In the Linux kernel, the following vulnerability has been resolved: scsi: ufs: core: Fix another deadlock during RTC update If ufshcd_rtc_work calls ufshcd_rpm_put_sync() and the pm's usage_count is 0, we will enter the runtime suspend callback. However, the runtime suspend callback will wait to flush ufshcd_rtc_work, causing a deadlock. Replace ufshcd_rpm_put_sync() with ufshcd_rpm_put() to avoid the deadlock.

In the Linux kernel, the following vulnerability has been resolved: scsi: megaraid_sas: Fix for a potential deadlock This fixes a 'possible circular locking dependency detected' warning CPU0 CPU1 ---- ---- lock(&instance->reset_mutex); lock(&shost->scan_mutex); lock(&instance->reset_mutex); lock(&shost->scan_mutex); Fix this by temporarily releasing the reset_mutex.

In the Linux kernel, the following vulnerability has been resolved: virtio-blk: don't keep queue frozen during system suspend Commit 4ce6e2db00de ("virtio-blk: Ensure no requests in virtqueues before deleting vqs.") replaces queue quiesce with queue freeze in virtio-blk's PM callbacks. And the motivation is to drain inflight IOs before suspending. block layer's queue freeze looks very handy, but it is also easy to cause deadlock, such as, any attempt to call into bio_queue_enter() may run into deadlock if the queue is frozen in current context. There are all kinds of ->suspend() called in suspend context, so keeping queue frozen in the whole suspend context isn't one good idea. And Marek reported lockdep warning[1] caused by virtio-blk's freeze queue in virtblk_freeze(). [1] https://lore.kernel.org/linux-block/ca16370e-d646-4eee-b9cc-87277c89c43c@samsung.com/ Given the motivation is to drain in-flight IOs, it can be done by calling freeze & unfreeze, meantime restore to previous behavior by keeping queue quiesced during suspend.

In the Linux kernel, the following vulnerability has been resolved: media: uvcvideo: Fix deadlock during uvc_probe If uvc_probe() fails, it can end up calling uvc_status_unregister() before uvc_status_init() is called. Fix this by checking if dev->status is NULL or not in uvc_status_unregister().

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

In the Linux kernel, the following vulnerability has been resolved: block: Prevent potential deadlocks in zone write plug error recovery Zone write plugging for handling writes to zones of a zoned block device always execute a zone report whenever a write BIO to a zone fails. The intent of this is to ensure that the tracking of a zone write pointer is always correct to ensure that the alignment to a zone write pointer of write BIOs can be checked on submission and that we can always correctly emulate zone append operations using regular write BIOs. However, this error recovery scheme introduces a potential deadlock if a device queue freeze is initiated while BIOs are still plugged in a zone write plug and one of these write operation fails. In such case, the disk zone write plug error recovery work is scheduled and executes a report zone. This in turn can result in a request allocation in the underlying driver to issue the report zones command to the device. But with the device queue freeze already started, this allocation will block, preventing the report zone execution and the continuation of the processing of the plugged BIOs. As plugged BIOs hold a queue usage reference, the queue freeze itself will never complete, resulting in a deadlock. Avoid this problem by completely removing from the zone write plugging code the use of report zones operations after a failed write operation, instead relying on the device user to either execute a report zones, reset the zone, finish the zone, or give up writing to the device (which is a fairly common pattern for file systems which degrade to read-only after write failures). This is not an unreasonnable requirement as all well-behaved applications, FSes and device mapper already use report zones to recover from write errors whenever possible by comparing the current position of a zone write pointer with what their assumption about the position is. The changes to remove the automatic error recovery are as follows: - Completely remove the error recovery work and its associated resources (zone write plug list head, disk error list, and disk zone_wplugs_work work struct). This also removes the functions disk_zone_wplug_set_error() and disk_zone_wplug_clear_error(). - Change the BLK_ZONE_WPLUG_ERROR zone write plug flag into BLK_ZONE_WPLUG_NEED_WP_UPDATE. This new flag is set for a zone write plug whenever a write opration targetting the zone of the zone write plug fails. This flag indicates that the zone write pointer offset is not reliable and that it must be updated when the next report zone, reset zone, finish zone or disk revalidation is executed. - Modify blk_zone_write_plug_bio_endio() to set the BLK_ZONE_WPLUG_NEED_WP_UPDATE flag for the target zone of a failed write BIO. - Modify the function disk_zone_wplug_set_wp_offset() to clear this new flag, thus implementing recovery of a correct write pointer offset with the reset (all) zone and finish zone operations. - Modify blkdev_report_zones() to always use the disk_report_zones_cb() callback so that disk_zone_wplug_sync_wp_offset() can be called for any zone marked with the BLK_ZONE_WPLUG_NEED_WP_UPDATE flag. This implements recovery of a correct write pointer offset for zone write plugs marked with BLK_ZONE_WPLUG_NEED_WP_UPDATE and within the range of the report zones operation executed by the user. - Modify blk_revalidate_seq_zone() to call disk_zone_wplug_sync_wp_offset() for all sequential write required zones when a zoned block device is revalidated, thus always resolving any inconsistency between the write pointer offset of zone write plugs and the actual write pointer position of sequential zones.

In the Linux kernel, the following vulnerability has been resolved: posix-clock: posix-clock: Fix unbalanced locking in pc_clock_settime() If get_clock_desc() succeeds, it calls fget() for the clockid's fd, and get the clk->rwsem read lock, so the error path should release the lock to make the lock balance and fput the clockid's fd to make the refcount balance and release the fd related resource. However the below commit left the error path locked behind resulting in unbalanced locking. Check timespec64_valid_strict() before get_clock_desc() to fix it, because the "ts" is not changed after that. [pabeni@redhat.com: fixed commit message typo]

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential deadlock with newly created symlinks Syzbot reported that page_symlink(), called by nilfs_symlink(), triggers memory reclamation involving the filesystem layer, which can result in circular lock dependencies among the reader/writer semaphore nilfs->ns_segctor_sem, s_writers percpu_rwsem (intwrite) and the fs_reclaim pseudo lock. This is because after commit 21fc61c73c39 ("don't put symlink bodies in pagecache into highmem"), the gfp flags of the page cache for symbolic links are overwritten to GFP_KERNEL via inode_nohighmem(). This is not a problem for symlinks read from the backing device, because the __GFP_FS flag is dropped after inode_nohighmem() is called. However, when a new symlink is created with nilfs_symlink(), the gfp flags remain overwritten to GFP_KERNEL. Then, memory allocation called from page_symlink() etc. triggers memory reclamation including the FS layer, which may call nilfs_evict_inode() or nilfs_dirty_inode(). And these can cause a deadlock if they are called while nilfs->ns_segctor_sem is held: Fix this issue by dropping the __GFP_FS flag from the page cache GFP flags of newly created symlinks in the same way that nilfs_new_inode() and __nilfs_read_inode() do, as a workaround until we adopt nofs allocation scope consistently or improve the locking constraints.

In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Fix reader locking when changing the sub buffer order The function ring_buffer_subbuf_order_set() updates each ring_buffer_per_cpu and installs new sub buffers that match the requested page order. This operation may be invoked concurrently with readers that rely on some of the modified data, such as the head bit (RB_PAGE_HEAD), or the ring_buffer_per_cpu.pages and reader_page pointers. However, no exclusive access is acquired by ring_buffer_subbuf_order_set(). Modifying the mentioned data while a reader also operates on them can then result in incorrect memory access and various crashes. Fix the problem by taking the reader_lock when updating a specific ring_buffer_per_cpu in ring_buffer_subbuf_order_set().

In the Linux kernel, the following vulnerability has been resolved: ocfs2: remove unreasonable unlock in ocfs2_read_blocks Patch series "Misc fixes for ocfs2_read_blocks", v5. This series contains 2 fixes for ocfs2_read_blocks(). The first patch fix the issue reported by syzbot, which detects bad unlock balance in ocfs2_read_blocks(). The second patch fixes an issue reported by Heming Zhao when reviewing above fix. This patch (of 2): There was a lock release before exiting, so remove the unreasonable unlock.

