trace: WARNING: CPU: 51 PID: 6914 at kernel/workqueue.c:1450 __queue_work+0x358/0x440 [...] RIP: 0010:__queue_work+0x358/0x440 [...] Call Trace: <TASK> ? __warn+0x85/0x140 ? __queue_work+0x358/0x440 ? report_bug+0xfc/0x1e0 ? handle_bug+0x3f/0x70 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? __queue_work+0x358/0x440 queue_work_on+0x28/0x30 pdsc_devcmd_locked+0x96/0xe0 [pds_core] pdsc_devcmd_reset+0x71/0xb0 [pds_core] pdsc_teardown+0x51/0xe0 [pds_core] pdsc_remove+0x106/0x200 [pds_core] pci_device_remove+0x37/0xc0 device_release_driver_internal+0xae/0x140 driver_detach+0x48/0x90 bus_remove_driver+0x6d/0xf0 pci_unregister_driver+0x2e/0xa0 pdsc_cleanup_module+0x10/0x780 [pds_core] __x64_sys_delete_module+0x142/0x2b0 ? syscall_trace_enter.isra.18+0x126/0x1a0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7fbd9d03a14b [...] Fix this by preventing the devcmd reset if the FW is not running.

In the Linux kernel, the following vulnerability has been resolved: driver core: fix deadlock in __device_attach In __device_attach function, The lock holding logic is as follows: ... __device_attach device_lock(dev) // get lock dev async_schedule_dev(__device_attach_async_helper, dev); // func async_schedule_node async_schedule_node_domain(func) entry = kzalloc(sizeof(struct async_entry), GFP_ATOMIC); /* when fail or work limit, sync to execute func, but __device_attach_async_helper will get lock dev as well, which will lead to A-A deadlock. */ if (!entry || atomic_read(&entry_count) > MAX_WORK) { func; else queue_work_node(node, system_unbound_wq, &entry->work) device_unlock(dev) As shown above, when it is allowed to do async probes, because of out of memory or work limit, async work is not allowed, to do sync execute instead. it will lead to A-A deadlock because of __device_attach_async_helper getting lock dev. To fix the deadlock, move the async_schedule_dev outside device_lock, as we can see, in async_schedule_node_domain, the parameter of queue_work_node is system_unbound_wq, so it can accept concurrent operations. which will also not change the code logic, and will not lead to deadlock.

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix deadlock between concurrent dio writes when low on free data space When reserving data space for a direct IO write we can end up deadlocking if we have multiple tasks attempting a write to the same file range, there are multiple extents covered by that file range, we are low on available space for data and the writes don't expand the inode's i_size. The deadlock can happen like this: 1) We have a file with an i_size of 1M, at offset 0 it has an extent with a size of 128K and at offset 128K it has another extent also with a size of 128K; 2) Task A does a direct IO write against file range [0, 256K), and because the write is within the i_size boundary, it takes the inode's lock (VFS level) in shared mode; 3) Task A locks the file range [0, 256K) at btrfs_dio_iomap_begin(), and then gets the extent map for the extent covering the range [0, 128K). At btrfs_get_blocks_direct_write(), it creates an ordered extent for that file range ([0, 128K)); 4) Before returning from btrfs_dio_iomap_begin(), it unlocks the file range [0, 256K); 5) Task A executes btrfs_dio_iomap_begin() again, this time for the file range [128K, 256K), and locks the file range [128K, 256K); 6) Task B starts a direct IO write against file range [0, 256K) as well. It also locks the inode in shared mode, as it's within the i_size limit, and then tries to lock file range [0, 256K). It is able to lock the subrange [0, 128K) but then blocks waiting for the range [128K, 256K), as it is currently locked by task A; 7) Task A enters btrfs_get_blocks_direct_write() and tries to reserve data space. Because we are low on available free space, it triggers the async data reclaim task, and waits for it to reserve data space; 8) The async reclaim task decides to wait for all existing ordered extents to complete (through btrfs_wait_ordered_roots()). It finds the ordered extent previously created by task A for the file range [0, 128K) and waits for it to complete; 9) The ordered extent for the file range [0, 128K) can not complete because it blocks at btrfs_finish_ordered_io() when trying to lock the file range [0, 128K). This results in a deadlock, because: - task B is holding the file range [0, 128K) locked, waiting for the range [128K, 256K) to be unlocked by task A; - task A is holding the file range [128K, 256K) locked and it's waiting for the async data reclaim task to satisfy its space reservation request; - the async data reclaim task is waiting for ordered extent [0, 128K) to complete, but the ordered extent can not complete because the file range [0, 128K) is currently locked by task B, which is waiting on task A to unlock file range [128K, 256K) and task A waiting on the async data reclaim task. This results in a deadlock between 4 task: task A, task B, the async data reclaim task and the task doing ordered extent completion (a work queue task). This type of deadlock can sporadically be triggered by the test case generic/300 from fstests, and results in a stack trace like the following: [12084.033689] INFO: task kworker/u16:7:123749 blocked for more than 241 seconds. [12084.034877] Not tainted 5.18.0-rc2-btrfs-next-115 #1 [12084.035562] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [12084.036548] task:kworker/u16:7 state:D stack: 0 pid:123749 ppid: 2 flags:0x00004000 [12084.036554] Workqueue: btrfs-flush_delalloc btrfs_work_helper [btrfs] [12084.036599] Call Trace: [12084.036601] <TASK> [12084.036606] __schedule+0x3cb/0xed0 [12084.036616] schedule+0x4e/0xb0 [12084.036620] btrfs_start_ordered_extent+0x109/0x1c0 [btrfs] [12084.036651] ? prepare_to_wait_exclusive+0xc0/0xc0 [12084.036659] btrfs_run_ordered_extent_work+0x1a/0x30 [btrfs] [12084.036688] btrfs_work_helper+0xf8/0x400 [btrfs] [12084.0367 ---truncated---

