---
id: CVE-2024-49903
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  jfs: Fix uaf in dbFreeBits

  [syzbot reported]
  ==================================================================
  BUG: KASAN: slab-use-after-free in __mutex_lock_common …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  jfs: Fix uaf in dbFreeBits

  [syzbot reported]
  ==================================================================
  BUG: KASAN: slab-use-after-free in __mutex_lock_common …
severity: high
cvss: 7
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - linux_kernel < 5.10.227
  - 'linux_kernel >= 5.11, < 5.15.168'
  - 'linux_kernel >= 5.16, < 6.1.113'
  - 'linux_kernel >= 6.2, < 6.6.55'
  - 'linux_kernel >= 6.7, < 6.10.14'
  - 'linux_kernel >= 6.11, < 6.11.3'
patched:
  - linux_kernel 6.11.3
published: '2024-10-21'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T01:19:00.923'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2024-49903'
references:
  - url: 'https://git.kernel.org/stable/c/0c238da83f56bb895cab1e5851d034ac45b158d1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3126ccde51f51b0648c8cdccaf916e8bd062e972'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4218b31ecc7af7e191768d32e32ed4386d8f9b76'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4ac58f7734937f3249da734ede946dfb3b1af5e4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/95accb7183badca387f7a8d19a2475cf3089f148'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a9603a6f75df2fd8125cd208c98cfaa0fe3f7505'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d6c1b3599b2feb5c7291f5ac3a36e5fa7cedb234'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e7ae14f7ee76c6ef5a48aebab1a278ad78f42619'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fd026b6b6758d5569705c02540b40f3bbf822b9a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-265688.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-355557.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00255
epssPercentile: 0.16964
ingestedAt: '2026-10-15T03:30:12.753Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2024-10-22T13:42:37.771677Z'
---

## Overview

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

jfs: Fix uaf in dbFreeBits

[syzbot reported]
==================================================================
BUG: KASAN: slab-use-after-free in __mutex_lock_common kernel/locking/mutex.c:587 [inline]
BUG: KASAN: slab-use-after-free in __mutex_lock+0xfe/0xd70 kernel/locking/mutex.c:752
Read of size 8 at addr ffff8880229254b0 by task syz-executor357/5216

CPU: 0 UID: 0 PID: 5216 Comm: syz-executor357 Not tainted 6.11.0-rc3-syzkaller-00156-gd7a5aa4b3c00 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 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
 __mutex_lock_common kernel/locking/mutex.c:587 [inline]
 __mutex_lock+0xfe/0xd70 kernel/locking/mutex.c:752
 dbFreeBits+0x7ea/0xd90 fs/jfs/jfs_dmap.c:2390
 dbFreeDmap fs/jfs/jfs_dmap.c:2089 [inline]
 dbFree+0x35b/0x680 fs/jfs/jfs_dmap.c:409
 dbDiscardAG+0x8a9/0xa20 fs/jfs/jfs_dmap.c:1650
 jfs_ioc_trim+0x433/0x670 fs/jfs/jfs_discard.c:100
 jfs_ioctl+0x2d0/0x3e0 fs/jfs/ioctl.c:131
 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

Freed by task 5218:
 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+0xe0/0x150 mm/kasan/common.c:240
 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2252 [inline]
 slab_free mm/slub.c:4473 [inline]
 kfree+0x149/0x360 mm/slub.c:4594
 dbUnmount+0x11d/0x190 fs/jfs/jfs_dmap.c:278
 jfs_mount_rw+0x4ac/0x6a0 fs/jfs/jfs_mount.c:247
 jfs_remount+0x3d1/0x6b0 fs/jfs/super.c:454
 reconfigure_super+0x445/0x880 fs/super.c:1083
 vfs_cmd_reconfigure fs/fsopen.c:263 [inline]
 vfs_fsconfig_locked fs/fsopen.c:292 [inline]
 __do_sys_fsconfig fs/fsopen.c:473 [inline]
 __se_sys_fsconfig+0xb6e/0xf80 fs/fsopen.c:345
 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

[Analysis]
There are two paths (dbUnmount and jfs_ioc_trim) that generate race
condition when accessing bmap, which leads to the occurrence of uaf.

Use the lock s_umount to synchronize them, in order to avoid uaf caused
by race condition.

## Affected

- `linux_kernel < 5.10.227`
- `linux_kernel >= 5.11, < 5.15.168`
- `linux_kernel >= 5.16, < 6.1.113`
- `linux_kernel >= 6.2, < 6.6.55`
- `linux_kernel >= 6.7, < 6.10.14`
- `linux_kernel >= 6.11, < 6.11.3`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.11.3`