In the Linux kernel, the following vulnerability has been resolved: drm/xe/guc_submit: add missing locking in wedged_fini Any non-wedged queue can have a zero refcount here and can be running concurrently with an async queue destroy, therefore dereferencing the queue ptr to check wedge status after the lookup can trigger UAF if queue is not wedged. Fix this by keeping the submission_state lock held around the check to postpone the free and make the check safe, before dropping again around the put() to avoid the deadlock. (cherry picked from commit d28af0b6b9580b9f90c265a7da0315b0ad20bbfd)

In the Linux kernel, the following vulnerability has been resolved: i2c: stm32f7: Do not prepare/unprepare clock during runtime suspend/resume In case there is any sort of clock controller attached to this I2C bus controller, for example Versaclock or even an AIC32x4 I2C codec, then an I2C transfer triggered from the clock controller clk_ops .prepare callback may trigger a deadlock on drivers/clk/clk.c prepare_lock mutex. This is because the clock controller first grabs the prepare_lock mutex and then performs the prepare operation, including its I2C access. The I2C access resumes this I2C bus controller via .runtime_resume callback, which calls clk_prepare_enable(), which attempts to grab the prepare_lock mutex again and deadlocks. Since the clock are already prepared since probe() and unprepared in remove(), use simple clk_enable()/clk_disable() calls to enable and disable the clock on runtime suspend and resume, to avoid hitting the prepare_lock mutex.

In the Linux kernel, the following vulnerability has been resolved: btrfs: don't take dev_replace rwsem on task already holding it Running fstests btrfs/011 with MKFS_OPTIONS="-O rst" to force the usage of the RAID stripe-tree, we get the following splat from lockdep: BTRFS info (device sdd): dev_replace from /dev/sdd (devid 1) to /dev/sdb started ============================================ WARNING: possible recursive locking detected 6.11.0-rc3-btrfs-for-next #599 Not tainted -------------------------------------------- btrfs/2326 is trying to acquire lock: ffff88810f215c98 (&fs_info->dev_replace.rwsem){++++}-{3:3}, at: btrfs_map_block+0x39f/0x2250 but task is already holding lock: ffff88810f215c98 (&fs_info->dev_replace.rwsem){++++}-{3:3}, at: btrfs_map_block+0x39f/0x2250 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&fs_info->dev_replace.rwsem); lock(&fs_info->dev_replace.rwsem); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by btrfs/2326: #0: ffff88810f215c98 (&fs_info->dev_replace.rwsem){++++}-{3:3}, at: btrfs_map_block+0x39f/0x2250 stack backtrace: CPU: 1 UID: 0 PID: 2326 Comm: btrfs Not tainted 6.11.0-rc3-btrfs-for-next #599 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: <TASK> dump_stack_lvl+0x5b/0x80 __lock_acquire+0x2798/0x69d0 ? __pfx___lock_acquire+0x10/0x10 ? __pfx___lock_acquire+0x10/0x10 lock_acquire+0x19d/0x4a0 ? btrfs_map_block+0x39f/0x2250 ? __pfx_lock_acquire+0x10/0x10 ? find_held_lock+0x2d/0x110 ? lock_is_held_type+0x8f/0x100 down_read+0x8e/0x440 ? btrfs_map_block+0x39f/0x2250 ? __pfx_down_read+0x10/0x10 ? do_raw_read_unlock+0x44/0x70 ? _raw_read_unlock+0x23/0x40 btrfs_map_block+0x39f/0x2250 ? btrfs_dev_replace_by_ioctl+0xd69/0x1d00 ? btrfs_bio_counter_inc_blocked+0xd9/0x2e0 ? __kasan_slab_alloc+0x6e/0x70 ? __pfx_btrfs_map_block+0x10/0x10 ? __pfx_btrfs_bio_counter_inc_blocked+0x10/0x10 ? kmem_cache_alloc_noprof+0x1f2/0x300 ? mempool_alloc_noprof+0xed/0x2b0 btrfs_submit_chunk+0x28d/0x17e0 ? __pfx_btrfs_submit_chunk+0x10/0x10 ? bvec_alloc+0xd7/0x1b0 ? bio_add_folio+0x171/0x270 ? __pfx_bio_add_folio+0x10/0x10 ? __kasan_check_read+0x20/0x20 btrfs_submit_bio+0x37/0x80 read_extent_buffer_pages+0x3df/0x6c0 btrfs_read_extent_buffer+0x13e/0x5f0 read_tree_block+0x81/0xe0 read_block_for_search+0x4bd/0x7a0 ? __pfx_read_block_for_search+0x10/0x10 btrfs_search_slot+0x78d/0x2720 ? __pfx_btrfs_search_slot+0x10/0x10 ? lock_is_held_type+0x8f/0x100 ? kasan_save_track+0x14/0x30 ? __kasan_slab_alloc+0x6e/0x70 ? kmem_cache_alloc_noprof+0x1f2/0x300 btrfs_get_raid_extent_offset+0x181/0x820 ? __pfx_lock_acquire+0x10/0x10 ? __pfx_btrfs_get_raid_extent_offset+0x10/0x10 ? down_read+0x194/0x440 ? __pfx_down_read+0x10/0x10 ? do_raw_read_unlock+0x44/0x70 ? _raw_read_unlock+0x23/0x40 btrfs_map_block+0x5b5/0x2250 ? __pfx_btrfs_map_block+0x10/0x10 scrub_submit_initial_read+0x8fe/0x11b0 ? __pfx_scrub_submit_initial_read+0x10/0x10 submit_initial_group_read+0x161/0x3a0 ? lock_release+0x20e/0x710 ? __pfx_submit_initial_group_read+0x10/0x10 ? __pfx_lock_release+0x10/0x10 scrub_simple_mirror.isra.0+0x3eb/0x580 scrub_stripe+0xe4d/0x1440 ? lock_release+0x20e/0x710 ? __pfx_scrub_stripe+0x10/0x10 ? __pfx_lock_release+0x10/0x10 ? do_raw_read_unlock+0x44/0x70 ? _raw_read_unlock+0x23/0x40 scrub_chunk+0x257/0x4a0 scrub_enumerate_chunks+0x64c/0xf70 ? __mutex_unlock_slowpath+0x147/0x5f0 ? __pfx_scrub_enumerate_chunks+0x10/0x10 ? bit_wait_timeout+0xb0/0x170 ? __up_read+0x189/0x700 ? scrub_workers_get+0x231/0x300 ? up_write+0x490/0x4f0 btrfs_scrub_dev+0x52e/0xcd0 ? create_pending_snapshots+0x230/0x250 ? __pfx_btrfs_scrub_dev+0x10/0x10 btrfs_dev_replace_by_ioctl+0xd69/0x1d00 ? lock_acquire+0x19d/0x4a0 ? __pfx_btrfs_dev_replace_by_ioctl+0x10/0x10 ? ---truncated---

In the Linux kernel, the following vulnerability has been resolved: dma-debug: fix a possible deadlock on radix_lock radix_lock() shouldn't be held while holding dma_hash_entry[idx].lock otherwise, there's a possible deadlock scenario when dma debug API is called holding rq_lock(): CPU0 CPU1 CPU2 dma_free_attrs() check_unmap() add_dma_entry() __schedule() //out (A) rq_lock() get_hash_bucket() (A) dma_entry_hash check_sync() (A) radix_lock() (W) dma_entry_hash dma_entry_free() (W) radix_lock() // CPU2's one (W) rq_lock() CPU1 situation can happen when it extending radix tree and it tries to wake up kswapd via wake_all_kswapd(). CPU2 situation can happen while perf_event_task_sched_out() (i.e. dma sync operation is called while deleting perf_event using etm and etr tmc which are Arm Coresight hwtracing driver backends). To remove this possible situation, call dma_entry_free() after put_hash_bucket() in check_unmap().