In the Linux kernel, the following vulnerability has been resolved: drivers: staging: rtl8192e: Fix deadlock in rtllib_beacons_stop() There is a deadlock in rtllib_beacons_stop(), which is shown below: (Thread 1) | (Thread 2) | rtllib_send_beacon() rtllib_beacons_stop() | mod_timer() spin_lock_irqsave() //(1) | (wait a time) ... | rtllib_send_beacon_cb() del_timer_sync() | spin_lock_irqsave() //(2) (wait timer to stop) | ... We hold ieee->beacon_lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need ieee->beacon_lock in position (2) of thread 2. As a result, rtllib_beacons_stop() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_irqsave(), which could let timer handler to obtain the needed lock.

In the Linux kernel, the following vulnerability has been resolved: drivers: staging: rtl8192bs: Fix deadlock in rtw_joinbss_event_prehandle() There is a deadlock in rtw_joinbss_event_prehandle(), which is shown below: (Thread 1) | (Thread 2) | _set_timer() rtw_joinbss_event_prehandle()| mod_timer() spin_lock_bh() //(1) | (wait a time) ... | _rtw_join_timeout_handler() del_timer_sync() | spin_lock_bh() //(2) (wait timer to stop) | ... We hold pmlmepriv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need pmlmepriv->lock in position (2) of thread 2. As a result, rtw_joinbss_event_prehandle() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. What`s more, we change spin_lock_bh() to spin_lock_irq() in _rtw_join_timeout_handler() in order to prevent deadlock.

In the Linux kernel, the following vulnerability has been resolved: drivers: tty: serial: Fix deadlock in sa1100_set_termios() There is a deadlock in sa1100_set_termios(), which is shown below: (Thread 1) | (Thread 2) | sa1100_enable_ms() sa1100_set_termios() | mod_timer() spin_lock_irqsave() //(1) | (wait a time) ... | sa1100_timeout() del_timer_sync() | spin_lock_irqsave() //(2) (wait timer to stop) | ... We hold sport->port.lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need sport->port.lock in position (2) of thread 2. As a result, sa1100_set_termios() will block forever. This patch moves del_timer_sync() before spin_lock_irqsave() in order to prevent the deadlock.

In the Linux kernel, the following vulnerability has been resolved: scsi: ufs: core: Fix deadlock during RTC update There is a deadlock when runtime suspend waits for the flush of RTC work, and the RTC work calls ufshcd_rpm_get_sync() to wait for runtime resume. Here is deadlock backtrace: kworker/0:1 D 4892.876354 10 10971 4859 0x4208060 0x8 10 0 120 670730152367 ptr f0ffff80c2e40000 0 1 0x00000001 0x000000ff 0x000000ff 0x000000ff <ffffffee5e71ddb0> __switch_to+0x1a8/0x2d4 <ffffffee5e71e604> __schedule+0x684/0xa98 <ffffffee5e71ea60> schedule+0x48/0xc8 <ffffffee5e725f78> schedule_timeout+0x48/0x170 <ffffffee5e71fb74> do_wait_for_common+0x108/0x1b0 <ffffffee5e71efe0> wait_for_completion+0x44/0x60 <ffffffee5d6de968> __flush_work+0x39c/0x424 <ffffffee5d6decc0> __cancel_work_sync+0xd8/0x208 <ffffffee5d6dee2c> cancel_delayed_work_sync+0x14/0x28 <ffffffee5e2551b8> __ufshcd_wl_suspend+0x19c/0x480 <ffffffee5e255fb8> ufshcd_wl_runtime_suspend+0x3c/0x1d4 <ffffffee5dffd80c> scsi_runtime_suspend+0x78/0xc8 <ffffffee5df93580> __rpm_callback+0x94/0x3e0 <ffffffee5df90b0c> rpm_suspend+0x2d4/0x65c <ffffffee5df91448> __pm_runtime_suspend+0x80/0x114 <ffffffee5dffd95c> scsi_runtime_idle+0x38/0x6c <ffffffee5df912f4> rpm_idle+0x264/0x338 <ffffffee5df90f14> __pm_runtime_idle+0x80/0x110 <ffffffee5e24ce44> ufshcd_rtc_work+0x128/0x1e4 <ffffffee5d6e3a40> process_one_work+0x26c/0x650 <ffffffee5d6e65c8> worker_thread+0x260/0x3d8 <ffffffee5d6edec8> kthread+0x110/0x134 <ffffffee5d616b18> ret_from_fork+0x10/0x20 Skip updating RTC if RPM state is not RPM_ACTIVE.

