A use-after-free flaw was found in the Linux kernel’s core dump subsystem. This flaw allows a local user to crash the system. Only if patch 390031c94211 ("coredump: Use the vma snapshot in fill_files_note") not applied yet, then kernel could be affected.

In the Linux kernel, the following vulnerability has been resolved: soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free A recent DRM series purporting to simplify support for "transparent bridges" and handling of probe deferrals ironically exposed a use-after-free issue on pmic_glink_altmode probe deferral. This has manifested itself as the display subsystem occasionally failing to initialise and NULL-pointer dereferences during boot of machines like the Lenovo ThinkPad X13s. Specifically, the dp-hpd bridge is currently registered before all resources have been acquired which means that it can also be deregistered on probe deferrals. In the meantime there is a race window where the new aux bridge driver (or PHY driver previously) may have looked up the dp-hpd bridge and stored a (non-reference-counted) pointer to the bridge which is about to be deallocated. When the display controller is later initialised, this triggers a use-after-free when attaching the bridges: dp -> aux -> dp-hpd (freed) which may, for example, result in the freed bridge failing to attach: [drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16 or a NULL-pointer dereference: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 ... Call trace: drm_bridge_attach+0x70/0x1a8 [drm] drm_aux_bridge_attach+0x24/0x38 [aux_bridge] drm_bridge_attach+0x80/0x1a8 [drm] dp_bridge_init+0xa8/0x15c [msm] msm_dp_modeset_init+0x28/0xc4 [msm] The DRM bridge implementation is clearly fragile and implicitly built on the assumption that bridges may never go away. In this case, the fix is to move the bridge registration in the pmic_glink_altmode driver to after all resources have been looked up. Incidentally, with the new dp-hpd bridge implementation, which registers child devices, this is also a requirement due to a long-standing issue in driver core that can otherwise lead to a probe deferral loop (see commit fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")). [DB: slightly fixed commit message by adding the word 'commit']

In the Linux kernel, the following vulnerability has been resolved: spi: lpspi: Avoid potential use-after-free in probe() fsl_lpspi_probe() is allocating/disposing memory manually with spi_alloc_host()/spi_alloc_target(), but uses devm_spi_register_controller(). In case of error after the latter call the memory will be explicitly freed in the probe function by spi_controller_put() call, but used afterwards by "devm" management outside probe() (spi_unregister_controller() <- devm_spi_unregister() below). Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070 ... Call trace: kernfs_find_ns kernfs_find_and_get_ns sysfs_remove_group sysfs_remove_groups device_remove_attrs device_del spi_unregister_controller devm_spi_unregister release_nodes devres_release_all really_probe driver_probe_device __device_attach_driver bus_for_each_drv __device_attach device_initial_probe bus_probe_device deferred_probe_work_func process_one_work worker_thread kthread ret_from_fork

In the Linux kernel, the following vulnerability has been resolved: net: atlantic: Fix DMA mapping for PTP hwts ring Function aq_ring_hwts_rx_alloc() maps extra AQ_CFG_RXDS_DEF bytes for PTP HWTS ring but then generic aq_ring_free() does not take this into account. Create and use a specific function to free HWTS ring to fix this issue. Trace: [ 215.351607] ------------[ cut here ]------------ [ 215.351612] DMA-API: atlantic 0000:4b:00.0: device driver frees DMA memory with different size [device address=0x00000000fbdd0000] [map size=34816 bytes] [unmap size=32768 bytes] [ 215.351635] WARNING: CPU: 33 PID: 10759 at kernel/dma/debug.c:988 check_unmap+0xa6f/0x2360 ... [ 215.581176] Call Trace: [ 215.583632] <TASK> [ 215.585745] ? show_trace_log_lvl+0x1c4/0x2df [ 215.590114] ? show_trace_log_lvl+0x1c4/0x2df [ 215.594497] ? debug_dma_free_coherent+0x196/0x210 [ 215.599305] ? check_unmap+0xa6f/0x2360 [ 215.603147] ? __warn+0xca/0x1d0 [ 215.606391] ? check_unmap+0xa6f/0x2360 [ 215.610237] ? report_bug+0x1ef/0x370 [ 215.613921] ? handle_bug+0x3c/0x70 [ 215.617423] ? exc_invalid_op+0x14/0x50 [ 215.621269] ? asm_exc_invalid_op+0x16/0x20 [ 215.625480] ? check_unmap+0xa6f/0x2360 [ 215.629331] ? mark_lock.part.0+0xca/0xa40 [ 215.633445] debug_dma_free_coherent+0x196/0x210 [ 215.638079] ? __pfx_debug_dma_free_coherent+0x10/0x10 [ 215.643242] ? slab_free_freelist_hook+0x11d/0x1d0 [ 215.648060] dma_free_attrs+0x6d/0x130 [ 215.651834] aq_ring_free+0x193/0x290 [atlantic] [ 215.656487] aq_ptp_ring_free+0x67/0x110 [atlantic] ... [ 216.127540] ---[ end trace 6467e5964dd2640b ]--- [ 216.132160] DMA-API: Mapped at: [ 216.132162] debug_dma_alloc_coherent+0x66/0x2f0 [ 216.132165] dma_alloc_attrs+0xf5/0x1b0 [ 216.132168] aq_ring_hwts_rx_alloc+0x150/0x1f0 [atlantic] [ 216.132193] aq_ptp_ring_alloc+0x1bb/0x540 [atlantic] [ 216.132213] aq_nic_init+0x4a1/0x760 [atlantic]