In the Linux kernel, the following vulnerability has been resolved: firmware: qcom: uefisecapp: Fix deadlock in qcuefi_acquire() If the __qcuefi pointer is not set, then in the original code, we would hold onto the lock. That means that if we tried to set it later, then it would cause a deadlock. Drop the lock on the error path. That's what all the callers are expecting.

In the Linux kernel, the following vulnerability has been resolved: i2c: tegra: Do not mark ACPI devices as irq safe On ACPI machines, the tegra i2c module encounters an issue due to a mutex being called inside a spinlock. This leads to the following bug: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:585 ... Call trace: __might_sleep __mutex_lock_common mutex_lock_nested acpi_subsys_runtime_resume rpm_resume tegra_i2c_xfer The problem arises because during __pm_runtime_resume(), the spinlock &dev->power.lock is acquired before rpm_resume() is called. Later, rpm_resume() invokes acpi_subsys_runtime_resume(), which relies on mutexes, triggering the error. To address this issue, devices on ACPI are now marked as not IRQ-safe, considering the dependency of acpi_subsys_runtime_resume() on mutexes.

The ptrace_start function in kernel/ptrace.c in the Linux kernel 2.6.18 does not properly handle simultaneous execution of the do_coredump function, which allows local users to cause a denial of service (deadlock) via vectors involving the ptrace system call and a coredumping thread.

In the Linux kernel, the following vulnerability has been resolved: RDMA/hns: Fix soft lockup under heavy CEQE load CEQEs are handled in interrupt handler currently. This may cause the CPU core staying in interrupt context too long and lead to soft lockup under heavy load. Handle CEQEs in BH workqueue and set an upper limit for the number of CEQE handled by a single call of work handler.

In the Linux kernel, the following vulnerability has been resolved: i2c: pnx: Fix potential deadlock warning from del_timer_sync() call in isr When del_timer_sync() is called in an interrupt context it throws a warning because of potential deadlock. The timer is used only to exit from wait_for_completion() after a timeout so replacing the call with wait_for_completion_timeout() allows to remove the problematic timer and its related functions altogether.

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Fix missing lock on sync reset reload On sync reset reload work, when remote host updates devlink on reload actions performed on that host, it misses taking devlink lock before calling devlink_remote_reload_actions_performed() which results in triggering lock assert like the following: WARNING: CPU: 4 PID: 1164 at net/devlink/core.c:261 devl_assert_locked+0x3e/0x50 … CPU: 4 PID: 1164 Comm: kworker/u96:6 Tainted: G S W 6.10.0-rc2+ #116 Hardware name: Supermicro SYS-2028TP-DECTR/X10DRT-PT, BIOS 2.0 12/18/2015 Workqueue: mlx5_fw_reset_events mlx5_sync_reset_reload_work [mlx5_core] RIP: 0010:devl_assert_locked+0x3e/0x50 … Call Trace: <TASK> ? __warn+0xa4/0x210 ? devl_assert_locked+0x3e/0x50 ? report_bug+0x160/0x280 ? handle_bug+0x3f/0x80 ? exc_invalid_op+0x17/0x40 ? asm_exc_invalid_op+0x1a/0x20 ? devl_assert_locked+0x3e/0x50 devlink_notify+0x88/0x2b0 ? mlx5_attach_device+0x20c/0x230 [mlx5_core] ? __pfx_devlink_notify+0x10/0x10 ? process_one_work+0x4b6/0xbb0 process_one_work+0x4b6/0xbb0 […]

In the Linux kernel, the following vulnerability has been resolved: riscv: kexec: Avoid deadlock in kexec crash path If the kexec crash code is called in the interrupt context, the machine_kexec_mask_interrupts() function will trigger a deadlock while trying to acquire the irqdesc spinlock and then deactivate irqchip in irq_set_irqchip_state() function. Unlike arm64, riscv only requires irq_eoi handler to complete EOI and keeping irq_set_irqchip_state() will only leave this possible deadlock without any use. So we simply remove it.

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7921s: fix potential hung tasks during chip recovery During chip recovery (e.g. chip reset), there is a possible situation that kernel worker reset_work is holding the lock and waiting for kernel thread stat_worker to be parked, while stat_worker is waiting for the release of the same lock. It causes a deadlock resulting in the dumping of hung tasks messages and possible rebooting of the device. This patch prevents the execution of stat_worker during the chip recovery.

In the Linux kernel, the following vulnerability has been resolved: drop_monitor: replace spin_lock by raw_spin_lock trace_drop_common() is called with preemption disabled, and it acquires a spin_lock. This is problematic for RT kernels because spin_locks are sleeping locks in this configuration, which causes the following splat: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 449, name: rcuc/47 preempt_count: 1, expected: 0 RCU nest depth: 2, expected: 2 5 locks held by rcuc/47/449: #0: ff1100086ec30a60 ((softirq_ctrl.lock)){+.+.}-{2:2}, at: __local_bh_disable_ip+0x105/0x210 #1: ffffffffb394a280 (rcu_read_lock){....}-{1:2}, at: rt_spin_lock+0xbf/0x130 #2: ffffffffb394a280 (rcu_read_lock){....}-{1:2}, at: __local_bh_disable_ip+0x11c/0x210 #3: ffffffffb394a160 (rcu_callback){....}-{0:0}, at: rcu_do_batch+0x360/0xc70 #4: ff1100086ee07520 (&data->lock){+.+.}-{2:2}, at: trace_drop_common.constprop.0+0xb5/0x290 irq event stamp: 139909 hardirqs last enabled at (139908): [<ffffffffb1df2b33>] _raw_spin_unlock_irqrestore+0x63/0x80 hardirqs last disabled at (139909): [<ffffffffb19bd03d>] trace_drop_common.constprop.0+0x26d/0x290 softirqs last enabled at (139892): [<ffffffffb07a1083>] __local_bh_enable_ip+0x103/0x170 softirqs last disabled at (139898): [<ffffffffb0909b33>] rcu_cpu_kthread+0x93/0x1f0 Preemption disabled at: [<ffffffffb1de786b>] rt_mutex_slowunlock+0xab/0x2e0 CPU: 47 PID: 449 Comm: rcuc/47 Not tainted 6.9.0-rc2-rt1+ #7 Hardware name: Dell Inc. PowerEdge R650/0Y2G81, BIOS 1.6.5 04/15/2022 Call Trace: <TASK> dump_stack_lvl+0x8c/0xd0 dump_stack+0x14/0x20 __might_resched+0x21e/0x2f0 rt_spin_lock+0x5e/0x130 ? trace_drop_common.constprop.0+0xb5/0x290 ? skb_queue_purge_reason.part.0+0x1bf/0x230 trace_drop_common.constprop.0+0xb5/0x290 ? preempt_count_sub+0x1c/0xd0 ? _raw_spin_unlock_irqrestore+0x4a/0x80 ? __pfx_trace_drop_common.constprop.0+0x10/0x10 ? rt_mutex_slowunlock+0x26a/0x2e0 ? skb_queue_purge_reason.part.0+0x1bf/0x230 ? __pfx_rt_mutex_slowunlock+0x10/0x10 ? skb_queue_purge_reason.part.0+0x1bf/0x230 trace_kfree_skb_hit+0x15/0x20 trace_kfree_skb+0xe9/0x150 kfree_skb_reason+0x7b/0x110 skb_queue_purge_reason.part.0+0x1bf/0x230 ? __pfx_skb_queue_purge_reason.part.0+0x10/0x10 ? mark_lock.part.0+0x8a/0x520 ... trace_drop_common() also disables interrupts, but this is a minor issue because we could easily replace it with a local_lock. Replace the spin_lock with raw_spin_lock to avoid sleeping in atomic context.