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Move cfg_log_verbose check before calling lpfc_dmp_dbg() In an attempt to log message 0126 with LOG_TRACE_EVENT, the following hard lockup call trace hangs the system. Call Trace: _raw_spin_lock_irqsave+0x32/0x40 lpfc_dmp_dbg.part.32+0x28/0x220 [lpfc] lpfc_cmpl_els_fdisc+0x145/0x460 [lpfc] lpfc_sli_cancel_jobs+0x92/0xd0 [lpfc] lpfc_els_flush_cmd+0x43c/0x670 [lpfc] lpfc_els_flush_all_cmd+0x37/0x60 [lpfc] lpfc_sli4_async_event_proc+0x956/0x1720 [lpfc] lpfc_do_work+0x1485/0x1d70 [lpfc] kthread+0x112/0x130 ret_from_fork+0x1f/0x40 Kernel panic - not syncing: Hard LOCKUP The same CPU tries to claim the phba->port_list_lock twice. Move the cfg_log_verbose checks as part of the lpfc_printf_vlog() and lpfc_printf_log() macros before calling lpfc_dmp_dbg(). There is no need to take the phba->port_list_lock within lpfc_dmp_dbg().

In the Linux kernel, the following vulnerability has been resolved: btrfs: get rid of warning on transaction commit when using flushoncommit When using the flushoncommit mount option, during almost every transaction commit we trigger a warning from __writeback_inodes_sb_nr(): $ cat fs/fs-writeback.c: (...) static void __writeback_inodes_sb_nr(struct super_block *sb, ... { (...) WARN_ON(!rwsem_is_locked(&sb->s_umount)); (...) } (...) The trace produced in dmesg looks like the following: [947.473890] WARNING: CPU: 5 PID: 930 at fs/fs-writeback.c:2610 __writeback_inodes_sb_nr+0x7e/0xb3 [947.481623] Modules linked in: nfsd nls_cp437 cifs asn1_decoder cifs_arc4 fscache cifs_md4 ipmi_ssif [947.489571] CPU: 5 PID: 930 Comm: btrfs-transacti Not tainted 95.16.3-srb-asrock-00001-g36437ad63879 #186 [947.497969] RIP: 0010:__writeback_inodes_sb_nr+0x7e/0xb3 [947.502097] Code: 24 10 4c 89 44 24 18 c6 (...) [947.519760] RSP: 0018:ffffc90000777e10 EFLAGS: 00010246 [947.523818] RAX: 0000000000000000 RBX: 0000000000963300 RCX: 0000000000000000 [947.529765] RDX: 0000000000000000 RSI: 000000000000fa51 RDI: ffffc90000777e50 [947.535740] RBP: ffff888101628a90 R08: ffff888100955800 R09: ffff888100956000 [947.541701] R10: 0000000000000002 R11: 0000000000000001 R12: ffff888100963488 [947.547645] R13: ffff888100963000 R14: ffff888112fb7200 R15: ffff888100963460 [947.553621] FS: 0000000000000000(0000) GS:ffff88841fd40000(0000) knlGS:0000000000000000 [947.560537] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [947.565122] CR2: 0000000008be50c4 CR3: 000000000220c000 CR4: 00000000001006e0 [947.571072] Call Trace: [947.572354] <TASK> [947.573266] btrfs_commit_transaction+0x1f1/0x998 [947.576785] ? start_transaction+0x3ab/0x44e [947.579867] ? schedule_timeout+0x8a/0xdd [947.582716] transaction_kthread+0xe9/0x156 [947.585721] ? btrfs_cleanup_transaction.isra.0+0x407/0x407 [947.590104] kthread+0x131/0x139 [947.592168] ? set_kthread_struct+0x32/0x32 [947.595174] ret_from_fork+0x22/0x30 [947.597561] </TASK> [947.598553] ---[ end trace 644721052755541c ]--- This is because we started using writeback_inodes_sb() to flush delalloc when committing a transaction (when using -o flushoncommit), in order to avoid deadlocks with filesystem freeze operations. This change was made by commit ce8ea7cc6eb313 ("btrfs: don't call btrfs_start_delalloc_roots in flushoncommit"). After that change we started producing that warning, and every now and then a user reports this since the warning happens too often, it spams dmesg/syslog, and a user is unsure if this reflects any problem that might compromise the filesystem's reliability. We can not just lock the sb->s_umount semaphore before calling writeback_inodes_sb(), because that would at least deadlock with filesystem freezing, since at fs/super.c:freeze_super() sync_filesystem() is called while we are holding that semaphore in write mode, and that can trigger a transaction commit, resulting in a deadlock. It would also trigger the same type of deadlock in the unmount path. Possibly, it could also introduce some other locking dependencies that lockdep would report. To fix this call try_to_writeback_inodes_sb() instead of writeback_inodes_sb(), because that will try to read lock sb->s_umount and then will only call writeback_inodes_sb() if it was able to lock it. This is fine because the cases where it can't read lock sb->s_umount are during a filesystem unmount or during a filesystem freeze - in those cases sb->s_umount is write locked and sync_filesystem() is called, which calls writeback_inodes_sb(). In other words, in all cases where we can't take a read lock on sb->s_umount, writeback is already being triggered elsewhere. An alternative would be to call btrfs_start_delalloc_roots() with a number of pages different from LONG_MAX, for example matching the number of delalloc bytes we currently have, in ---truncated---