In the Linux kernel, the following vulnerability has been resolved: RDMA/irdma: Fix KASAN issue with tasklet KASAN testing revealed the following issue assocated with freeing an IRQ. [50006.466686] Call Trace: [50006.466691] <IRQ> [50006.489538] dump_stack+0x5c/0x80 [50006.493475] print_address_description.constprop.6+0x1a/0x150 [50006.499872] ? irdma_sc_process_ceq+0x483/0x790 [irdma] [50006.505742] ? irdma_sc_process_ceq+0x483/0x790 [irdma] [50006.511644] kasan_report.cold.11+0x7f/0x118 [50006.516572] ? irdma_sc_process_ceq+0x483/0x790 [irdma] [50006.522473] irdma_sc_process_ceq+0x483/0x790 [irdma] [50006.528232] irdma_process_ceq+0xb2/0x400 [irdma] [50006.533601] ? irdma_hw_flush_wqes_callback+0x370/0x370 [irdma] [50006.540298] irdma_ceq_dpc+0x44/0x100 [irdma] [50006.545306] tasklet_action_common.isra.14+0x148/0x2c0 [50006.551096] __do_softirq+0x1d0/0xaf8 [50006.555396] irq_exit_rcu+0x219/0x260 [50006.559670] irq_exit+0xa/0x20 [50006.563320] smp_apic_timer_interrupt+0x1bf/0x690 [50006.568645] apic_timer_interrupt+0xf/0x20 [50006.573341] </IRQ> The issue is that a tasklet could be pending on another core racing the delete of the irq. Fix by insuring any scheduled tasklet is killed after deleting the irq.

A use-after-free flaw was found in reconn_set_ipaddr_from_hostname in fs/cifs/connect.c in the Linux kernel. The issue occurs when it forgets to set the free pointer server->hostname to NULL, leading to an invalid pointer request.

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel The following race is possible between bpf_timer_cancel_and_free and bpf_timer_cancel. It will lead a UAF on the timer->timer. bpf_timer_cancel(); spin_lock(); t = timer->time; spin_unlock(); bpf_timer_cancel_and_free(); spin_lock(); t = timer->timer; timer->timer = NULL; spin_unlock(); hrtimer_cancel(&t->timer); kfree(t); /* UAF on t */ hrtimer_cancel(&t->timer); In bpf_timer_cancel_and_free, this patch frees the timer->timer after a rcu grace period. This requires a rcu_head addition to the "struct bpf_hrtimer". Another kfree(t) happens in bpf_timer_init, this does not need a kfree_rcu because it is still under the spin_lock and timer->timer has not been visible by others yet. In bpf_timer_cancel, rcu_read_lock() is added because this helper can be used in a non rcu critical section context (e.g. from a sleepable bpf prog). Other timer->timer usages in helpers.c have been audited, bpf_timer_cancel() is the only place where timer->timer is used outside of the spin_lock. Another solution considered is to mark a t->flag in bpf_timer_cancel and clear it after hrtimer_cancel() is done. In bpf_timer_cancel_and_free, it busy waits for the flag to be cleared before kfree(t). This patch goes with a straight forward solution and frees timer->timer after a rcu grace period.

A use-after-free flaw was found in io_uring/filetable.c in io_install_fixed_file in the io_uring subcomponent in the Linux Kernel during call cleanup. This flaw may lead to a denial of service.

In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: fix possible use-after-free and null-ptr-deref The pernet operations structure for the subsystem must be registered before registering the generic netlink family.

In the Linux kernel, the following vulnerability has been resolved: vdpa: fix use-after-free on vp_vdpa_remove When vp_vdpa driver is unbind, vp_vdpa is freed in vdpa_unregister_device and then vp_vdpa->mdev.pci_dev is dereferenced in vp_modern_remove, triggering use-after-free. Call Trace of unbinding driver free vp_vdpa : do_syscall_64 vfs_write kernfs_fop_write_iter device_release_driver_internal pci_device_remove vp_vdpa_remove vdpa_unregister_device kobject_release device_release kfree Call Trace of dereference vp_vdpa->mdev.pci_dev: vp_modern_remove pci_release_selected_regions pci_release_region pci_resource_len pci_resource_end (dev)->resource[(bar)].end

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_queue: fix possible use-after-free Eric Dumazet says: The sock_hold() side seems suspect, because there is no guarantee that sk_refcnt is not already 0. On failure, we cannot queue the packet and need to indicate an error. The packet will be dropped by the caller. v2: split skb prefetch hunk into separate change

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: Fix leaking sent_cmd skb sent_cmd memory is not freed before freeing hci_dev causing it to leak it contents.

In the Linux kernel through 6.7.1, there is a use-after-free in cec_queue_msg_fh, related to drivers/media/cec/core/cec-adap.c and drivers/media/cec/core/cec-api.c.

A use-after-free flaw was found in lan78xx_disconnect in drivers/net/usb/lan78xx.c in the network sub-component, net/usb/lan78xx in the Linux Kernel. This flaw allows a local attacker to crash the system when the LAN78XX USB device detaches.

In the Linux kernel, the following vulnerability has been resolved: drm/i915: Fix potential context UAFs gem_context_register() makes the context visible to userspace, and which point a separate thread can trigger the I915_GEM_CONTEXT_DESTROY ioctl. So we need to ensure that nothing uses the ctx ptr after this. And we need to ensure that adding the ctx to the xarray is the *last* thing that gem_context_register() does with the ctx pointer. [tursulin: Stable and fixes tags add/tidy.] (cherry picked from commit bed4b455cf5374e68879be56971c1da563bcd90c)

