Use After Free Affecting kernel-default-base package, versions <5.3.18-150200.24.209.1.150200.9.109.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-SLES152-KERNELDEFAULTBASE-8444249
- published29 Nov 2024
- disclosed28 Nov 2024
Introduced: 28 Nov 2024
NewCVE-2024-49867 (opens in a new tab)How to fix?
Upgrade SLES:15.2 kernel-default-base to version 5.3.18-150200.24.209.1.150200.9.109.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-default-base package and not the kernel-default-base package as distributed by SLES.
See How to fix? for SLES:15.2 relevant fixed versions and status.
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:
Park the cleaner kthread - this doesn't destroy the kthread, it basically halts its execution (wake ups against it work but do nothing);
We stop the cleaner kthread - this results in freeing the respective struct task_struct;
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---
References
- https://www.suse.com/security/cve/CVE-2024-49867.html
- https://bugzilla.suse.com/1232262
- https://bugzilla.suse.com/1232271
- https://git.kernel.org/stable/c/41fd1e94066a815a7ab0a7025359e9b40e4b3576
- https://git.kernel.org/stable/c/4c98fe0dfa2ae83c4631699695506d8941db4bfe
- https://git.kernel.org/stable/c/65d11eb276836d49003a8060cf31fa2284ad1047
- https://git.kernel.org/stable/c/70b60c8d9b42763d6629e44f448aa5d8ae477d61
- https://git.kernel.org/stable/c/9da40aea63f8769f28afb91aea0fac4cf6fbbb65
- https://git.kernel.org/stable/c/bf0de0f9a0544c11f96f93206da04ab87dcea1f4
- https://git.kernel.org/stable/c/ed87190e9d9c80aad220fb6b0b03a84d22e2c95b
- https://git.kernel.org/stable/c/a71349b692ab34ea197949e13e3cc42570fe73d9
- https://git.kernel.org/stable/c/cd686dfff63f27d712877aef5b962fbf6b8bc264