In the Linux kernel, the following vulnerability has been resolved: pinctrl: fix deadlock in create_pinctrl() when handling -EPROBE_DEFER In create_pinctrl(), pinctrl_maps_mutex is acquired before calling add_setting(). If add_setting() returns -EPROBE_DEFER, create_pinctrl() calls pinctrl_free(). However, pinctrl_free() attempts to acquire pinctrl_maps_mutex, which is already held by create_pinctrl(), leading to a potential deadlock. This patch resolves the issue by releasing pinctrl_maps_mutex before calling pinctrl_free(), preventing the deadlock. This bug was discovered and resolved using Coverity Static Analysis Security Testing (SAST) by Synopsys, Inc.

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: cancel all works upon hci_unregister_dev() syzbot is reporting that calling hci_release_dev() from hci_error_reset() due to hci_dev_put() from hci_error_reset() can cause deadlock at destroy_workqueue(), for hci_error_reset() is called from hdev->req_workqueue which destroy_workqueue() needs to flush. We need to make sure that hdev->{rx_work,cmd_work,tx_work} which are queued into hdev->workqueue and hdev->{power_on,error_reset} which are queued into hdev->req_workqueue are no longer running by the moment destroy_workqueue(hdev->workqueue); destroy_workqueue(hdev->req_workqueue); are called from hci_release_dev(). Call cancel_work_sync() on these work items from hci_unregister_dev() as soon as hdev->list is removed from hci_dev_list.

In the Linux kernel, the following vulnerability has been resolved: f2fs: don't set RO when shutting down f2fs Shutdown does not check the error of thaw_super due to readonly, which causes a deadlock like below. f2fs_ioc_shutdown(F2FS_GOING_DOWN_FULLSYNC) issue_discard_thread - bdev_freeze - freeze_super - f2fs_stop_checkpoint() - f2fs_handle_critical_error - sb_start_write - set RO - waiting - bdev_thaw - thaw_super_locked - return -EINVAL, if sb_rdonly() - f2fs_stop_discard_thread -> wait for kthread_stop(discard_thread);

In the Linux kernel, the following vulnerability has been resolved: ext4: do not create EA inode under buffer lock ext4_xattr_set_entry() creates new EA inodes while holding buffer lock on the external xattr block. This is problematic as it nests all the allocation locking (which acquires locks on other buffers) under the buffer lock. This can even deadlock when the filesystem is corrupted and e.g. quota file is setup to contain xattr block as data block. Move the allocation of EA inode out of ext4_xattr_set_entry() into the callers.

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: Fix deadlock in ieee80211_sta_ps_deliver_wakeup() The ieee80211_sta_ps_deliver_wakeup() function takes sta->ps_lock to synchronizes with ieee80211_tx_h_unicast_ps_buf() which is called from softirq context. However using only spin_lock() to get sta->ps_lock in ieee80211_sta_ps_deliver_wakeup() does not prevent softirq to execute on this same CPU, to run ieee80211_tx_h_unicast_ps_buf() and try to take this same lock ending in deadlock. Below is an example of rcu stall that arises in such situation. rcu: INFO: rcu_sched self-detected stall on CPU rcu: 2-....: (42413413 ticks this GP) idle=b154/1/0x4000000000000000 softirq=1763/1765 fqs=21206996 rcu: (t=42586894 jiffies g=2057 q=362405 ncpus=4) CPU: 2 PID: 719 Comm: wpa_supplicant Tainted: G W 6.4.0-02158-g1b062f552873 #742 Hardware name: RPT (r1) (DT) pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : queued_spin_lock_slowpath+0x58/0x2d0 lr : invoke_tx_handlers_early+0x5b4/0x5c0 sp : ffff00001ef64660 x29: ffff00001ef64660 x28: ffff000009bc1070 x27: ffff000009bc0ad8 x26: ffff000009bc0900 x25: ffff00001ef647a8 x24: 0000000000000000 x23: ffff000009bc0900 x22: ffff000009bc0900 x21: ffff00000ac0e000 x20: ffff00000a279e00 x19: ffff00001ef646e8 x18: 0000000000000000 x17: ffff800016468000 x16: ffff00001ef608c0 x15: 0010533c93f64f80 x14: 0010395c9faa3946 x13: 0000000000000000 x12: 00000000fa83b2da x11: 000000012edeceea x10: ffff0000010fbe00 x9 : 0000000000895440 x8 : 000000000010533c x7 : ffff00000ad8b740 x6 : ffff00000c350880 x5 : 0000000000000007 x4 : 0000000000000001 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000001 x0 : ffff00000ac0e0e8 Call trace: queued_spin_lock_slowpath+0x58/0x2d0 ieee80211_tx+0x80/0x12c ieee80211_tx_pending+0x110/0x278 tasklet_action_common.constprop.0+0x10c/0x144 tasklet_action+0x20/0x28 _stext+0x11c/0x284 ____do_softirq+0xc/0x14 call_on_irq_stack+0x24/0x34 do_softirq_own_stack+0x18/0x20 do_softirq+0x74/0x7c __local_bh_enable_ip+0xa0/0xa4 _ieee80211_wake_txqs+0x3b0/0x4b8 __ieee80211_wake_queue+0x12c/0x168 ieee80211_add_pending_skbs+0xec/0x138 ieee80211_sta_ps_deliver_wakeup+0x2a4/0x480 ieee80211_mps_sta_status_update.part.0+0xd8/0x11c ieee80211_mps_sta_status_update+0x18/0x24 sta_apply_parameters+0x3bc/0x4c0 ieee80211_change_station+0x1b8/0x2dc nl80211_set_station+0x444/0x49c genl_family_rcv_msg_doit.isra.0+0xa4/0xfc genl_rcv_msg+0x1b0/0x244 netlink_rcv_skb+0x38/0x10c genl_rcv+0x34/0x48 netlink_unicast+0x254/0x2bc netlink_sendmsg+0x190/0x3b4 ____sys_sendmsg+0x1e8/0x218 ___sys_sendmsg+0x68/0x8c __sys_sendmsg+0x44/0x84 __arm64_sys_sendmsg+0x20/0x28 do_el0_svc+0x6c/0xe8 el0_svc+0x14/0x48 el0t_64_sync_handler+0xb0/0xb4 el0t_64_sync+0x14c/0x150 Using spin_lock_bh()/spin_unlock_bh() instead prevents softirq to raise on the same CPU that is holding the lock.