In the Linux kernel, the following vulnerability has been resolved: nfc: pn533: Wait for out_urb's completion in pn533_usb_send_frame() Fix a use-after-free that occurs in hcd when in_urb sent from pn533_usb_send_frame() is completed earlier than out_urb. Its callback frees the skb data in pn533_send_async_complete() that is used as a transfer buffer of out_urb. Wait before sending in_urb until the callback of out_urb is called. To modify the callback of out_urb alone, separate the complete function of out_urb and ack_urb. Found by a modified version of syzkaller. BUG: KASAN: use-after-free in dummy_timer Call Trace: memcpy (mm/kasan/shadow.c:65) dummy_perform_transfer (drivers/usb/gadget/udc/dummy_hcd.c:1352) transfer (drivers/usb/gadget/udc/dummy_hcd.c:1453) dummy_timer (drivers/usb/gadget/udc/dummy_hcd.c:1972) arch_static_branch (arch/x86/include/asm/jump_label.h:27) static_key_false (include/linux/jump_label.h:207) timer_expire_exit (include/trace/events/timer.h:127) call_timer_fn (kernel/time/timer.c:1475) expire_timers (kernel/time/timer.c:1519) __run_timers (kernel/time/timer.c:1790) run_timer_softirq (kernel/time/timer.c:1803)

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential use after free in nilfs_gccache_submit_read_data() In nilfs_gccache_submit_read_data(), brelse(bh) is called to drop the reference count of bh when the call to nilfs_dat_translate() fails. If the reference count hits 0 and its owner page gets unlocked, bh may be freed. However, bh->b_page is dereferenced to put the page after that, which may result in a use-after-free bug. This patch moves the release operation after unlocking and putting the page. NOTE: The function in question is only called in GC, and in combination with current userland tools, address translation using DAT does not occur in that function, so the code path that causes this issue will not be executed. However, it is possible to run that code path by intentionally modifying the userland GC library or by calling the GC ioctl directly. [konishi.ryusuke@gmail.com: NOTE added to the commit log]

In the Linux kernel, the following vulnerability has been resolved: mm/migrate_device: don't add folio to be freed to LRU in migrate_device_finalize() If migration succeeded, we called folio_migrate_flags()->mem_cgroup_migrate() to migrate the memcg from the old to the new folio. This will set memcg_data of the old folio to 0. Similarly, if migration failed, memcg_data of the dst folio is left unset. If we call folio_putback_lru() on such folios (memcg_data == 0), we will add the folio to be freed to the LRU, making memcg code unhappy. Running the hmm selftests: # ./hmm-tests ... # RUN hmm.hmm_device_private.migrate ... [ 102.078007][T14893] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x7ff27d200 pfn:0x13cc00 [ 102.079974][T14893] anon flags: 0x17ff00000020018(uptodate|dirty|swapbacked|node=0|zone=2|lastcpupid=0x7ff) [ 102.082037][T14893] raw: 017ff00000020018 dead000000000100 dead000000000122 ffff8881353896c9 [ 102.083687][T14893] raw: 00000007ff27d200 0000000000000000 00000001ffffffff 0000000000000000 [ 102.085331][T14893] page dumped because: VM_WARN_ON_ONCE_FOLIO(!memcg && !mem_cgroup_disabled()) [ 102.087230][T14893] ------------[ cut here ]------------ [ 102.088279][T14893] WARNING: CPU: 0 PID: 14893 at ./include/linux/memcontrol.h:726 folio_lruvec_lock_irqsave+0x10e/0x170 [ 102.090478][T14893] Modules linked in: [ 102.091244][T14893] CPU: 0 UID: 0 PID: 14893 Comm: hmm-tests Not tainted 6.13.0-09623-g6c216bc522fd #151 [ 102.093089][T14893] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014 [ 102.094848][T14893] RIP: 0010:folio_lruvec_lock_irqsave+0x10e/0x170 [ 102.096104][T14893] Code: ... [ 102.099908][T14893] RSP: 0018:ffffc900236c37b0 EFLAGS: 00010293 [ 102.101152][T14893] RAX: 0000000000000000 RBX: ffffea0004f30000 RCX: ffffffff8183f426 [ 102.102684][T14893] RDX: ffff8881063cb880 RSI: ffffffff81b8117f RDI: ffff8881063cb880 [ 102.104227][T14893] RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 [ 102.105757][T14893] R10: 0000000000000001 R11: 0000000000000002 R12: ffffc900236c37d8 [ 102.107296][T14893] R13: ffff888277a2bcb0 R14: 000000000000001f R15: 0000000000000000 [ 102.108830][T14893] FS: 00007ff27dbdd740(0000) GS:ffff888277a00000(0000) knlGS:0000000000000000 [ 102.110643][T14893] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 102.111924][T14893] CR2: 00007ff27d400000 CR3: 000000010866e000 CR4: 0000000000750ef0 [ 102.113478][T14893] PKRU: 55555554 [ 102.114172][T14893] Call Trace: [ 102.114805][T14893] <TASK> [ 102.115397][T14893] ? folio_lruvec_lock_irqsave+0x10e/0x170 [ 102.116547][T14893] ? __warn.cold+0x110/0x210 [ 102.117461][T14893] ? folio_lruvec_lock_irqsave+0x10e/0x170 [ 102.118667][T14893] ? report_bug+0x1b9/0x320 [ 102.119571][T14893] ? handle_bug+0x54/0x90 [ 102.120494][T14893] ? exc_invalid_op+0x17/0x50 [ 102.121433][T14893] ? asm_exc_invalid_op+0x1a/0x20 [ 102.122435][T14893] ? __wake_up_klogd.part.0+0x76/0xd0 [ 102.123506][T14893] ? dump_page+0x4f/0x60 [ 102.124352][T14893] ? folio_lruvec_lock_irqsave+0x10e/0x170 [ 102.125500][T14893] folio_batch_move_lru+0xd4/0x200 [ 102.126577][T14893] ? __pfx_lru_add+0x10/0x10 [ 102.127505][T14893] __folio_batch_add_and_move+0x391/0x720 [ 102.128633][T14893] ? __pfx_lru_add+0x10/0x10 [ 102.129550][T14893] folio_putback_lru+0x16/0x80 [ 102.130564][T14893] migrate_device_finalize+0x9b/0x530 [ 102.131640][T14893] dmirror_migrate_to_device.constprop.0+0x7c5/0xad0 [ 102.133047][T14893] dmirror_fops_unlocked_ioctl+0x89b/0xc80 Likely, nothing else goes wrong: putting the last folio reference will remove the folio from the LRU again. So besides memcg complaining, adding the folio to be freed to the LRU is just an unnecessary step. The new flow resembles what we have in migrate_folio_move(): add the dst to the lru, rem ---truncated---

