{"id":"CVE-2025-40167","state":"PUBLISHED","title":"ext4: detect invalid INLINE_DATA + EXTENTS flag combination","description":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: detect invalid INLINE_DATA + EXTENTS flag combination\n\nsyzbot reported a BUG_ON in ext4_es_cache_extent() when opening a verity\nfile on a corrupted ext4 filesystem mounted without a journal.\n\nThe issue is that the filesystem has an inode with both the INLINE_DATA\nand EXTENTS flags set:\n\n    EXT4-fs error (device loop0): ext4_cache_extents:545: inode #15:\n    comm syz.0.17: corrupted extent tree: lblk 0 < prev 66\n\nInvestigation revealed that the inode has both flags set:\n    DEBUG: inode 15 - flag=1, i_inline_off=164, has_inline=1, extents_flag=1\n\nThis is an invalid combination since an inode should have either:\n- INLINE_DATA: data stored directly in the inode\n- EXTENTS: data stored in extent-mapped blocks\n\nHaving both flags causes ext4_has_inline_data() to return true, skipping\nextent tree validation in __ext4_iget(). The unvalidated out-of-order\nextents then trigger a BUG_ON in ext4_es_cache_extent() due to integer\nunderflow when calculating hole sizes.\n\nFix this by detecting this invalid flag combination early in ext4_iget()\nand rejecting the corrupted inode.","publishedAt":"2025-11-12T10:26:24.498Z","updatedAt":"2026-10-15T22:02:39.184Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"4954d297c91d292630ab43ba4d195dc371ce65d3","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"f061f7c331fc16250fc82aa68964f35821687217","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"2e9e10657b04152ed0d6ecae8d0c02a3405e28f5","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"1437c95ab2a28b138d4521653583729f61ccb48b","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"cb6039b68efa547b676a8a10fc4618d9d1865c23","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"de985264eef64be8a90595908f2e6a87946dad34","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"1f5ccd22ff482639133f2a0fe08f6d19d0e68717","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"1d3ad183943b38eec2acf72a0ae98e635dc8456b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/inode.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.8","versionType":"semver"},{"version":"5.4.301","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.246","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.196","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.158","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.114","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.55","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.17.5","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/ext4/inode.c"]}],"references":["https://git.kernel.org/stable/c/4954d297c91d292630ab43ba4d195dc371ce65d3","https://git.kernel.org/stable/c/f061f7c331fc16250fc82aa68964f35821687217","https://git.kernel.org/stable/c/2e9e10657b04152ed0d6ecae8d0c02a3405e28f5","https://git.kernel.org/stable/c/1437c95ab2a28b138d4521653583729f61ccb48b","https://git.kernel.org/stable/c/cb6039b68efa547b676a8a10fc4618d9d1865c23","https://git.kernel.org/stable/c/de985264eef64be8a90595908f2e6a87946dad34","https://git.kernel.org/stable/c/1f5ccd22ff482639133f2a0fe08f6d19d0e68717","https://git.kernel.org/stable/c/1d3ad183943b38eec2acf72a0ae98e635dc8456b"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/40xxx/CVE-2025-40167.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40167","state":"PUBLISHED","datePublished":"2025-11-12T10:26:24.498Z","dateUpdated":"2026-10-15T22:02:39.184Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.176Z"},"containers":{"cna":{"title":"ext4: detect invalid INLINE_DATA + EXTENTS flag combination","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: detect invalid INLINE_DATA + EXTENTS flag combination\n\nsyzbot reported a BUG_ON in ext4_es_cache_extent() when opening a verity\nfile on a corrupted ext4 filesystem mounted without a journal.\n\nThe issue is that the filesystem has an inode with both the INLINE_DATA\nand EXTENTS flags set:\n\n    EXT4-fs error (device loop0): ext4_cache_extents:545: inode #15:\n    comm syz.0.17: corrupted extent tree: lblk 0 < prev 66\n\nInvestigation revealed that the inode has both flags set:\n    DEBUG: inode 15 - flag=1, i_inline_off=164, has_inline=1, extents_flag=1\n\nThis is an invalid combination since an inode should have either:\n- INLINE_DATA: data stored directly in the inode\n- EXTENTS: data stored in extent-mapped blocks\n\nHaving both flags causes ext4_has_inline_data() to return true, skipping\nextent tree validation in __ext4_iget(). The unvalidated out-of-order\nextents then trigger a BUG_ON in ext4_es_cache_extent() due to integer\nunderflow when calculating hole sizes.\n\nFix this by detecting this invalid flag combination early in ext4_iget()\nand rejecting the corrupted inode."