In the Linux kernel, the following vulnerability has been resolved: batman-adv: bypass empty buckets in batadv_purge_orig_ref() Many syzbot reports are pointing to soft lockups in batadv_purge_orig_ref() [1] Root cause is unknown, but we can avoid spending too much time there and perhaps get more interesting reports. [1] watchdog: BUG: soft lockup - CPU#0 stuck for 27s! [kworker/u4:6:621] Modules linked in: irq event stamp: 6182794 hardirqs last enabled at (6182793): [<ffff8000801dae10>] __local_bh_enable_ip+0x224/0x44c kernel/softirq.c:386 hardirqs last disabled at (6182794): [<ffff80008ad66a78>] __el1_irq arch/arm64/kernel/entry-common.c:533 [inline] hardirqs last disabled at (6182794): [<ffff80008ad66a78>] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:551 softirqs last enabled at (6182792): [<ffff80008aab71c4>] spin_unlock_bh include/linux/spinlock.h:396 [inline] softirqs last enabled at (6182792): [<ffff80008aab71c4>] batadv_purge_orig_ref+0x114c/0x1228 net/batman-adv/originator.c:1287 softirqs last disabled at (6182790): [<ffff80008aab61dc>] spin_lock_bh include/linux/spinlock.h:356 [inline] softirqs last disabled at (6182790): [<ffff80008aab61dc>] batadv_purge_orig_ref+0x164/0x1228 net/batman-adv/originator.c:1271 CPU: 0 PID: 621 Comm: kworker/u4:6 Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Workqueue: bat_events batadv_purge_orig pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : should_resched arch/arm64/include/asm/preempt.h:79 [inline] pc : __local_bh_enable_ip+0x228/0x44c kernel/softirq.c:388 lr : __local_bh_enable_ip+0x224/0x44c kernel/softirq.c:386 sp : ffff800099007970 x29: ffff800099007980 x28: 1fffe00018fce1bd x27: dfff800000000000 x26: ffff0000d2620008 x25: ffff0000c7e70de8 x24: 0000000000000001 x23: 1fffe00018e57781 x22: dfff800000000000 x21: ffff80008aab71c4 x20: ffff0001b40136c0 x19: ffff0000c72bbc08 x18: 1fffe0001a817bb0 x17: ffff800125414000 x16: ffff80008032116c x15: 0000000000000001 x14: 1fffe0001ee9d610 x13: 0000000000000000 x12: 0000000000000003 x11: 0000000000000000 x10: 0000000000ff0100 x9 : 0000000000000000 x8 : 00000000005e5789 x7 : ffff80008aab61dc x6 : 0000000000000000 x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000 x2 : 0000000000000006 x1 : 0000000000000080 x0 : ffff800125414000 Call trace: __daif_local_irq_enable arch/arm64/include/asm/irqflags.h:27 [inline] arch_local_irq_enable arch/arm64/include/asm/irqflags.h:49 [inline] __local_bh_enable_ip+0x228/0x44c kernel/softirq.c:386 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:167 [inline] _raw_spin_unlock_bh+0x3c/0x4c kernel/locking/spinlock.c:210 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_purge_orig_ref+0x114c/0x1228 net/batman-adv/originator.c:1287 batadv_purge_orig+0x20/0x70 net/batman-adv/originator.c:1300 process_one_work+0x694/0x1204 kernel/workqueue.c:2633 process_scheduled_works kernel/workqueue.c:2706 [inline] worker_thread+0x938/0xef4 kernel/workqueue.c:2787 kthread+0x288/0x310 kernel/kthread.c:388 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : arch_local_irq_enable+0x8/0xc arch/arm64/include/asm/irqflags.h:51 lr : default_idle_call+0xf8/0x128 kernel/sched/idle.c:103 sp : ffff800093a17d30 x29: ffff800093a17d30 x28: dfff800000000000 x27: 1ffff00012742fb4 x26: ffff80008ec9d000 x25: 0000000000000000 x24: 0000000000000002 x23: 1ffff00011d93a74 x22: ffff80008ec9d3a0 x21: 0000000000000000 x20: ffff0000c19dbc00 x19: ffff8000802d0fd8 x18: 1fffe00036804396 x17: ffff80008ec9d000 x16: ffff8000802d089c x15: 0000000000000001 ---truncated---

In the Linux kernel, the following vulnerability has been resolved: io_uring: fix possible deadlock in io_register_iowq_max_workers() The io_register_iowq_max_workers() function calls io_put_sq_data(), which acquires the sqd->lock without releasing the uring_lock. Similar to the commit 009ad9f0c6ee ("io_uring: drop ctx->uring_lock before acquiring sqd->lock"), this can lead to a potential deadlock situation. To resolve this issue, the uring_lock is released before calling io_put_sq_data(), and then it is re-acquired after the function call. This change ensures that the locks are acquired in the correct order, preventing the possibility of a deadlock.

In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: core: remove lock of otg mode during gadget suspend/resume to avoid deadlock When config CONFIG_USB_DWC3_DUAL_ROLE is selected, and trigger system to enter suspend status with below command: echo mem > /sys/power/state There will be a deadlock issue occurring. Detailed invoking path as below: dwc3_suspend_common() spin_lock_irqsave(&dwc->lock, flags); <-- 1st dwc3_gadget_suspend(dwc); dwc3_gadget_soft_disconnect(dwc); spin_lock_irqsave(&dwc->lock, flags); <-- 2nd This issue is exposed by commit c7ebd8149ee5 ("usb: dwc3: gadget: Fix NULL pointer dereference in dwc3_gadget_suspend") that removes the code of checking whether dwc->gadget_driver is NULL or not. It causes the following code is executed and deadlock occurs when trying to get the spinlock. In fact, the root cause is the commit 5265397f9442("usb: dwc3: Remove DWC3 locking during gadget suspend/resume") that forgot to remove the lock of otg mode. So, remove the redundant lock of otg mode during gadget suspend/resume.

In the Linux kernel, the following vulnerability has been resolved: ALSA: Fix deadlocks with kctl removals at disconnection In snd_card_disconnect(), we set card->shutdown flag at the beginning, call callbacks and do sync for card->power_ref_sleep waiters at the end. The callback may delete a kctl element, and this can lead to a deadlock when the device was in the suspended state. Namely: * A process waits for the power up at snd_power_ref_and_wait() in snd_ctl_info() or read/write() inside card->controls_rwsem. * The system gets disconnected meanwhile, and the driver tries to delete a kctl via snd_ctl_remove*(); it tries to take card->controls_rwsem again, but this is already locked by the above. Since the sleeper isn't woken up, this deadlocks. An easy fix is to wake up sleepers before processing the driver disconnect callbacks but right after setting the card->shutdown flag. Then all sleepers will abort immediately, and the code flows again. So, basically this patch moves the wait_event() call at the right timing. While we're at it, just to be sure, call wait_event_all() instead of wait_event(), although we don't use exclusive events on this queue for now.

In the Linux kernel, the following vulnerability has been resolved: RDMA/hns: Fix deadlock on SRQ async events. xa_lock for SRQ table may be required in AEQ. Use xa_store_irq()/ xa_erase_irq() to avoid deadlock.

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: team: prevent adding a device which is already a team device lower Prevent adding a device which is already a team device lower, e.g. adding veth0 if vlan1 was already added and veth0 is a lower of vlan1. This is not useful in practice and can lead to recursive locking: $ ip link add veth0 type veth peer name veth1 $ ip link set veth0 up $ ip link set veth1 up $ ip link add link veth0 name veth0.1 type vlan protocol 802.1Q id 1 $ ip link add team0 type team $ ip link set veth0.1 down $ ip link set veth0.1 master team0 team0: Port device veth0.1 added $ ip link set veth0 down $ ip link set veth0 master team0 ============================================ WARNING: possible recursive locking detected 6.13.0-rc2-virtme-00441-ga14a429069bb #46 Not tainted -------------------------------------------- ip/7684 is trying to acquire lock: ffff888016848e00 (team->team_lock_key){+.+.}-{4:4}, at: team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) but task is already holding lock: ffff888016848e00 (team->team_lock_key){+.+.}-{4:4}, at: team_add_slave (drivers/net/team/team_core.c:1147 drivers/net/team/team_core.c:1977) other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(team->team_lock_key); lock(team->team_lock_key); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by ip/7684: stack backtrace: CPU: 3 UID: 0 PID: 7684 Comm: ip Not tainted 6.13.0-rc2-virtme-00441-ga14a429069bb #46 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:122) print_deadlock_bug.cold (kernel/locking/lockdep.c:3040) __lock_acquire (kernel/locking/lockdep.c:3893 kernel/locking/lockdep.c:5226) ? netlink_broadcast_filtered (net/netlink/af_netlink.c:1548) lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 2)) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? lock_acquire (kernel/locking/lockdep.c:5822) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) __mutex_lock (kernel/locking/mutex.c:587 kernel/locking/mutex.c:735) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? fib_sync_up (net/ipv4/fib_semantics.c:2167) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) notifier_call_chain (kernel/notifier.c:85) call_netdevice_notifiers_info (net/core/dev.c:1996) __dev_notify_flags (net/core/dev.c:8993) ? __dev_change_flags (net/core/dev.c:8975) dev_change_flags (net/core/dev.c:9027) vlan_device_event (net/8021q/vlan.c:85 net/8021q/vlan.c:470) ? br_device_event (net/bridge/br.c:143) notifier_call_chain (kernel/notifier.c:85) call_netdevice_notifiers_info (net/core/dev.c:1996) dev_open (net/core/dev.c:1519 net/core/dev.c:1505) team_add_slave (drivers/net/team/team_core.c:1219 drivers/net/team/team_core.c:1977) ? __pfx_team_add_slave (drivers/net/team/team_core.c:1972) do_set_master (net/core/rtnetlink.c:2917) do_setlink.isra.0 (net/core/rtnetlink.c:3117)