In the Linux kernel, the following vulnerability has been resolved: drivers: staging: rtl8192eu: Fix deadlock in rtw_joinbss_event_prehandle There is a deadlock in rtw_joinbss_event_prehandle(), which is shown below: (Thread 1) | (Thread 2) | _set_timer() rtw_joinbss_event_prehandle()| mod_timer() spin_lock_bh() //(1) | (wait a time) ... | rtw_join_timeout_handler() | _rtw_join_timeout_handler() del_timer_sync() | spin_lock_bh() //(2) (wait timer to stop) | ... We hold pmlmepriv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need pmlmepriv->lock in position (2) of thread 2. As a result, rtw_joinbss_event_prehandle() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. What`s more, we change spin_lock_bh() to spin_lock_irq() in _rtw_join_timeout_handler() in order to prevent deadlock.

In the Linux kernel, the following vulnerability has been resolved: cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all() syzbot is hitting percpu_rwsem_assert_held(&cpu_hotplug_lock) warning at cpuset_attach() [1], for commit 4f7e7236435ca0ab ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") missed that cpuset_attach() is also called from cgroup_attach_task_all(). Add cpus_read_lock() like what cgroup_procs_write_start() does.

In the Linux kernel, the following vulnerability has been resolved: nfs_common: must not hold RCU while calling nfsd_file_put_local Move holding the RCU from nfs_to_nfsd_file_put_local to nfs_to_nfsd_net_put. It is the call to nfs_to->nfsd_serv_put that requires the RCU anyway (the puts for nfsd_file and netns were combined to avoid an extra indirect reference but that micro-optimization isn't possible now). This fixes xfstests generic/013 and it triggering: "Voluntary context switch within RCU read-side critical section!" [ 143.545738] Call Trace: [ 143.546206] <TASK> [ 143.546625] ? show_regs+0x6d/0x80 [ 143.547267] ? __warn+0x91/0x140 [ 143.547951] ? rcu_note_context_switch+0x496/0x5d0 [ 143.548856] ? report_bug+0x193/0x1a0 [ 143.549557] ? handle_bug+0x63/0xa0 [ 143.550214] ? exc_invalid_op+0x1d/0x80 [ 143.550938] ? asm_exc_invalid_op+0x1f/0x30 [ 143.551736] ? rcu_note_context_switch+0x496/0x5d0 [ 143.552634] ? wakeup_preempt+0x62/0x70 [ 143.553358] __schedule+0xaa/0x1380 [ 143.554025] ? _raw_spin_unlock_irqrestore+0x12/0x40 [ 143.554958] ? try_to_wake_up+0x1fe/0x6b0 [ 143.555715] ? wake_up_process+0x19/0x20 [ 143.556452] schedule+0x2e/0x120 [ 143.557066] schedule_preempt_disabled+0x19/0x30 [ 143.557933] rwsem_down_read_slowpath+0x24d/0x4a0 [ 143.558818] ? xfs_efi_item_format+0x50/0xc0 [xfs] [ 143.559894] down_read+0x4e/0xb0 [ 143.560519] xlog_cil_commit+0x1b2/0xbc0 [xfs] [ 143.561460] ? _raw_spin_unlock+0x12/0x30 [ 143.562212] ? xfs_inode_item_precommit+0xc7/0x220 [xfs] [ 143.563309] ? xfs_trans_run_precommits+0x69/0xd0 [xfs] [ 143.564394] __xfs_trans_commit+0xb5/0x330 [xfs] [ 143.565367] xfs_trans_roll+0x48/0xc0 [xfs] [ 143.566262] xfs_defer_trans_roll+0x57/0x100 [xfs] [ 143.567278] xfs_defer_finish_noroll+0x27a/0x490 [xfs] [ 143.568342] xfs_defer_finish+0x1a/0x80 [xfs] [ 143.569267] xfs_bunmapi_range+0x4d/0xb0 [xfs] [ 143.570208] xfs_itruncate_extents_flags+0x13d/0x230 [xfs] [ 143.571353] xfs_free_eofblocks+0x12e/0x190 [xfs] [ 143.572359] xfs_file_release+0x12d/0x140 [xfs] [ 143.573324] __fput+0xe8/0x2d0 [ 143.573922] __fput_sync+0x1d/0x30 [ 143.574574] nfsd_filp_close+0x33/0x60 [nfsd] [ 143.575430] nfsd_file_free+0x96/0x150 [nfsd] [ 143.576274] nfsd_file_put+0xf7/0x1a0 [nfsd] [ 143.577104] nfsd_file_put_local+0x18/0x30 [nfsd] [ 143.578070] nfs_close_local_fh+0x101/0x110 [nfs_localio] [ 143.579079] __put_nfs_open_context+0xc9/0x180 [nfs] [ 143.580031] nfs_file_clear_open_context+0x4a/0x60 [nfs] [ 143.581038] nfs_file_release+0x3e/0x60 [nfs] [ 143.581879] __fput+0xe8/0x2d0 [ 143.582464] __fput_sync+0x1d/0x30 [ 143.583108] __x64_sys_close+0x41/0x80 [ 143.583823] x64_sys_call+0x189a/0x20d0 [ 143.584552] do_syscall_64+0x64/0x170 [ 143.585240] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 143.586185] RIP: 0033:0x7f3c5153efd7