An issue was discovered in the Linux kernel 5.10.x before 5.10.155. A use-after-free in io_sqpoll_wait_sq in fs/io_uring.c allows an attacker to crash the kernel, resulting in denial of service. finish_wait can be skipped. An attack can occur in some situations by forking a process and then quickly terminating it. NOTE: later kernel versions, such as the 5.15 longterm series, substantially changed the implementation of io_sqpoll_wait_sq.

A use-after-free vulnerability was found in the siano smsusb module in the Linux kernel. The bug occurs during device initialization when the siano device is plugged in. This flaw allows a local user to crash the system, causing a denial of service condition.

An issue was discovered in the Linux kernel through 6.4.2. A crafted UDF filesystem image causes a use-after-free write operation in the udf_put_super and udf_close_lvid functions in fs/udf/super.c. NOTE: the suse.com reference has a different perspective about this.

A flaw was found in the Linux kernel's implementation of GRO in versions before 5.2. This flaw allows an attacker with local access to crash the system.

The __do_follow_link function in fs/namei.c in the Linux kernel before 2.6.33 does not properly handle the last pathname component during use of certain filesystems, which allows local users to cause a denial of service (incorrect free operations and system crash) via an open system call.

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix management of listener transports Currently, when no active threads are running, a root user using nfsdctl command can try to remove a particular listener from the list of previously added ones, then start the server by increasing the number of threads, it leads to the following problem: [ 158.835354] refcount_t: addition on 0; use-after-free. [ 158.835603] WARNING: CPU: 2 PID: 9145 at lib/refcount.c:25 refcount_warn_saturate+0x160/0x1a0 [ 158.836017] Modules linked in: rpcrdma rdma_cm iw_cm ib_cm ib_core nfsd auth_rpcgss nfs_acl lockd grace overlay isofs uinput snd_seq_dummy snd_hrtimer nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 rfkill ip_set nf_tables qrtr sunrpc vfat fat uvcvideo videobuf2_vmalloc videobuf2_memops uvc videobuf2_v4l2 videodev videobuf2_common snd_hda_codec_generic mc e1000e snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer snd soundcore sg loop dm_multipath dm_mod nfnetlink vsock_loopback vmw_vsock_virtio_transport_common vmw_vsock_vmci_transport vmw_vmci vsock xfs libcrc32c crct10dif_ce ghash_ce vmwgfx sha2_ce sha256_arm64 sr_mod sha1_ce cdrom nvme drm_client_lib drm_ttm_helper ttm nvme_core drm_kms_helper nvme_auth drm fuse [ 158.840093] CPU: 2 UID: 0 PID: 9145 Comm: nfsd Kdump: loaded Tainted: G B W 6.13.0-rc6+ #7 [ 158.840624] Tainted: [B]=BAD_PAGE, [W]=WARN [ 158.840802] Hardware name: VMware, Inc. VMware20,1/VBSA, BIOS VMW201.00V.24006586.BA64.2406042154 06/04/2024 [ 158.841220] pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) [ 158.841563] pc : refcount_warn_saturate+0x160/0x1a0 [ 158.841780] lr : refcount_warn_saturate+0x160/0x1a0 [ 158.842000] sp : ffff800089be7d80 [ 158.842147] x29: ffff800089be7d80 x28: ffff00008e68c148 x27: ffff00008e68c148 [ 158.842492] x26: ffff0002e3b5c000 x25: ffff600011cd1829 x24: ffff00008653c010 [ 158.842832] x23: ffff00008653c000 x22: 1fffe00011cd1829 x21: ffff00008653c028 [ 158.843175] x20: 0000000000000002 x19: ffff00008653c010 x18: 0000000000000000 [ 158.843505] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 [ 158.843836] x14: 0000000000000000 x13: 0000000000000001 x12: ffff600050a26493 [ 158.844143] x11: 1fffe00050a26492 x10: ffff600050a26492 x9 : dfff800000000000 [ 158.844475] x8 : 00009fffaf5d9b6e x7 : ffff000285132493 x6 : 0000000000000001 [ 158.844823] x5 : ffff000285132490 x4 : ffff600050a26493 x3 : ffff8000805e72bc [ 158.845174] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000098588000 [ 158.845528] Call trace: [ 158.845658] refcount_warn_saturate+0x160/0x1a0 (P) [ 158.845894] svc_recv+0x58c/0x680 [sunrpc] [ 158.846183] nfsd+0x1fc/0x348 [nfsd] [ 158.846390] kthread+0x274/0x2f8 [ 158.846546] ret_from_fork+0x10/0x20 [ 158.846714] ---[ end trace 0000000000000000 ]--- nfsd_nl_listener_set_doit() would manipulate the list of transports of server's sv_permsocks and close the specified listener but the other list of transports (server's sp_xprts list) would not be changed leading to the problem above. Instead, determined if the nfsdctl is trying to remove a listener, in which case, delete all the existing listener transports and re-create all-but-the-removed ones.