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---

In the Linux kernel, the following vulnerability has been resolved: bpf: fix recursive lock when verdict program return SK_PASS When the stream_verdict program returns SK_PASS, it places the received skb into its own receive queue, but a recursive lock eventually occurs, leading to an operating system deadlock. This issue has been present since v6.9. ''' sk_psock_strp_data_ready write_lock_bh(&sk->sk_callback_lock) strp_data_ready strp_read_sock read_sock -> tcp_read_sock strp_recv cb.rcv_msg -> sk_psock_strp_read # now stream_verdict return SK_PASS without peer sock assign __SK_PASS = sk_psock_map_verd(SK_PASS, NULL) sk_psock_verdict_apply sk_psock_skb_ingress_self sk_psock_skb_ingress_enqueue sk_psock_data_ready read_lock_bh(&sk->sk_callback_lock) <= dead lock ''' This topic has been discussed before, but it has not been fixed. Previous discussion: https://lore.kernel.org/all/6684a5864ec86_403d20898@john.notmuch

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---

In the Linux kernel, the following vulnerability has been resolved: netfilter: IDLETIMER: Fix for possible ABBA deadlock Deletion of the last rule referencing a given idletimer may happen at the same time as a read of its file in sysfs: | ====================================================== | WARNING: possible circular locking dependency detected | 6.12.0-rc7-01692-g5e9a28f41134-dirty #594 Not tainted | ------------------------------------------------------ | iptables/3303 is trying to acquire lock: | ffff8881057e04b8 (kn->active#48){++++}-{0:0}, at: __kernfs_remove+0x20 | | but task is already holding lock: | ffffffffa0249068 (list_mutex){+.+.}-{3:3}, at: idletimer_tg_destroy_v] | | which lock already depends on the new lock. A simple reproducer is: | #!/bin/bash | | while true; do | iptables -A INPUT -i foo -j IDLETIMER --timeout 10 --label "testme" | iptables -D INPUT -i foo -j IDLETIMER --timeout 10 --label "testme" | done & | while true; do | cat /sys/class/xt_idletimer/timers/testme >/dev/null | done Avoid this by freeing list_mutex right after deleting the element from the list, then continuing with the teardown.

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: iso: Fix circular lock in iso_conn_big_sync This fixes the circular locking dependency warning below, by reworking iso_sock_recvmsg, to ensure that the socket lock is always released before calling a function that locks hdev. [ 561.670344] ====================================================== [ 561.670346] WARNING: possible circular locking dependency detected [ 561.670349] 6.12.0-rc6+ #26 Not tainted [ 561.670351] ------------------------------------------------------ [ 561.670353] iso-tester/3289 is trying to acquire lock: [ 561.670355] ffff88811f600078 (&hdev->lock){+.+.}-{3:3}, at: iso_conn_big_sync+0x73/0x260 [bluetooth] [ 561.670405] but task is already holding lock: [ 561.670407] ffff88815af58258 (sk_lock-AF_BLUETOOTH){+.+.}-{0:0}, at: iso_sock_recvmsg+0xbf/0x500 [bluetooth] [ 561.670450] which lock already depends on the new lock. [ 561.670452] the existing dependency chain (in reverse order) is: [ 561.670453] -> #2 (sk_lock-AF_BLUETOOTH){+.+.}-{0:0}: [ 561.670458] lock_acquire+0x7c/0xc0 [ 561.670463] lock_sock_nested+0x3b/0xf0 [ 561.670467] bt_accept_dequeue+0x1a5/0x4d0 [bluetooth] [ 561.670510] iso_sock_accept+0x271/0x830 [bluetooth] [ 561.670547] do_accept+0x3dd/0x610 [ 561.670550] __sys_accept4+0xd8/0x170 [ 561.670553] __x64_sys_accept+0x74/0xc0 [ 561.670556] x64_sys_call+0x17d6/0x25f0 [ 561.670559] do_syscall_64+0x87/0x150 [ 561.670563] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 561.670567] -> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}: [ 561.670571] lock_acquire+0x7c/0xc0 [ 561.670574] lock_sock_nested+0x3b/0xf0 [ 561.670577] iso_sock_listen+0x2de/0xf30 [bluetooth] [ 561.670617] __sys_listen_socket+0xef/0x130 [ 561.670620] __x64_sys_listen+0xe1/0x190 [ 561.670623] x64_sys_call+0x2517/0x25f0 [ 561.670626] do_syscall_64+0x87/0x150 [ 561.670629] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 561.670632] -> #0 (&hdev->lock){+.+.}-{3:3}: [ 561.670636] __lock_acquire+0x32ad/0x6ab0 [ 561.670639] lock_acquire.part.0+0x118/0x360 [ 561.670642] lock_acquire+0x7c/0xc0 [ 561.670644] __mutex_lock+0x18d/0x12f0 [ 561.670647] mutex_lock_nested+0x1b/0x30 [ 561.670651] iso_conn_big_sync+0x73/0x260 [bluetooth] [ 561.670687] iso_sock_recvmsg+0x3e9/0x500 [bluetooth] [ 561.670722] sock_recvmsg+0x1d5/0x240 [ 561.670725] sock_read_iter+0x27d/0x470 [ 561.670727] vfs_read+0x9a0/0xd30 [ 561.670731] ksys_read+0x1a8/0x250 [ 561.670733] __x64_sys_read+0x72/0xc0 [ 561.670736] x64_sys_call+0x1b12/0x25f0 [ 561.670738] do_syscall_64+0x87/0x150 [ 561.670741] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 561.670744] other info that might help us debug this: [ 561.670745] Chain exists of: &hdev->lock --> sk_lock-AF_BLUETOOTH-BTPROTO_ISO --> sk_lock-AF_BLUETOOTH [ 561.670751] Possible unsafe locking scenario: [ 561.670753] CPU0 CPU1 [ 561.670754] ---- ---- [ 561.670756] lock(sk_lock-AF_BLUETOOTH); [ 561.670758] lock(sk_lock AF_BLUETOOTH-BTPROTO_ISO); [ 561.670761] lock(sk_lock-AF_BLUETOOTH); [ 561.670764] lock(&hdev->lock); [ 561.670767] *** DEADLOCK ***

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: mm/thp: fix deferred split unqueue naming and locking Recent changes are putting more pressure on THP deferred split queues: under load revealing long-standing races, causing list_del corruptions, "Bad page state"s and worse (I keep BUGs in both of those, so usually don't get to see how badly they end up without). The relevant recent changes being 6.8's mTHP, 6.10's mTHP swapout, and 6.12's mTHP swapin, improved swap allocation, and underused THP splitting. Before fixing locking: rename misleading folio_undo_large_rmappable(), which does not undo large_rmappable, to folio_unqueue_deferred_split(), which is what it does. But that and its out-of-line __callee are mm internals of very limited usability: add comment and WARN_ON_ONCEs to check usage; and return a bool to say if a deferred split was unqueued, which can then be used in WARN_ON_ONCEs around safety checks (sparing callers the arcane conditionals in __folio_unqueue_deferred_split()). Just omit the folio_unqueue_deferred_split() from free_unref_folios(), all of whose callers now call it beforehand (and if any forget then bad_page() will tell) - except for its caller put_pages_list(), which itself no longer has any callers (and will be deleted separately). Swapout: mem_cgroup_swapout() has been resetting folio->memcg_data 0 without checking and unqueueing a THP folio from deferred split list; which is unfortunate, since the split_queue_lock depends on the memcg (when memcg is enabled); so swapout has been unqueueing such THPs later, when freeing the folio, using the pgdat's lock instead: potentially corrupting the memcg's list. __remove_mapping() has frozen refcount to 0 here, so no problem with calling folio_unqueue_deferred_split() before resetting memcg_data. That goes back to 5.4 commit 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware"): which included a check on swapcache before adding to deferred queue, but no check on deferred queue before adding THP to swapcache. That worked fine with the usual sequence of events in reclaim (though there were a couple of rare ways in which a THP on deferred queue could have been swapped out), but 6.12 commit dafff3f4c850 ("mm: split underused THPs") avoids splitting underused THPs in reclaim, which makes swapcache THPs on deferred queue commonplace. Keep the check on swapcache before adding to deferred queue? Yes: it is no longer essential, but preserves the existing behaviour, and is likely to be a worthwhile optimization (vmstat showed much more traffic on the queue under swapping load if the check was removed); update its comment. Memcg-v1 move (deprecated): mem_cgroup_move_account() has been changing folio->memcg_data without checking and unqueueing a THP folio from the deferred list, sometimes corrupting "from" memcg's list, like swapout. Refcount is non-zero here, so folio_unqueue_deferred_split() can only be used in a WARN_ON_ONCE to validate the fix, which must be done earlier: mem_cgroup_move_charge_pte_range() first try to split the THP (splitting of course unqueues), or skip it if that fails. Not ideal, but moving charge has been requested, and khugepaged should repair the THP later: nobody wants new custom unqueueing code just for this deprecated case. The 87eaceb3faa5 commit did have the code to move from one deferred list to another (but was not conscious of its unsafety while refcount non-0); but that was removed by 5.6 commit fac0516b5534 ("mm: thp: don't need care deferred split queue in memcg charge move path"), which argued that the existence of a PMD mapping guarantees that the THP cannot be on a deferred list. As above, false in rare cases, and now commonly false. Backport to 6.11 should be straightforward. Earlier backports must take care that other _deferred_list fixes and dependencies are included. There is not a strong case for backports, but they can fix cornercases.