Guests can trigger deadlock in Linux netback driver T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] The patch for XSA-392 introduced another issue which might result in a deadlock when trying to free the SKB of a packet dropped due to the XSA-392 handling (CVE-2022-42328). Additionally when dropping packages for other reasons the same deadlock could occur in case of netpoll being active for the interface the xen-netback driver is connected to (CVE-2022-42329).

In the Linux kernel, the following vulnerability has been resolved: drivers: usb: host: Fix deadlock in oxu_bus_suspend() There is a deadlock in oxu_bus_suspend(), which is shown below: (Thread 1) | (Thread 2) | timer_action() oxu_bus_suspend() | mod_timer() spin_lock_irq() //(1) | (wait a time) ... | oxu_watchdog() del_timer_sync() | spin_lock_irq() //(2) (wait timer to stop) | ... We hold oxu->lock in position (1) of thread 1, and use del_timer_sync() to wait timer to stop, but timer handler also need oxu->lock in position (2) of thread 2. As a result, oxu_bus_suspend() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_irq(), which could let timer handler to obtain the needed lock.

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: MGMT: Fix possible deadlocks This fixes possible deadlocks like the following caused by hci_cmd_sync_dequeue causing the destroy function to run: INFO: task kworker/u19:0:143 blocked for more than 120 seconds. Tainted: G W O 6.8.0-2024-03-19-intel-next-iLS-24ww14 #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u19:0 state:D stack:0 pid:143 tgid:143 ppid:2 flags:0x00004000 Workqueue: hci0 hci_cmd_sync_work [bluetooth] Call Trace: <TASK> __schedule+0x374/0xaf0 schedule+0x3c/0xf0 schedule_preempt_disabled+0x1c/0x30 __mutex_lock.constprop.0+0x3ef/0x7a0 __mutex_lock_slowpath+0x13/0x20 mutex_lock+0x3c/0x50 mgmt_set_connectable_complete+0xa4/0x150 [bluetooth] ? kfree+0x211/0x2a0 hci_cmd_sync_dequeue+0xae/0x130 [bluetooth] ? __pfx_cmd_complete_rsp+0x10/0x10 [bluetooth] cmd_complete_rsp+0x26/0x80 [bluetooth] mgmt_pending_foreach+0x4d/0x70 [bluetooth] __mgmt_power_off+0x8d/0x180 [bluetooth] ? _raw_spin_unlock_irq+0x23/0x40 hci_dev_close_sync+0x445/0x5b0 [bluetooth] hci_set_powered_sync+0x149/0x250 [bluetooth] set_powered_sync+0x24/0x60 [bluetooth] hci_cmd_sync_work+0x90/0x150 [bluetooth] process_one_work+0x13e/0x300 worker_thread+0x2f7/0x420 ? __pfx_worker_thread+0x10/0x10 kthread+0x107/0x140 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x3d/0x60 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK>

Guests can trigger deadlock in Linux netback driver T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] The patch for XSA-392 introduced another issue which might result in a deadlock when trying to free the SKB of a packet dropped due to the XSA-392 handling (CVE-2022-42328). Additionally when dropping packages for other reasons the same deadlock could occur in case of netpoll being active for the interface the xen-netback driver is connected to (CVE-2022-42329).

