f2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-40138
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-11-12 11:15:43 UTC
Updated2026-10-19 21:10:00 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency() syzbot reported a f2fs bug as below: Oops: gen[ 107.736417][ T5848] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 UID: 0 PID: 5848 Comm: syz-executor263 Tainted: G W 6.17.0-rc1-syzkaller-00014-g0e39a731820a #0 PREEMPT_{RT,(full)} RIP: 0010:strcmp+0x3c/0xc0 lib/string.c:284 Call Trace: <TASK> f2fs_check_quota_consistency fs/f2fs/super.c:1188 [inline] f2fs_check_opt_consistency+0x1378/0x2c10 fs/f2fs/super.c:1436 __f2fs_remount fs/f2fs/super.c:2653 [inline] f2fs_reconfigure+0x482/0x1770 fs/f2fs/super.c:5297 reconfigure_super+0x224/0x890 fs/super.c:1077 do_remount fs/namespace.c:3314 [inline] path_mount+0xd18/0xfe0 fs/namespace.c:4112 do_mount fs/namespace.c:4133 [inline] __do_sys_mount fs/namespace.c:4344 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4321 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The direct reason is f2fs_check_quota_consistency() may suffer null-ptr-deref issue in strcmp(). The bug can be reproduced w/ below scripts: mkfs.f2fs -f /dev/vdb mount -t f2fs -o usrquota /dev/vdb /mnt/f2fs quotacheck -uc /mnt/f2fs/ umount /mnt/f2fs mount -t f2fs -o usrjquota=aquota.user,jqfmt=vfsold /dev/vdb /mnt/f2fs mount -t f2fs -o remount,usrjquota=,jqfmt=vfsold /dev/vdb /mnt/f2fs umount /mnt/f2fs So, before old_qname and new_qname comparison, we need to check whether they are all valid pointers, fix it.

Risk And Classification

EPSS: 0.001980000 probability, percentile 0.090220000 (date 2026-10-19)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d185351325237da688de006a2c579e82ea97bdfe 3f3458852bbfe79c60f2412b8b04677b96688b6e git Not specified
CNA Linux Linux affected d185351325237da688de006a2c579e82ea97bdfe 930a9a6ee8e7ffa20af4bffbfc2bbd21d83bf81c git Not specified
CNA Linux Linux affected 6.17 Not specified
CNA Linux Linux unaffected 6.17 semver Not specified
CNA Linux Linux unaffected 6.17.3 6.17.* semver Not specified
CNA Linux Linux unaffected 6.18 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/3f3458852bbfe79c60f2412b8b04677b96688b6e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/930a9a6ee8e7ffa20af4bffbfc2bbd21d83bf81c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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