In the Linux kernel, the following vulnerability has been resolved: btrfs: wait for fixup workers before stopping cleaner kthread during umount During unmount, at close_ctree(), we have the following steps in this order: 1) Park the cleaner kthread - this doesn't destroy the kthread, it basically halts its execution (wake ups against it work but do nothing); 2) We stop the cleaner kthread - this results in freeing the respective struct task_struct; 3) We call btrfs_stop_all_workers() which waits for any jobs running in all the work queues and then free the work queues. Syzbot reported a case where a fixup worker resulted in a crash when doing a delayed iput on its inode while attempting to wake up the cleaner at btrfs_add_delayed_iput(), because the task_struct of the cleaner kthread was already freed. This can happen during unmount because we don't wait for any fixup workers still running before we call kthread_stop() against the cleaner kthread, which stops and free all its resources. Fix this by waiting for any fixup workers at close_ctree() before we call kthread_stop() against the cleaner and run pending delayed iputs. The stack traces reported by syzbot were the following: BUG: KASAN: slab-use-after-free in __lock_acquire+0x77/0x2050 kernel/locking/lockdep.c:5065 Read of size 8 at addr ffff8880272a8a18 by task kworker/u8:3/52 CPU: 1 UID: 0 PID: 52 Comm: kworker/u8:3 Not tainted 6.12.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: btrfs-fixup btrfs_work_helper Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 __lock_acquire+0x77/0x2050 kernel/locking/lockdep.c:5065 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162 class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline] try_to_wake_up+0xb0/0x1480 kernel/sched/core.c:4154 btrfs_writepage_fixup_worker+0xc16/0xdf0 fs/btrfs/inode.c:2842 btrfs_work_helper+0x390/0xc50 fs/btrfs/async-thread.c:314 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 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 </TASK> Allocated by task 2: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:319 [inline] __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345 kasan_slab_alloc include/linux/kasan.h:247 [inline] slab_post_alloc_hook mm/slub.c:4086 [inline] slab_alloc_node mm/slub.c:4135 [inline] kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4187 alloc_task_struct_node kernel/fork.c:180 [inline] dup_task_struct+0x57/0x8c0 kernel/fork.c:1107 copy_process+0x5d1/0x3d50 kernel/fork.c:2206 kernel_clone+0x223/0x880 kernel/fork.c:2787 kernel_thread+0x1bc/0x240 kernel/fork.c:2849 create_kthread kernel/kthread.c:412 [inline] kthreadd+0x60d/0x810 kernel/kthread.c:765 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Freed by task 61: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_h ---truncated---

In drivers/media/dvb-core/dmxdev.c in the Linux kernel through 5.19.10, there is a use-after-free caused by refcount races, affecting dvb_demux_open and dvb_dmxdev_release.

A use-after-free(UAF) vulnerability was found in function 'vmw_execbuf_tie_context' in drivers/gpu/vmxgfx/vmxgfx_execbuf.c in Linux kernel's vmwgfx driver with device file '/dev/dri/renderD128 (or Dxxx)'. This flaw allows a local attacker with a user account on the system to gain privilege, causing a denial of service(DoS).

A use-after-free(UAF) vulnerability was found in function 'vmw_cmd_res_check' in drivers/gpu/vmxgfx/vmxgfx_execbuf.c in Linux kernel's vmwgfx driver with device file '/dev/dri/renderD128 (or Dxxx)'. This flaw allows a local attacker with a user account on the system to gain privilege, causing a denial of service(DoS).

A flaw was found in the Linux kernel’s networking code. A use-after-free was found in the way the sch_sfb enqueue function used the socket buffer (SKB) cb field after the same SKB had been enqueued (and freed) into a child qdisc. This flaw allows a local, unprivileged user to crash the system, causing a denial of service.

In the Linux kernel, the following vulnerability has been resolved: scsi: qla2xxx: Fix use after free on unload System crash is observed with stack trace warning of use after free. There are 2 signals to tell dpc_thread to terminate (UNLOADING flag and kthread_stop). On setting the UNLOADING flag when dpc_thread happens to run at the time and sees the flag, this causes dpc_thread to exit and clean up itself. When kthread_stop is called for final cleanup, this causes use after free. Remove UNLOADING signal to terminate dpc_thread. Use the kthread_stop as the main signal to exit dpc_thread. [596663.812935] kernel BUG at mm/slub.c:294! [596663.812950] invalid opcode: 0000 [#1] SMP PTI [596663.812957] CPU: 13 PID: 1475935 Comm: rmmod Kdump: loaded Tainted: G IOE --------- - - 4.18.0-240.el8.x86_64 #1 [596663.812960] Hardware name: HP ProLiant DL380p Gen8, BIOS P70 08/20/2012 [596663.812974] RIP: 0010:__slab_free+0x17d/0x360 ... [596663.813008] Call Trace: [596663.813022] ? __dentry_kill+0x121/0x170 [596663.813030] ? _cond_resched+0x15/0x30 [596663.813034] ? _cond_resched+0x15/0x30 [596663.813039] ? wait_for_completion+0x35/0x190 [596663.813048] ? try_to_wake_up+0x63/0x540 [596663.813055] free_task+0x5a/0x60 [596663.813061] kthread_stop+0xf3/0x100 [596663.813103] qla2x00_remove_one+0x284/0x440 [qla2xxx]

In the Linux kernel, the following vulnerability has been resolved: iommu/s390: Implement blocking domain This fixes a crash when surprise hot-unplugging a PCI device. This crash happens because during hot-unplug __iommu_group_set_domain_nofail() attaching the default domain fails when the platform no longer recognizes the device as it has already been removed and we end up with a NULL domain pointer and UAF. This is exactly the case referred to in the second comment in __iommu_device_set_domain() and just as stated there if we can instead attach the blocking domain the UAF is prevented as this can handle the already removed device. Implement the blocking domain to use this handling. With this change, the crash is fixed but we still hit a warning attempting to change DMA ownership on a blocked device.

