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VulnerabilityPublished Updated

CVE-2024-47691: Linux kernel · f2fs: fix to avoid use-after-free in f2fs_stop_gc_thread()

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 7.8 High · fixed in 5.4.0-1153.163~18.04.1 : patch Linux kernel soon.

Data as of 12 Nov 2026, 19:06 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 5.4.0-1153.163~18.04.1, 5.4.0-1156.163~18.04.1, 5.4.0-1156.165~18.04.1 +82
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Oct 2024

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-54.56
Fixed in
  • 6.8.0-54.56
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1023.25
Fixed in
  • 6.8.0-1023.25
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1025.30
Fixed in
  • 6.8.0-1025.30
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threatsAffected
  • <6.11.0-1012.12~24.04.1
Fixed in
  • 6.11.0-1012.12~24.04.1
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1014.15
Fixed in
  • 6.8.0-1014.15
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1024.26
Fixed in
  • 6.8.0-1024.26

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid use-after-free in f2fs_stop_gc_thread() syzbot reports a f2fs bug as below: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 print_report+0xe8/0x550 mm/kasan/report.c:491 kasan_report+0x143/0x180 mm/kasan/report.c:601 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189 instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline] __refcount_add include/linux/refcount.h:184 [inline] __refcount_inc include/linux/refcount.h:241 [inline] refcount_inc include/linux/refcount.h:258 [inline] get_task_struct include/linux/sched/task.h:118 [inline] kthread_stop+0xca/0x630 kernel/kthread.c:704 f2fs_stop_gc_thread+0x65/0xb0 fs/f2fs/gc.c:210 f2fs_do_shutdown+0x192/0x540 fs/f2fs/file.c:2283 f2fs_ioc_shutdown fs/f2fs/file.c:2325 [inline] __f2fs_ioctl+0x443a/0xbe60 fs/f2fs/file.c:4325 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f The root cause is below race condition, it may cause use-after-free issue in sbi->gc_th pointer. - remount - f2fs_remount - f2fs_stop_gc_thread - kfree(gc_th) - f2fs_ioc_shutdown - f2fs_do_shutdown - f2fs_stop_gc_thread - kthread_stop(gc_th->f2fs_gc_task) : sbi->gc_thread = NULL; We will call f2fs_do_shutdown() in two paths: - for f2fs_ioc_shutdown() path, we should grab sb->s_umount semaphore for fixing. - for f2fs_shutdown() path, it's safe since caller has already grabbed sb->s_umount semaphore.

References

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