In the Linux kernel, the following vulnerability has been resolved: drm/xe: Drop VM dma-resv lock on xe_sync_in_fence_get failure in exec IOCTL Upon failure all locks need to be dropped before returning to the user. (cherry picked from commit 7d1a4258e602ffdce529f56686925034c1b3b095)

In the Linux kernel, the following vulnerability has been resolved: vrf: revert "vrf: Remove unnecessary RCU-bh critical section" This reverts commit 504fc6f4f7f681d2a03aa5f68aad549d90eab853. dev_queue_xmit_nit is expected to be called with BH disabled. __dev_queue_xmit has the following: /* Disable soft irqs for various locks below. Also * stops preemption for RCU. */ rcu_read_lock_bh(); VRF must follow this invariant. The referenced commit removed this protection. Which triggered a lockdep warning: ================================ WARNING: inconsistent lock state 6.11.0 #1 Tainted: G W -------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. btserver/134819 [HC0[0]:SC0[0]:HE1:SE1] takes: ffff8882da30c118 (rlock-AF_PACKET){+.?.}-{2:2}, at: tpacket_rcv+0x863/0x3b30 {IN-SOFTIRQ-W} state was registered at: lock_acquire+0x19a/0x4f0 _raw_spin_lock+0x27/0x40 packet_rcv+0xa33/0x1320 __netif_receive_skb_core.constprop.0+0xcb0/0x3a90 __netif_receive_skb_list_core+0x2c9/0x890 netif_receive_skb_list_internal+0x610/0xcc0 [...] other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(rlock-AF_PACKET); <Interrupt> lock(rlock-AF_PACKET); *** DEADLOCK *** Call Trace: <TASK> dump_stack_lvl+0x73/0xa0 mark_lock+0x102e/0x16b0 __lock_acquire+0x9ae/0x6170 lock_acquire+0x19a/0x4f0 _raw_spin_lock+0x27/0x40 tpacket_rcv+0x863/0x3b30 dev_queue_xmit_nit+0x709/0xa40 vrf_finish_direct+0x26e/0x340 [vrf] vrf_l3_out+0x5f4/0xe80 [vrf] __ip_local_out+0x51e/0x7a0 [...]

In the Linux kernel, the following vulnerability has been resolved: tracing/timerlat: Drop interface_lock in stop_kthread() stop_kthread() is the offline callback for "trace/osnoise:online", since commit 5bfbcd1ee57b ("tracing/timerlat: Add interface_lock around clearing of kthread in stop_kthread()"), the following ABBA deadlock scenario is introduced: T1 | T2 [BP] | T3 [AP] osnoise_hotplug_workfn() | work_for_cpu_fn() | cpuhp_thread_fun() | _cpu_down() | osnoise_cpu_die() mutex_lock(&interface_lock) | | stop_kthread() | cpus_write_lock() | mutex_lock(&interface_lock) cpus_read_lock() | cpuhp_kick_ap() | As the interface_lock here in just for protecting the "kthread" field of the osn_var, use xchg() instead to fix this issue. Also use for_each_online_cpu() back in stop_per_cpu_kthreads() as it can take cpu_read_lock() again.

In the Linux kernel, the following vulnerability has been resolved: powerpc/qspinlock: Fix deadlock in MCS queue If an interrupt occurs in queued_spin_lock_slowpath() after we increment qnodesp->count and before node->lock is initialized, another CPU might see stale lock values in get_tail_qnode(). If the stale lock value happens to match the lock on that CPU, then we write to the "next" pointer of the wrong qnode. This causes a deadlock as the former CPU, once it becomes the head of the MCS queue, will spin indefinitely until it's "next" pointer is set by its successor in the queue. Running stress-ng on a 16 core (16EC/16VP) shared LPAR, results in occasional lockups similar to the following: $ stress-ng --all 128 --vm-bytes 80% --aggressive \ --maximize --oomable --verify --syslog \ --metrics --times --timeout 5m watchdog: CPU 15 Hard LOCKUP ...... NIP [c0000000000b78f4] queued_spin_lock_slowpath+0x1184/0x1490 LR [c000000001037c5c] _raw_spin_lock+0x6c/0x90 Call Trace: 0xc000002cfffa3bf0 (unreliable) _raw_spin_lock+0x6c/0x90 raw_spin_rq_lock_nested.part.135+0x4c/0xd0 sched_ttwu_pending+0x60/0x1f0 __flush_smp_call_function_queue+0x1dc/0x670 smp_ipi_demux_relaxed+0xa4/0x100 xive_muxed_ipi_action+0x20/0x40 __handle_irq_event_percpu+0x80/0x240 handle_irq_event_percpu+0x2c/0x80 handle_percpu_irq+0x84/0xd0 generic_handle_irq+0x54/0x80 __do_irq+0xac/0x210 __do_IRQ+0x74/0xd0 0x0 do_IRQ+0x8c/0x170 hardware_interrupt_common_virt+0x29c/0x2a0 --- interrupt: 500 at queued_spin_lock_slowpath+0x4b8/0x1490 ...... NIP [c0000000000b6c28] queued_spin_lock_slowpath+0x4b8/0x1490 LR [c000000001037c5c] _raw_spin_lock+0x6c/0x90 --- interrupt: 500 0xc0000029c1a41d00 (unreliable) _raw_spin_lock+0x6c/0x90 futex_wake+0x100/0x260 do_futex+0x21c/0x2a0 sys_futex+0x98/0x270 system_call_exception+0x14c/0x2f0 system_call_vectored_common+0x15c/0x2ec The following code flow illustrates how the deadlock occurs. For the sake of brevity, assume that both locks (A and B) are contended and we call the queued_spin_lock_slowpath() function. CPU0 CPU1 ---- ---- spin_lock_irqsave(A) | spin_unlock_irqrestore(A) | spin_lock(B) | | | ▼ | id = qnodesp->count++; | (Note that nodes[0].lock == A) | | | ▼ | Interrupt | (happens before "nodes[0].lock = B") | | | ▼ | spin_lock_irqsave(A) | | | ▼ | id = qnodesp->count++ | nodes[1].lock = A | | | ▼ | Tail of MCS queue | | spin_lock_irqsave(A) ▼ | Head of MCS queue ▼ | CPU0 is previous tail ▼ | Spin indefinitely ▼ (until "nodes[1].next != NULL") prev = get_tail_qnode(A, CPU0) | ▼ prev == &qnodes[CPU0].nodes[0] (as qnodes ---truncated---