In the Linux kernel, the following vulnerability has been resolved: net: microchip: vcap api: Fix memory leaks in vcap_api_encode_rule_test() Commit a3c1e45156ad ("net: microchip: vcap: Fix use-after-free error in kunit test") fixed the use-after-free error, but introduced below memory leaks by removing necessary vcap_free_rule(), add it to fix it. unreferenced object 0xffffff80ca58b700 (size 192): comm "kunit_try_catch", pid 1215, jiffies 4294898264 hex dump (first 32 bytes): 00 12 7a 00 05 00 00 00 0a 00 00 00 64 00 00 00 ..z.........d... 00 00 00 00 00 00 00 00 00 04 0b cc 80 ff ff ff ................ backtrace (crc 9c09c3fe): [<0000000052a0be73>] kmemleak_alloc+0x34/0x40 [<0000000043605459>] __kmalloc_cache_noprof+0x26c/0x2f4 [<0000000040a01b8d>] vcap_alloc_rule+0x3cc/0x9c4 [<000000003fe86110>] vcap_api_encode_rule_test+0x1ac/0x16b0 [<00000000b3595fc4>] kunit_try_run_case+0x13c/0x3ac [<0000000010f5d2bf>] kunit_generic_run_threadfn_adapter+0x80/0xec [<00000000c5d82c9a>] kthread+0x2e8/0x374 [<00000000f4287308>] ret_from_fork+0x10/0x20 unreferenced object 0xffffff80cc0b0400 (size 64): comm "kunit_try_catch", pid 1215, jiffies 4294898265 hex dump (first 32 bytes): 80 04 0b cc 80 ff ff ff 18 b7 58 ca 80 ff ff ff ..........X..... 39 00 00 00 02 00 00 00 06 05 04 03 02 01 ff ff 9............... backtrace (crc daf014e9): [<0000000052a0be73>] kmemleak_alloc+0x34/0x40 [<0000000043605459>] __kmalloc_cache_noprof+0x26c/0x2f4 [<000000000ff63fd4>] vcap_rule_add_key+0x2cc/0x528 [<00000000dfdb1e81>] vcap_api_encode_rule_test+0x224/0x16b0 [<00000000b3595fc4>] kunit_try_run_case+0x13c/0x3ac [<0000000010f5d2bf>] kunit_generic_run_threadfn_adapter+0x80/0xec [<00000000c5d82c9a>] kthread+0x2e8/0x374 [<00000000f4287308>] ret_from_fork+0x10/0x20 unreferenced object 0xffffff80cc0b0700 (size 64): comm "kunit_try_catch", pid 1215, jiffies 4294898265 hex dump (first 32 bytes): 80 07 0b cc 80 ff ff ff 28 b7 58 ca 80 ff ff ff ........(.X..... 3c 00 00 00 00 00 00 00 01 2f 03 b3 ec ff ff ff <......../...... backtrace (crc 8d877792): [<0000000052a0be73>] kmemleak_alloc+0x34/0x40 [<0000000043605459>] __kmalloc_cache_noprof+0x26c/0x2f4 [<000000006eadfab7>] vcap_rule_add_action+0x2d0/0x52c [<00000000323475d1>] vcap_api_encode_rule_test+0x4d4/0x16b0 [<00000000b3595fc4>] kunit_try_run_case+0x13c/0x3ac [<0000000010f5d2bf>] kunit_generic_run_threadfn_adapter+0x80/0xec [<00000000c5d82c9a>] kthread+0x2e8/0x374 [<00000000f4287308>] ret_from_fork+0x10/0x20 unreferenced object 0xffffff80cc0b0900 (size 64): comm "kunit_try_catch", pid 1215, jiffies 4294898266 hex dump (first 32 bytes): 80 09 0b cc 80 ff ff ff 80 06 0b cc 80 ff ff ff ................ 7d 00 00 00 01 00 00 00 00 00 00 00 ff 00 00 00 }............... backtrace (crc 34181e56): [<0000000052a0be73>] kmemleak_alloc+0x34/0x40 [<0000000043605459>] __kmalloc_cache_noprof+0x26c/0x2f4 [<000000000ff63fd4>] vcap_rule_add_key+0x2cc/0x528 [<00000000991e3564>] vcap_val_rule+0xcf0/0x13e8 [<00000000fc9868e5>] vcap_api_encode_rule_test+0x678/0x16b0 [<00000000b3595fc4>] kunit_try_run_case+0x13c/0x3ac [<0000000010f5d2bf>] kunit_generic_run_threadfn_adapter+0x80/0xec [<00000000c5d82c9a>] kthread+0x2e8/0x374 [<00000000f4287308>] ret_from_fork+0x10/0x20 unreferenced object 0xffffff80cc0b0980 (size 64): comm "kunit_try_catch", pid 1215, jiffies 4294898266 hex dump (first 32 bytes): 18 b7 58 ca 80 ff ff ff 00 09 0b cc 80 ff ff ff ..X............. 67 00 00 00 00 00 00 00 01 01 74 88 c0 ff ff ff g.........t..... backtrace (crc 275fd9be): [<0000000052a0be73>] kmemleak_alloc+0x34/0x40 [<0000000043605459>] __kmalloc_cache_noprof+0x26c/0x2f4 [<000000000ff63fd4>] vcap_rule_add_key+0x2cc/0x528 [<000000001396a1a2>] test_add_de ---truncated---

In the Linux kernel, the following vulnerability has been resolved: thermal: core: Free tzp copy along with the thermal zone The object pointed to by tz->tzp may still be accessed after being freed in thermal_zone_device_unregister(), so move the freeing of it to the point after the removal completion has been completed at which it cannot be accessed any more.