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid potential deadlock in f2fs_record_stop_reason() syzbot reports deadlock issue of f2fs as below: ====================================================== WARNING: possible circular locking dependency detected 6.12.0-rc3-syzkaller-00087-gc964ced77262 #0 Not tainted ------------------------------------------------------ kswapd0/79 is trying to acquire lock: ffff888011824088 (&sbi->sb_lock){++++}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2199 [inline] ffff888011824088 (&sbi->sb_lock){++++}-{3:3}, at: f2fs_record_stop_reason+0x52/0x1d0 fs/f2fs/super.c:4068 but task is already holding lock: ffff88804bd92610 (sb_internal#2){.+.+}-{0:0}, at: f2fs_evict_inode+0x662/0x15c0 fs/f2fs/inode.c:842 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (sb_internal#2){.+.+}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1716 [inline] sb_start_intwrite+0x4d/0x1c0 include/linux/fs.h:1899 f2fs_evict_inode+0x662/0x15c0 fs/f2fs/inode.c:842 evict+0x4e8/0x9b0 fs/inode.c:725 f2fs_evict_inode+0x1a4/0x15c0 fs/f2fs/inode.c:807 evict+0x4e8/0x9b0 fs/inode.c:725 dispose_list fs/inode.c:774 [inline] prune_icache_sb+0x239/0x2f0 fs/inode.c:963 super_cache_scan+0x38c/0x4b0 fs/super.c:223 do_shrink_slab+0x701/0x1160 mm/shrinker.c:435 shrink_slab+0x1093/0x14d0 mm/shrinker.c:662 shrink_one+0x43b/0x850 mm/vmscan.c:4818 shrink_many mm/vmscan.c:4879 [inline] lru_gen_shrink_node mm/vmscan.c:4957 [inline] shrink_node+0x3799/0x3de0 mm/vmscan.c:5937 kswapd_shrink_node mm/vmscan.c:6765 [inline] balance_pgdat mm/vmscan.c:6957 [inline] kswapd+0x1ca3/0x3700 mm/vmscan.c:7226 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:3834 [inline] fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3848 might_alloc include/linux/sched/mm.h:318 [inline] prepare_alloc_pages+0x147/0x5b0 mm/page_alloc.c:4493 __alloc_pages_noprof+0x16f/0x710 mm/page_alloc.c:4722 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265 alloc_pages_noprof mm/mempolicy.c:2345 [inline] folio_alloc_noprof+0x128/0x180 mm/mempolicy.c:2352 filemap_alloc_folio_noprof+0xdf/0x500 mm/filemap.c:1010 do_read_cache_folio+0x2eb/0x850 mm/filemap.c:3787 read_mapping_folio include/linux/pagemap.h:1011 [inline] f2fs_commit_super+0x3c0/0x7d0 fs/f2fs/super.c:4032 f2fs_record_stop_reason+0x13b/0x1d0 fs/f2fs/super.c:4079 f2fs_handle_critical_error+0x2ac/0x5c0 fs/f2fs/super.c:4174 f2fs_write_inode+0x35f/0x4d0 fs/f2fs/inode.c:785 write_inode fs/fs-writeback.c:1503 [inline] __writeback_single_inode+0x711/0x10d0 fs/fs-writeback.c:1723 writeback_single_inode+0x1f3/0x660 fs/fs-writeback.c:1779 sync_inode_metadata+0xc4/0x120 fs/fs-writeback.c:2849 f2fs_release_file+0xa8/0x100 fs/f2fs/file.c:1941 __fput+0x23f/0x880 fs/file_table.c:431 task_work_run+0x24f/0x310 kernel/task_work.c:228 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f ---truncated---

A flaw was found in the Linux kernel's Layer 2 Tunneling Protocol (L2TP). A missing lock when clearing sk_user_data can lead to a race condition and NULL pointer dereference. A local user could use this flaw to potentially crash the system causing a denial of service.

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix hang in nilfs_lookup_dirty_data_buffers() Syzbot reported a hang issue in migrate_pages_batch() called by mbind() and nilfs_lookup_dirty_data_buffers() called in the log writer of nilfs2. While migrate_pages_batch() locks a folio and waits for the writeback to complete, the log writer thread that should bring the writeback to completion picks up the folio being written back in nilfs_lookup_dirty_data_buffers() that it calls for subsequent log creation and was trying to lock the folio. Thus causing a deadlock. In the first place, it is unexpected that folios/pages in the middle of writeback will be updated and become dirty. Nilfs2 adds a checksum to verify the validity of the log being written and uses it for recovery at mount, so data changes during writeback are suppressed. Since this is broken, an unclean shutdown could potentially cause recovery to fail. Investigation revealed that the root cause is that the wait for writeback completion in nilfs_page_mkwrite() is conditional, and if the backing device does not require stable writes, data may be modified without waiting. Fix these issues by making nilfs_page_mkwrite() wait for writeback to finish regardless of the stable write requirement of the backing device.

