{"id":"CVE-2025-40138","state":"PUBLISHED","title":"f2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency()\n\nsyzbot reported a f2fs bug as below:\n\nOops: gen[  107.736417][ T5848] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI\nKASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\nCPU: 1 UID: 0 PID: 5848 Comm: syz-executor263 Tainted: G        W           6.17.0-rc1-syzkaller-00014-g0e39a731820a #0 PREEMPT_{RT,(full)}\nRIP: 0010:strcmp+0x3c/0xc0 lib/string.c:284\nCall Trace:\n <TASK>\n f2fs_check_quota_consistency fs/f2fs/super.c:1188 [inline]\n f2fs_check_opt_consistency+0x1378/0x2c10 fs/f2fs/super.c:1436\n __f2fs_remount fs/f2fs/super.c:2653 [inline]\n f2fs_reconfigure+0x482/0x1770 fs/f2fs/super.c:5297\n reconfigure_super+0x224/0x890 fs/super.c:1077\n do_remount fs/namespace.c:3314 [inline]\n path_mount+0xd18/0xfe0 fs/namespace.c:4112\n do_mount fs/namespace.c:4133 [inline]\n __do_sys_mount fs/namespace.c:4344 [inline]\n __se_sys_mount+0x317/0x410 fs/namespace.c:4321\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nThe direct reason is f2fs_check_quota_consistency() may suffer null-ptr-deref\nissue in strcmp().\n\nThe bug can be reproduced w/ below scripts:\nmkfs.f2fs -f /dev/vdb\nmount -t f2fs -o usrquota /dev/vdb /mnt/f2fs\nquotacheck -uc /mnt/f2fs/\numount /mnt/f2fs\nmount -t f2fs -o usrjquota=aquota.user,jqfmt=vfsold /dev/vdb /mnt/f2fs\nmount -t f2fs -o remount,usrjquota=,jqfmt=vfsold /dev/vdb /mnt/f2fs\numount /mnt/f2fs\n\nSo, before old_qname and new_qname comparison, we need to check whether\nthey are all valid pointers, fix it.","publishedAt":"2025-11-12T10:23:23.912Z","updatedAt":"2026-05-11T21:43:29.612Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d185351325237da688de006a2c579e82ea97bdfe","status":"affected","lessThan":"3f3458852bbfe79c60f2412b8b04677b96688b6e","versionType":"git"},{"version":"d185351325237da688de006a2c579e82ea97bdfe","status":"affected","lessThan":"930a9a6ee8e7ffa20af4bffbfc2bbd21d83bf81c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/super.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.17.3","status":"unaffected","lessThanOrEqual":"6.17.*","versionType":"semver"},{"version":"6.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/super.c"]}],"references":["https://git.kernel.org/stable/c/3f3458852bbfe79c60f2412b8b04677b96688b6e","https://git.kernel.org/stable/c/930a9a6ee8e7ffa20af4bffbfc2bbd21d83bf81c"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/40xxx/CVE-2025-40138.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40138","state":"PUBLISHED","datePublished":"2025-11-12T10:23:23.912Z","dateUpdated":"2026-05-11T21:43:29.612Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.171Z"},"containers":{"cna":{"title":"f2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency()\n\nsyzbot reported a f2fs bug as below:\n\nOops: gen[  107.736417][ T5848] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI\nKASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\nCPU: 1 UID: 0 PID: 5848 Comm: syz-executor263 Tainted: G        W           6.17.0-rc1-syzkaller-00014-g0e39a731820a #0 PREEMPT_{RT,(full)}\nRIP: 0010:strcmp+0x3c/0xc0 lib/string.c:284\nCall Trace:\n <TASK>\n f2fs_check_quota_consistency fs/f2fs/super.c:1188 [inline]\n f2fs_check_opt_consistency+0x1378/0x2c10 fs/f2fs/super.c:1436\n __f2fs_remount fs/f2fs/super.c:2653 [inline]\n f2fs_reconfigure+0x482/0x1770 fs/f2fs/super.c:5297\n reconfigure_super+0x224/0x890 fs/super.c:1077\n do_remount fs/namespace.c:3314 [inline]\n path_mount+0xd18/0xfe0 fs/namespace.c:4112\n do_mount fs/namespace.c:4133 [inline]\n __do_sys_mount fs/namespace.c:4344 [inline]\n __se_sys_mount+0x317/0x410 fs/namespace.c:4321\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nThe direct reason is f2fs_check_quota_consistency() may suffer null-ptr-deref\nissue in strcmp().\n\nThe bug can be reproduced w/ below scripts:\nmkfs.f2fs -f /dev/vdb\nmount -t f2fs -o usrquota /dev/vdb /mnt/f2fs\nquotacheck -uc /mnt/f2fs/\numount /mnt/f2fs\nmount -t f2fs -o usrjquota=aquota.user,jqfmt=vfsold /dev/vdb /mnt/f2fs\nmount -t f2fs -o remount,usrjquota=,jqfmt=vfsold /dev/vdb /mnt/f2fs\numount /mnt/f2fs\n\nSo, before old_qname and new_qname comparison, we need to check whether\nthey are all valid pointers, fix it."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d185351325237da688de006a2c579e82ea97bdfe","status":"affected","lessThan":"3f3458852bbfe79c60f2412b8b04677b96688b6e","versionType":"git"},{"version":"d185351325237da688de006a2c579e82ea97bdfe","status":"affected","lessThan":"930a9a6ee8e7ffa20af4bffbfc2bbd21d83bf81c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/super.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.17.3","status":"unaffected","lessThanOrEqual":"6.17.*","versionType":"semver"},{"version":"6.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/super.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/3f3458852bbfe79c60f2412b8b04677b96688b6e"},{"url":"https://git.kernel.org/stable/c/930a9a6ee8e7ffa20af4bffbfc2bbd21d83bf81c"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T21:43:29.612Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.17.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.18"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}