In the Linux kernel, the following vulnerability has been resolved: pinmux: Use sequential access to access desc->pinmux data When two client of the same gpio call pinctrl_select_state() for the same functionality, we are seeing NULL pointer issue while accessing desc->mux_owner. Let's say two processes A, B executing in pin_request() for the same pin and process A updates the desc->mux_usecount but not yet updated the desc->mux_owner while process B see the desc->mux_usecount which got updated by A path and further executes strcmp and while accessing desc->mux_owner it crashes with NULL pointer. Serialize the access to mux related setting with a mutex lock. cpu0 (process A) cpu1(process B) pinctrl_select_state() { pinctrl_select_state() { pin_request() { pin_request() { ... .... } else { desc->mux_usecount++; desc->mux_usecount && strcmp(desc->mux_owner, owner)) { if (desc->mux_usecount > 1) return 0; desc->mux_owner = owner; } }

In the Linux kernel, the following vulnerability has been resolved: RDMA/hns: Fix spin_unlock_irqrestore() called with IRQs enabled Fix missuse of spin_lock_irq()/spin_unlock_irq() when spin_lock_irqsave()/spin_lock_irqrestore() was hold. This was discovered through the lock debugging, and the corresponding log is as follows: raw_local_irq_restore() called with IRQs enabled WARNING: CPU: 96 PID: 2074 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x30/0x40 ... Call trace: warn_bogus_irq_restore+0x30/0x40 _raw_spin_unlock_irqrestore+0x84/0xc8 add_qp_to_list+0x11c/0x148 [hns_roce_hw_v2] hns_roce_create_qp_common.constprop.0+0x240/0x780 [hns_roce_hw_v2] hns_roce_create_qp+0x98/0x160 [hns_roce_hw_v2] create_qp+0x138/0x258 ib_create_qp_kernel+0x50/0xe8 create_mad_qp+0xa8/0x128 ib_mad_port_open+0x218/0x448 ib_mad_init_device+0x70/0x1f8 add_client_context+0xfc/0x220 enable_device_and_get+0xd0/0x140 ib_register_device.part.0+0xf4/0x1c8 ib_register_device+0x34/0x50 hns_roce_register_device+0x174/0x3d0 [hns_roce_hw_v2] hns_roce_init+0xfc/0x2c0 [hns_roce_hw_v2] __hns_roce_hw_v2_init_instance+0x7c/0x1d0 [hns_roce_hw_v2] hns_roce_hw_v2_init_instance+0x9c/0x180 [hns_roce_hw_v2]

In the Linux kernel, the following vulnerability has been resolved: KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock Use a dedicated mutex to guard kvm_usage_count to fix a potential deadlock on x86 due to a chain of locks and SRCU synchronizations. Translating the below lockdep splat, CPU1 #6 will wait on CPU0 #1, CPU0 #8 will wait on CPU2 #3, and CPU2 #7 will wait on CPU1 #4 (if there's a writer, due to the fairness of r/w semaphores). CPU0 CPU1 CPU2 1 lock(&kvm->slots_lock); 2 lock(&vcpu->mutex); 3 lock(&kvm->srcu); 4 lock(cpu_hotplug_lock); 5 lock(kvm_lock); 6 lock(&kvm->slots_lock); 7 lock(cpu_hotplug_lock); 8 sync(&kvm->srcu); Note, there are likely more potential deadlocks in KVM x86, e.g. the same pattern of taking cpu_hotplug_lock outside of kvm_lock likely exists with __kvmclock_cpufreq_notifier(): cpuhp_cpufreq_online() | -> cpufreq_online() | -> cpufreq_gov_performance_limits() | -> __cpufreq_driver_target() | -> __target_index() | -> cpufreq_freq_transition_begin() | -> cpufreq_notify_transition() | -> ... __kvmclock_cpufreq_notifier() But, actually triggering such deadlocks is beyond rare due to the combination of dependencies and timings involved. E.g. the cpufreq notifier is only used on older CPUs without a constant TSC, mucking with the NX hugepage mitigation while VMs are running is very uncommon, and doing so while also onlining/offlining a CPU (necessary to generate contention on cpu_hotplug_lock) would be even more unusual. The most robust solution to the general cpu_hotplug_lock issue is likely to switch vm_list to be an RCU-protected list, e.g. so that x86's cpufreq notifier doesn't to take kvm_lock. For now, settle for fixing the most blatant deadlock, as switching to an RCU-protected list is a much more involved change, but add a comment in locking.rst to call out that care needs to be taken when walking holding kvm_lock and walking vm_list. ====================================================== WARNING: possible circular locking dependency detected 6.10.0-smp--c257535a0c9d-pip #330 Tainted: G S O ------------------------------------------------------ tee/35048 is trying to acquire lock: ff6a80eced71e0a8 (&kvm->slots_lock){+.+.}-{3:3}, at: set_nx_huge_pages+0x179/0x1e0 [kvm] but task is already holding lock: ffffffffc07abb08 (kvm_lock){+.+.}-{3:3}, at: set_nx_huge_pages+0x14a/0x1e0 [kvm] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (kvm_lock){+.+.}-{3:3}: __mutex_lock+0x6a/0xb40 mutex_lock_nested+0x1f/0x30 kvm_dev_ioctl+0x4fb/0xe50 [kvm] __se_sys_ioctl+0x7b/0xd0 __x64_sys_ioctl+0x21/0x30 x64_sys_call+0x15d0/0x2e60 do_syscall_64+0x83/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #2 (cpu_hotplug_lock){++++}-{0:0}: cpus_read_lock+0x2e/0xb0 static_key_slow_inc+0x16/0x30 kvm_lapic_set_base+0x6a/0x1c0 [kvm] kvm_set_apic_base+0x8f/0xe0 [kvm] kvm_set_msr_common+0x9ae/0xf80 [kvm] vmx_set_msr+0xa54/0xbe0 [kvm_intel] __kvm_set_msr+0xb6/0x1a0 [kvm] kvm_arch_vcpu_ioctl+0xeca/0x10c0 [kvm] kvm_vcpu_ioctl+0x485/0x5b0 [kvm] __se_sys_ioctl+0x7b/0xd0 __x64_sys_ioctl+0x21/0x30 x64_sys_call+0x15d0/0x2e60 do_syscall_64+0x83/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #1 (&kvm->srcu){.+.+}-{0:0}: __synchronize_srcu+0x44/0x1a0 ---truncated---

In the Linux kernel, the following vulnerability has been resolved: erofs: handle overlapped pclusters out of crafted images properly syzbot reported a task hang issue due to a deadlock case where it is waiting for the folio lock of a cached folio that will be used for cache I/Os. After looking into the crafted fuzzed image, I found it's formed with several overlapped big pclusters as below: Ext: logical offset | length : physical offset | length 0: 0.. 16384 | 16384 : 151552.. 167936 | 16384 1: 16384.. 32768 | 16384 : 155648.. 172032 | 16384 2: 32768.. 49152 | 16384 : 537223168.. 537239552 | 16384 ... Here, extent 0/1 are physically overlapped although it's entirely _impossible_ for normal filesystem images generated by mkfs. First, managed folios containing compressed data will be marked as up-to-date and then unlocked immediately (unlike in-place folios) when compressed I/Os are complete. If physical blocks are not submitted in the incremental order, there should be separate BIOs to avoid dependency issues. However, the current code mis-arranges z_erofs_fill_bio_vec() and BIO submission which causes unexpected BIO waits. Second, managed folios will be connected to their own pclusters for efficient inter-queries. However, this is somewhat hard to implement easily if overlapped big pclusters exist. Again, these only appear in fuzzed images so let's simply fall back to temporary short-lived pages for correctness. Additionally, it justifies that referenced managed folios cannot be truncated for now and reverts part of commit 2080ca1ed3e4 ("erofs: tidy up `struct z_erofs_bvec`") for simplicity although it shouldn't be any difference.