{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-40943", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-07-12T12:17:45.588Z", "datePublished": "2024-07-12T12:25:17.813Z", "dateUpdated": "2026-08-05T11:34:09.554Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:34:09.554Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix races between hole punching and AIO+DIO\n\nAfter commit \"ocfs2: return real error code in ocfs2_dio_wr_get_block\",\nfstests/generic/300 become from always failed to sometimes failed:\n\n========================================================================\n[ 473.293420 ] run fstests generic/300\n\n[ 475.296983 ] JBD2: Ignoring recovery information on journal\n[ 475.302473 ] ocfs2: Mounting device (253,1) on (node local, slot 0) with ordered data mode.\n[ 494.290998 ] OCFS2: ERROR (device dm-1): ocfs2_change_extent_flag: Owner 5668 has an extent at cpos 78723 which can no longer be found\n[ 494.291609 ] On-disk corruption discovered. Please run fsck.ocfs2 once the filesystem is unmounted.\n[ 494.292018 ] OCFS2: File system is now read-only.\n[ 494.292224 ] (kworker/19:11,2628,19):ocfs2_mark_extent_written:5272 ERROR: status = -30\n[ 494.292602 ] (kworker/19:11,2628,19):ocfs2_dio_end_io_write:2374 ERROR: status = -3\nfio: io_u error on file /mnt/scratch/racer: Read-only file system: write offset=460849152, buflen=131072\n=========================================================================\n\nIn __blockdev_direct_IO, ocfs2_dio_wr_get_block is called to add unwritten\nextents to a list. extents are also inserted into extent tree in\nocfs2_write_begin_nolock. Then another thread call fallocate to puch a\nhole at one of the unwritten extent. The extent at cpos was removed by\nocfs2_remove_extent(). At end io worker thread, ocfs2_search_extent_list\nfound there is no such extent at the cpos.\n\n T1 T2 T3\n inode lock\n ...\n insert extents\n ...\n inode unlock\nocfs2_fallocate\n __ocfs2_change_file_space\n inode lock\n lock ip_alloc_sem\n ocfs2_remove_inode_range inode\n ocfs2_remove_btree_range\n ocfs2_remove_extent\n ^---remove the extent at cpos 78723\n ...\n unlock ip_alloc_sem\n inode unlock\n ocfs2_dio_end_io\n ocfs2_dio_end_io_write\n lock ip_alloc_sem\n ocfs2_mark_extent_written\n ocfs2_change_extent_flag\n ocfs2_search_extent_list\n ^---failed to find extent\n ...\n unlock ip_alloc_sem\n\nIn most filesystems, fallocate is not compatible with racing with AIO+DIO,\nso fix it by adding to wait for all dio before fallocate/punch_hole like\next4." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The race is driven entirely by local syscalls — `io_submit()`/`io_uring` O_DIRECT writes reaching `ocfs2_dio_wr_get_block()` and `fallocate(FALLOC_FL_PUNCH_HOLE)`/`OCFS2_IOC_UNRESVSP` reaching `__ocfs2_change_file_space()` on an already-mounted ocfs2 volume. No remote peer or packet data reaches the vulnerable path; ocfs2 is a shared-disk cluster filesystem, not a network server.\nAC:L - The attacker owns both sides of the race: one thread issues async O_DIRECT writes that return `-EIOCBQUEUED` and defer `ocfs2_dio_end_io_write()`, while another calls `fallocate(PUNCH_HOLE)` over the same range, and the sequence can be looped indefinitely at no cost until it lands. Nothing depends on state outside the attacker's influence — the `unwritten` feature bit required by `ocfs2_fallocate()` is the mkfs.ocfs2 default, and the upstream reproducer (fstests generic/300) hits it with an ordinary fio racer workload.\nPR:L - Only an unprivileged local account with write access to a file on the ocfs2 volume is needed — `ocfs2_fallocate()` has no capability check and `ocfs2_change_file_space()` gates solely on `S_ISREG` plus `FMODE_WRITE` on the caller's own fd. No CAP_SYS_ADMIN, no user-namespace trick, and no root is required, since the attacker races only on a file it already owns.\nUI:N - The attacker performs the whole sequence from its own processes with no action by any other user. The ocfs2 volume is already mounted in the normal deployment (a cluster shared-storage node), so no victim mount or file open is involved.\nS:U - The corrupted extent tree, the freed-then-rewritten clusters, and the forced-read-only superblock all live within the kernel's own security authority. