🛡️ AZL-50874 — kernel (CVE-2024-47689)

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

CVE-2024-47689 affecting package kernel for versions less than 6.6.56.1-5

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to don't set SB_RDONLY in f2fs_handle_critical_error()

syzbot reports a f2fs bug as below:

------------[ cut here ]------------

WARNING: CPU: 1 PID: 58 at kernel/rcu/sync.c:177 rcu_sync_dtor+0xcd/0x180 kernel/rcu/sync.c:177

CPU: 1 UID: 0 PID: 58 Comm: kworker/1:2 Not tainted 6.10.0-syzkaller-12562-g1722389b0d86 #0

Workqueue: events destroy_super_work

RIP: 0010:rcu_sync_dtor+0xcd/0x180 kernel/rcu/sync.c:177

Call Trace:

percpu_free_rwsem+0x41/0x80 kernel/locking/percpu-rwsem.c:42

destroy_super_work+0xec/0x130 fs/super.c:282

process_one_work kernel/workqueue.c:3231 [inline]

process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312

worker_thread+0x86d/0xd40 kernel/workqueue.c:3390

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

As Christian Brauner pointed out [1]: the root cause is f2fs sets

SB_RDONLY flag in internal function, rather than setting the flag

covered w/ sb->s_umount semaphore via remount procedure, then below

race condition causes this bug:

  • freeze_super()
  • sb_wait_write(sb, SB_FREEZE_WRITE)
  • sb_wait_write(sb, SB_FREEZE_PAGEFAULT)
  • sb_wait_write(sb, SB_FREEZE_FS)
  • f2fs_handle_critical_error
  • sb->s_flags |= SB_RDONLY
  • thaw_super
  • thaw_super_locked
  • sb_rdonly() is true, so it skips

sb_freeze_unlock(sb, SB_FREEZE_FS)

  • deactivate_locked_super

Since f2fs has almost the same logic as ext4 [2] when handling critical

error in filesystem if it mounts w/ errors=remount-ro option:

  • set CP_ERROR_FLAG flag which indicates filesystem is stopped
  • record errors to superblock
  • set SB_RDONLY falg

Once we set CP_ERROR_FLAG flag, all writable interfaces can detect the

flag and stop any further updates on filesystem. So, it is safe to not

set SB_RDONLY flag, let's remove the logic and keep in line w/ ext4 [3].

[1] https://lore.kernel.org/all/20240729-himbeeren-funknetz-96e62f9c7aee@brauner

[2] https://lore.kernel.org/all/20240729132721.hxih6ehigadqf7wx@quack3

[3] https://lore.kernel.org/linux-ext4/[email protected]

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software

AZL-50874 is recorded against 1 package.

  • kernel (fixed in 6.6.56.1-5)

Timeline and source

Published on 21 October 2024 and last revised on 21 April 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

nvd.nist.gov (Web)

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2024-10-21
Updated 2026-08-12
Modified 2026-04-21
Fix URL N/A

Affected Packages

Software From version Fixed in
kernel — 6.6.56.1-5

Similar Threats

Free Vulnerability Check

Is your site affected by AZL-50874?

BotEraser helps you identify potentially vulnerable plugins and themes by checking your installation against AZL-50874 and other known CVE records.

Scan My Site Free →

No credit card required  ·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

Browse related advisories

All advisoriesAzure LinuxAzure Linux Undated