In the Linux kernel, the following vulnerability has been resolved: mptcp: fix possible deadlock in subflow diag Syzbot and Eric reported a lockdep splat in the subflow diag: WARNING: possible circular locking dependency detected 6.8.0-rc4-syzkaller-00212-g40b9385dd8e6 #0 Not tainted syz-executor.2/24141 is trying to acquire lock: ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline] ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137 but task is already holding lock: ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: inet_diag_dump_icsk+0x39f/0x1f80 net/ipv4/inet_diag.c:1038 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&h->lhash2[i].lock){+.+.}-{2:2}: lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __inet_hash+0x335/0xbe0 net/ipv4/inet_hashtables.c:743 inet_csk_listen_start+0x23a/0x320 net/ipv4/inet_connection_sock.c:1261 __inet_listen_sk+0x2a2/0x770 net/ipv4/af_inet.c:217 inet_listen+0xa3/0x110 net/ipv4/af_inet.c:239 rds_tcp_listen_init+0x3fd/0x5a0 net/rds/tcp_listen.c:316 rds_tcp_init_net+0x141/0x320 net/rds/tcp.c:577 ops_init+0x352/0x610 net/core/net_namespace.c:136 __register_pernet_operations net/core/net_namespace.c:1214 [inline] register_pernet_operations+0x2cb/0x660 net/core/net_namespace.c:1283 register_pernet_device+0x33/0x80 net/core/net_namespace.c:1370 rds_tcp_init+0x62/0xd0 net/rds/tcp.c:735 do_one_initcall+0x238/0x830 init/main.c:1236 do_initcall_level+0x157/0x210 init/main.c:1298 do_initcalls+0x3f/0x80 init/main.c:1314 kernel_init_freeable+0x42f/0x5d0 init/main.c:1551 kernel_init+0x1d/0x2a0 init/main.c:1441 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242 -> #0 (k-sk_lock-AF_INET6){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 lock_sock_fast include/net/sock.h:1723 [inline] subflow_get_info+0x166/0xd20 net/mptcp/diag.c:28 tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline] tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137 inet_sk_diag_fill+0x10ed/0x1e00 net/ipv4/inet_diag.c:345 inet_diag_dump_icsk+0x55b/0x1f80 net/ipv4/inet_diag.c:1061 __inet_diag_dump+0x211/0x3a0 net/ipv4/inet_diag.c:1263 inet_diag_dump_compat+0x1c1/0x2d0 net/ipv4/inet_diag.c:1371 netlink_dump+0x59b/0xc80 net/netlink/af_netlink.c:2264 __netlink_dump_start+0x5df/0x790 net/netlink/af_netlink.c:2370 netlink_dump_start include/linux/netlink.h:338 [inline] inet_diag_rcv_msg_compat+0x209/0x4c0 net/ipv4/inet_diag.c:1405 sock_diag_rcv_msg+0xe7/0x410 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2543 sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:280 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline] netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1367 netlink_sendmsg+0xa3b/0xd70 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 As noted by Eric we can break the lock dependency chain avoid dumping ---truncated---

In the Linux kernel, the following vulnerability has been resolved: net: implement lockless setsockopt(SO_PEEK_OFF) syzbot reported a lockdep violation [1] involving af_unix support of SO_PEEK_OFF. Since SO_PEEK_OFF is inherently not thread safe (it uses a per-socket sk_peek_off field), there is really no point to enforce a pointless thread safety in the kernel. After this patch : - setsockopt(SO_PEEK_OFF) no longer acquires the socket lock. - skb_consume_udp() no longer has to acquire the socket lock. - af_unix no longer needs a special version of sk_set_peek_off(), because it does not lock u->iolock anymore. As a followup, we could replace prot->set_peek_off to be a boolean and avoid an indirect call, since we always use sk_set_peek_off(). [1] WARNING: possible circular locking dependency detected 6.8.0-rc4-syzkaller-00267-g0f1dd5e91e2b #0 Not tainted syz-executor.2/30025 is trying to acquire lock: ffff8880765e7d80 (&u->iolock){+.+.}-{3:3}, at: unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789 but task is already holding lock: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline] ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1060 [inline] ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sk_setsockopt+0xe52/0x3360 net/core/sock.c:1193 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sk_lock-AF_UNIX){+.+.}-{0:0}: lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 lock_sock_nested+0x48/0x100 net/core/sock.c:3524 lock_sock include/net/sock.h:1691 [inline] __unix_dgram_recvmsg+0x1275/0x12c0 net/unix/af_unix.c:2415 sock_recvmsg_nosec+0x18e/0x1d0 net/socket.c:1046 ____sys_recvmsg+0x3c0/0x470 net/socket.c:2801 ___sys_recvmsg net/socket.c:2845 [inline] do_recvmmsg+0x474/0xae0 net/socket.c:2939 __sys_recvmmsg net/socket.c:3018 [inline] __do_sys_recvmmsg net/socket.c:3041 [inline] __se_sys_recvmmsg net/socket.c:3034 [inline] __x64_sys_recvmmsg+0x199/0x250 net/socket.c:3034 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 -> #0 (&u->iolock){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789 sk_setsockopt+0x207e/0x3360 do_sock_setsockopt+0x2fb/0x720 net/socket.c:2307 __sys_setsockopt+0x1ad/0x250 net/socket.c:2334 __do_sys_setsockopt net/socket.c:2343 [inline] __se_sys_setsockopt net/socket.c:2340 [inline] __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sk_lock-AF_UNIX); lock(&u->iolock); lock(sk_lock-AF_UNIX); lock(&u->iolock); *** DEADLOCK *** 1 lock held by syz-executor.2/30025: #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline] #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1060 [inline] #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sk_setsockopt+0xe52/0x3360 net/core/sock.c:1193 stack backtrace: CPU: 0 PID: 30025 Comm: syz-executor.2 Not tainted 6.8.0-rc4-syzkaller-00267-g0f1dd5e91e2b #0 Hardware name: Google Google C ---truncated---

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_mirred: use the backlog for mirred ingress The test Davide added in commit ca22da2fbd69 ("act_mirred: use the backlog for nested calls to mirred ingress") hangs our testing VMs every 10 or so runs, with the familiar tcp_v4_rcv -> tcp_v4_rcv deadlock reported by lockdep. The problem as previously described by Davide (see Link) is that if we reverse flow of traffic with the redirect (egress -> ingress) we may reach the same socket which generated the packet. And we may still be holding its socket lock. The common solution to such deadlocks is to put the packet in the Rx backlog, rather than run the Rx path inline. Do that for all egress -> ingress reversals, not just once we started to nest mirred calls. In the past there was a concern that the backlog indirection will lead to loss of error reporting / less accurate stats. But the current workaround does not seem to address the issue.