In the Linux kernel, the following vulnerability has been resolved: drm/xe: Don't free job in TDR Freeing job in TDR is not safe as TDR can pass the run_job thread resulting in UAF. It is only safe for free job to naturally be called by the scheduler. Rather free job in TDR, add to pending list. (cherry picked from commit ea2f6a77d0c40d97f4a4dc93fee4afe15d94926d)

In the Linux kernel, the following vulnerability has been resolved: ksmbd: add refcnt to ksmbd_conn struct When sending an oplock break request, opinfo->conn is used, But freed ->conn can be used on multichannel. This patch add a reference count to the ksmbd_conn struct so that it can be freed when it is no longer used.

In the Linux kernel, the following vulnerability has been resolved: net/ncsi: Disable the ncsi work before freeing the associated structure The work function can run after the ncsi device is freed, resulting in use-after-free bugs or kernel panic.

In the Linux kernel, the following vulnerability has been resolved: crypto: iaa - Fix potential use after free bug The free_device_compression_mode(iaa_device, device_mode) function frees "device_mode" but it iss passed to iaa_compression_modes[i]->free() a few lines later resulting in a use after free. The good news is that, so far as I can tell, nothing implements the ->free() function and the use after free happens in dead code. But, with this fix, when something does implement it, we'll be ready. :)

In the Linux kernel, the following vulnerability has been resolved: xen: privcmd: Fix possible access to a freed kirqfd instance Nothing prevents simultaneous ioctl calls to privcmd_irqfd_assign() and privcmd_irqfd_deassign(). If that happens, it is possible that a kirqfd created and added to the irqfds_list by privcmd_irqfd_assign() may get removed by another thread executing privcmd_irqfd_deassign(), while the former is still using it after dropping the locks. This can lead to a situation where an already freed kirqfd instance may be accessed and cause kernel oops. Use SRCU locking to prevent the same, as is done for the KVM implementation for irqfds.

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Handle mailbox timeouts in lpfc_get_sfp_info The MBX_TIMEOUT return code is not handled in lpfc_get_sfp_info and the routine unconditionally frees submitted mailbox commands regardless of return status. The issue is that for MBX_TIMEOUT cases, when firmware returns SFP information at a later time, that same mailbox memory region references previously freed memory in its cmpl routine. Fix by adding checks for the MBX_TIMEOUT return code. During mailbox resource cleanup, check the mbox flag to make sure that the wait did not timeout. If the MBOX_WAKE flag is not set, then do not free the resources because it will be freed when firmware completes the mailbox at a later time in its cmpl routine. Also, increase the timeout from 30 to 60 seconds to accommodate boot scripts requiring longer timeouts.

In the Linux kernel, the following vulnerability has been resolved: kcm: Serialise kcm_sendmsg() for the same socket. syzkaller reported UAF in kcm_release(). [0] The scenario is 1. Thread A builds a skb with MSG_MORE and sets kcm->seq_skb. 2. Thread A resumes building skb from kcm->seq_skb but is blocked by sk_stream_wait_memory() 3. Thread B calls sendmsg() concurrently, finishes building kcm->seq_skb and puts the skb to the write queue 4. Thread A faces an error and finally frees skb that is already in the write queue 5. kcm_release() does double-free the skb in the write queue When a thread is building a MSG_MORE skb, another thread must not touch it. Let's add a per-sk mutex and serialise kcm_sendmsg(). [0]: BUG: KASAN: slab-use-after-free in __skb_unlink include/linux/skbuff.h:2366 [inline] BUG: KASAN: slab-use-after-free in __skb_dequeue include/linux/skbuff.h:2385 [inline] BUG: KASAN: slab-use-after-free in __skb_queue_purge_reason include/linux/skbuff.h:3175 [inline] BUG: KASAN: slab-use-after-free in __skb_queue_purge include/linux/skbuff.h:3181 [inline] BUG: KASAN: slab-use-after-free in kcm_release+0x170/0x4c8 net/kcm/kcmsock.c:1691 Read of size 8 at addr ffff0000ced0fc80 by task syz-executor329/6167 CPU: 1 PID: 6167 Comm: syz-executor329 Tainted: G B 6.8.0-rc5-syzkaller-g9abbc24128bc #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:291 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:298 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:377 [inline] print_report+0x178/0x518 mm/kasan/report.c:488 kasan_report+0xd8/0x138 mm/kasan/report.c:601 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381 __skb_unlink include/linux/skbuff.h:2366 [inline] __skb_dequeue include/linux/skbuff.h:2385 [inline] __skb_queue_purge_reason include/linux/skbuff.h:3175 [inline] __skb_queue_purge include/linux/skbuff.h:3181 [inline] kcm_release+0x170/0x4c8 net/kcm/kcmsock.c:1691 __sock_release net/socket.c:659 [inline] sock_close+0xa4/0x1e8 net/socket.c:1421 __fput+0x30c/0x738 fs/file_table.c:376 ____fput+0x20/0x30 fs/file_table.c:404 task_work_run+0x230/0x2e0 kernel/task_work.c:180 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0x618/0x1f64 kernel/exit.c:871 do_group_exit+0x194/0x22c kernel/exit.c:1020 get_signal+0x1500/0x15ec kernel/signal.c:2893 do_signal+0x23c/0x3b44 arch/arm64/kernel/signal.c:1249 do_notify_resume+0x74/0x1f4 arch/arm64/kernel/entry-common.c:148 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline] el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:713 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598 Allocated by task 6166: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:68 kasan_save_alloc_info+0x70/0x84 mm/kasan/generic.c:626 unpoison_slab_object mm/kasan/common.c:314 [inline] __kasan_slab_alloc+0x74/0x8c mm/kasan/common.c:340 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook mm/slub.c:3813 [inline] slab_alloc_node mm/slub.c:3860 [inline] kmem_cache_alloc_node+0x204/0x4c0 mm/slub.c:3903 __alloc_skb+0x19c/0x3d8 net/core/skbuff.c:641 alloc_skb include/linux/skbuff.h:1296 [inline] kcm_sendmsg+0x1d3c/0x2124 net/kcm/kcmsock.c:783 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] sock_sendmsg+0x220/0x2c0 net/socket.c:768 splice_to_socket+0x7cc/0xd58 fs/splice.c:889 do_splice_from fs/splice.c:941 [inline] direct_splice_actor+0xec/0x1d8 fs/splice.c:1164 splice_direct_to_actor+0x438/0xa0c fs/splice.c:1108 do_splice_direct_actor ---truncated---