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"4954d297c91d292630ab43ba4d195dc371ce65d3","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"f061f7c331fc16250fc82aa68964f35821687217","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"2e9e10657b04152ed0d6ecae8d0c02a3405e28f5","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"1437c95ab2a28b138d4521653583729f61ccb48b","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"cb6039b68efa547b676a8a10fc4618d9d1865c23","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"de985264eef64be8a90595908f2e6a87946dad34","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"1f5ccd22ff482639133f2a0fe08f6d19d0e68717","versionType":"git"},{"version":"f19d5870cbf72d4cb2a8e1f749dff97af99b071e","status":"affected","lessThan":"1d3ad183943b38eec2acf72a0ae98e635dc8456b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/inode.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.8","versionType":"semver"},{"version":"5.4.301","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.246","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.196","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.158","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.114","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.55","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.17.5","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/ext4/inode.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4954d297c91d292630ab43ba4d195dc371ce65d3"},{"url":"https://git.kernel.org/stable/c/f061f7c331fc16250fc82aa68964f35821687217"},{"url":"https://git.kernel.org/stable/c/2e9e10657b04152ed0d6ecae8d0c02a3405e28f5"},{"url":"https://git.kernel.org/stable/c/1437c95ab2a28b138d4521653583729f61ccb48b"},{"url":"https://git.kernel.org/stable/c/cb6039b68efa547b676a8a10fc4618d9d1865c23"},{"url":"https://git.kernel.org/stable/c/de985264eef64be8a90595908f2e6a87946dad34"},{"url":"https://git.kernel.org/stable/c/1f5ccd22ff482639133f2a0fe08f6d19d0e68717"},{"url":"https://git.kernel.org/stable/c/1d3ad183943b38eec2acf72a0ae98e635dc8456b"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The invalid flag combination can only be delivered on a crafted ext4 on-disk image attached locally (USB stick, SD card, loop-mounted file), and the bug fires during `ext4_iget()`/`ext4_map_blocks()` on the local mount; there is no network-facing input into this code path.\nAC:L - The attacker fully controls the image and merely sets both INLINE_DATA_FL and EXTENTS_FL on an inode with a `system.data` xattr, formatting without a journal — this deterministically bypasses `ext4_ext_check_inode()` and trips `BUG_ON(end < lblk)` on every open, with no race, timing, or memory-layout condition outside the attacker's control.\nPR:N - The attacker needs no account or privilege on the target — they only supply the malicious filesystem image, and the privileged mount plus the subsequent file access are performed by the victim, an indexer/thumbnailer, or an automounter such as udisks2 or vold.\nUI:R - Because `ext4_fs_type` lacks `FS_USERNS_MOUNT` and `INLINE_DATA_FL` is not in `EXT4_FL_USER_MODIFIABLE`, the corrupt inode cannot be created on a live filesystem; a user or automounter must actually mount the attacker-supplied ext4 image.\nS:U - The out-of-bounds accesses and the panic are confined to the mounting host's kernel memory and its own filesystem, within a single security authority; no VM, hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - Skipping `__ext4_ext_check()` leaves `eh_entries` unvalidated (up to 65535 versus the 4 that fit in the 60-byte `i_block[]`), so `ext4_cache_extents()` and `ext4_ext_binsearch()` read hundreds of kilobytes past the `ext4_inode_info` slab object, and those out-of-bounds kernel bytes are interpreted as physical block numbers that drive real disk reads and are reported back to userspace through FIEMAP.\nI:H - The unvalidated `eh_max` defeats the `eh_entries >= eh_max` guard in `ext4_ext_insert_extent()`, so extent entries are memmoved and written past the end of `i_block[]` into adjacent `ext4_inode_info` slab fields, giving a heap out-of-bounds write; the missing `ext4_valid_extent()`/`ext4_inode_block_valid()` check additionally lets writes and block frees land on superblock, bitmap, and group-descriptor blocks.\nA:H - The out-of-order extents produce an integer underflow in `lblk - prev` and hit `BUG_ON(end < lblk)` in `ext4_es_cache_extent()`, an immediate and reliably reproducible kernel panic on every access to the crafted file; the out-of-bounds slab reads independently oops the kernel on KASAN and hardened builds."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:08:12.384Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.4.301"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.10.246"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.15.196"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.1.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.6.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.12.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.17.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.18"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2025-40167","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-15T21:57:26.297320Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T22:02:39.184Z"}}]}}}