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Prevent deadlock while disabling aRFS When disabling aRFS under the `priv->state_lock`, any scheduled aRFS works are canceled using the `cancel_work_sync` function, which waits for the work to end if it has already started. However, while waiting for the work handler, the handler will try to acquire the `state_lock` which is already acquired. The worker acquires the lock to delete the rules if the state is down, which is not the worker's responsibility since disabling aRFS deletes the rules. Add an aRFS state variable, which indicates whether the aRFS is enabled and prevent adding rules when the aRFS is disabled. Kernel log: ====================================================== WARNING: possible circular locking dependency detected 6.7.0-rc4_net_next_mlx5_5483eb2 #1 Tainted: G I ------------------------------------------------------ ethtool/386089 is trying to acquire lock: ffff88810f21ce68 ((work_completion)(&rule->arfs_work)){+.+.}-{0:0}, at: __flush_work+0x74/0x4e0 but task is already holding lock: ffff8884a1808cc0 (&priv->state_lock){+.+.}-{3:3}, at: mlx5e_ethtool_set_channels+0x53/0x200 [mlx5_core] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&priv->state_lock){+.+.}-{3:3}: __mutex_lock+0x80/0xc90 arfs_handle_work+0x4b/0x3b0 [mlx5_core] process_one_work+0x1dc/0x4a0 worker_thread+0x1bf/0x3c0 kthread+0xd7/0x100 ret_from_fork+0x2d/0x50 ret_from_fork_asm+0x11/0x20 -> #0 ((work_completion)(&rule->arfs_work)){+.+.}-{0:0}: __lock_acquire+0x17b4/0x2c80 lock_acquire+0xd0/0x2b0 __flush_work+0x7a/0x4e0 __cancel_work_timer+0x131/0x1c0 arfs_del_rules+0x143/0x1e0 [mlx5_core] mlx5e_arfs_disable+0x1b/0x30 [mlx5_core] mlx5e_ethtool_set_channels+0xcb/0x200 [mlx5_core] ethnl_set_channels+0x28f/0x3b0 ethnl_default_set_doit+0xec/0x240 genl_family_rcv_msg_doit+0xd0/0x120 genl_rcv_msg+0x188/0x2c0 netlink_rcv_skb+0x54/0x100 genl_rcv+0x24/0x40 netlink_unicast+0x1a1/0x270 netlink_sendmsg+0x214/0x460 __sock_sendmsg+0x38/0x60 __sys_sendto+0x113/0x170 __x64_sys_sendto+0x20/0x30 do_syscall_64+0x40/0xe0 entry_SYSCALL_64_after_hwframe+0x46/0x4e other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&priv->state_lock); lock((work_completion)(&rule->arfs_work)); lock(&priv->state_lock); lock((work_completion)(&rule->arfs_work)); *** DEADLOCK *** 3 locks held by ethtool/386089: #0: ffffffff82ea7210 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 #1: ffffffff82e94c88 (rtnl_mutex){+.+.}-{3:3}, at: ethnl_default_set_doit+0xd3/0x240 #2: ffff8884a1808cc0 (&priv->state_lock){+.+.}-{3:3}, at: mlx5e_ethtool_set_channels+0x53/0x200 [mlx5_core] stack backtrace: CPU: 15 PID: 386089 Comm: ethtool Tainted: G I 6.7.0-rc4_net_next_mlx5_5483eb2 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x60/0xa0 check_noncircular+0x144/0x160 __lock_acquire+0x17b4/0x2c80 lock_acquire+0xd0/0x2b0 ? __flush_work+0x74/0x4e0 ? save_trace+0x3e/0x360 ? __flush_work+0x74/0x4e0 __flush_work+0x7a/0x4e0 ? __flush_work+0x74/0x4e0 ? __lock_acquire+0xa78/0x2c80 ? lock_acquire+0xd0/0x2b0 ? mark_held_locks+0x49/0x70 __cancel_work_timer+0x131/0x1c0 ? mark_held_locks+0x49/0x70 arfs_del_rules+0x143/0x1e0 [mlx5_core] mlx5e_arfs_disable+0x1b/0x30 [mlx5_core] mlx5e_ethtool_set_channels+0xcb/0x200 [mlx5_core] ethnl_set_channels+0x28f/0x3b0 ethnl_default_set_doit+0xec/0x240 genl_family_rcv_msg_doit+0xd0/0x120 genl_rcv_msg+0x188/0x2c0 ? ethn ---truncated---