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: Fix possible deadlock in rfcomm_sk_state_change syzbot reports a possible deadlock in rfcomm_sk_state_change [1]. While rfcomm_sock_connect acquires the sk lock and waits for the rfcomm lock, rfcomm_sock_release could have the rfcomm lock and hit a deadlock for acquiring the sk lock. Here's a simplified flow: rfcomm_sock_connect: lock_sock(sk) rfcomm_dlc_open: rfcomm_lock() rfcomm_sock_release: rfcomm_sock_shutdown: rfcomm_lock() __rfcomm_dlc_close: rfcomm_k_state_change: lock_sock(sk) This patch drops the sk lock before calling rfcomm_dlc_open to avoid the possible deadlock and holds sk's reference count to prevent use-after-free after rfcomm_dlc_open completes.

In the Linux kernel, the following vulnerability has been resolved: cgroup/cpuset: Prevent UAF in proc_cpuset_show() An UAF can happen when /proc/cpuset is read as reported in [1]. This can be reproduced by the following methods: 1.add an mdelay(1000) before acquiring the cgroup_lock In the cgroup_path_ns function. 2.$cat /proc/<pid>/cpuset repeatly. 3.$mount -t cgroup -o cpuset cpuset /sys/fs/cgroup/cpuset/ $umount /sys/fs/cgroup/cpuset/ repeatly. The race that cause this bug can be shown as below: (umount) | (cat /proc/<pid>/cpuset) css_release | proc_cpuset_show css_release_work_fn | css = task_get_css(tsk, cpuset_cgrp_id); css_free_rwork_fn | cgroup_path_ns(css->cgroup, ...); cgroup_destroy_root | mutex_lock(&cgroup_mutex); rebind_subsystems | cgroup_free_root | | // cgrp was freed, UAF | cgroup_path_ns_locked(cgrp,..); When the cpuset is initialized, the root node top_cpuset.css.cgrp will point to &cgrp_dfl_root.cgrp. In cgroup v1, the mount operation will allocate cgroup_root, and top_cpuset.css.cgrp will point to the allocated &cgroup_root.cgrp. When the umount operation is executed, top_cpuset.css.cgrp will be rebound to &cgrp_dfl_root.cgrp. The problem is that when rebinding to cgrp_dfl_root, there are cases where the cgroup_root allocated by setting up the root for cgroup v1 is cached. This could lead to a Use-After-Free (UAF) if it is subsequently freed. The descendant cgroups of cgroup v1 can only be freed after the css is released. However, the css of the root will never be released, yet the cgroup_root should be freed when it is unmounted. This means that obtaining a reference to the css of the root does not guarantee that css.cgrp->root will not be freed. Fix this problem by using rcu_read_lock in proc_cpuset_show(). As cgroup_root is kfree_rcu after commit d23b5c577715 ("cgroup: Make operations on the cgroup root_list RCU safe"), css->cgroup won't be freed during the critical section. To call cgroup_path_ns_locked, css_set_lock is needed, so it is safe to replace task_get_css with task_css. [1] https://syzkaller.appspot.com/bug?extid=9b1ff7be974a403aa4cd

A use after free flaw was found in hfsplus_put_super in fs/hfsplus/super.c in the Linux Kernel. This flaw could allow a local user to cause a denial of service problem.

In the Linux kernel, the following vulnerability has been resolved: x86/mm, kexec, ima: Use memblock_free_late() from ima_free_kexec_buffer() The code calling ima_free_kexec_buffer() runs long after the memblock allocator has already been torn down, potentially resulting in a use after free in memblock_isolate_range(). With KASAN or KFENCE, this use after free will result in a BUG from the idle task, and a subsequent kernel panic. Switch ima_free_kexec_buffer() over to memblock_free_late() to avoid that bug.

Use after free in some Intel(R) Aptio* V UEFI Firmware Integrator Tools may allowed an authenticated user to potentially enable denial of service via local access.

A vulnerability was found in the Linux kernel, where accessing a deallocated instance in printer_ioctl() printer_ioctl() tries to access of a printer_dev instance. However, use-after-free arises because it had been freed by gprinter_free().

A NULL pointer dereference flaw was found in the Linux kernel’s X.25 set of standardized network protocols functionality in the way a user terminates their session using a simulated Ethernet card and continued usage of this connection. This flaw allows a local user to crash the system.

A use-after-free vulnerability was found in the cyttsp4_core driver in the Linux kernel. This issue occurs in the device cleanup routine due to a possible rearming of the watchdog_timer from the workqueue. This could allow a local user to crash the system, causing a denial of service.

A use-after-free vulnerabilitity was discovered in drivers/net/hamradio/6pack.c of linux that allows an attacker to crash linux kernel by simulating ax25 device using 6pack driver from user space.