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - `ocfs2_change_extent_flag()` builds `split_rec.e_blkno` from the stale `ue_phys` captured before the punch and never validates it against the record it found (`fs/ocfs2/alloc.c:5232`), so once a re-write repopulates an unwritten extent at that `cpos` the split installs a mapping to clusters that `ocfs2_truncate_log_append()` already released to the global bitmap and handed to another inode. The attacker's file then aliases another user's data blocks — an arbitrary read of other users' file contents across every node of the cluster — and with `errors=continue` the volume keeps serving that inconsistent metadata.\nI:H - The punch frees the clusters into the truncate log and flushes them for reuse while the DIO's data BIOs are still in flight to those exact physical blocks, so attacker-controlled bytes overwrite whatever inode was subsequently allocated them, and the stale-`e_blkno` split additionally grants a persistent write alias into another user's file. The result is on-disk corruption that the kernel itself reports as requiring offline `fsck.ocfs2` to repair.\nA:H - `ocfs2_change_extent_flag()` calls `ocfs2_error()`, and `ocfs2_handle_error()` (`fs/ocfs2/super.c:2482`) either calls `panic()` under the cluster-typical `errors=panic` or, by default, sets `SB_RDONLY` and prints \"File system is now read-only\" — an unprivileged user can thus take the entire shared volume offline for every process on the node. Recovery requires unmounting cluster-wide and running fsck, and the trigger can be repeated at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ocfs2/file.c" ], "versions": [ { "version": "b25801038da5823bba1b5440a57ca68afc51b6bd", "lessThan": "3c26b5d21b1239e9c7fd31ba7d9b2d7bdbaa68d9", "status": "affected", "versionType": "git" }, { "version": "b25801038da5823bba1b5440a57ca68afc51b6bd", "lessThan": "e8e2db1adac47970a6a9225f3858e9aa0e86287f", "status": "affected", "versionType": "git" }, { "version": "b25801038da5823bba1b5440a57ca68afc51b6bd", "lessThan": "050ce8af6838c71e872e982b50d3f1bec21da40e", "status": "affected", "versionType": "git" }, { "version": "b25801038da5823bba1b5440a57ca68afc51b6bd", "lessThan": "38825ff9da91d2854dcf6d9ac320a7e641e10f25", "status": "affected", "versionType": "git" }, { "version": "b25801038da5823bba1b5440a57ca68afc51b6bd", "lessThan": "ea042dc2bea19d72e37c298bf65a9c341ef3fff3", "status": "affected", "versionType": "git" }, { "version": "b25801038da5823bba1b5440a57ca68afc51b6bd", "lessThan": "3c361f313d696df72f9bccf058510e9ec737b9b1", "status": "affected", "versionType": "git" }, { "version": "b25801038da5823bba1b5440a57ca68afc51b6bd", "lessThan": "117b9c009b72a6c2ebfd23484354dfee2d9570d2", "status": "affected", "versionType": "git" }, { "version": "b25801038da5823bba1b5440a57ca68afc51b6bd", "lessThan": "952b023f06a24b2ad6ba67304c4c84d45bea2f18", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ocfs2/file.c" ], "versions": [ { "version": "2.6.23", "status": "affected" }, { "version": "0", "lessThan": "2.6.23", "status": "unaffected", "versionType": "semver" }, { "version": "4.19.317", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.279", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.221", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.162", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.95", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.35", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.6", "lessThanOrEqual": "6.9.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.23", "versionEndExcluding": "4.19.317" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.23", "versionEndExcluding": "5.4.279" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.23", "versionEndExcluding": "5.10.221" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.23", "versionEndExcluding": "5.15.162" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.23", "versionEndExcluding": "6.1.95" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.23", "versionEndExcluding": "6.6.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.23", "versionEndExcluding": "6.9.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.23", "versionEndExcluding": "6.10" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3c26b5d21b1239e9c7fd31ba7d9b2d7bdbaa68d9" }, { "url": "https://git.kernel.org/stable/c/e8e2db1adac47970a6a9225f3858e9aa0e86287f" }, { "url": "https://git.kernel.org/stable/c/050ce8af6838c71e872e982b50d3f1bec21da40e" }, { "url": "https://git.kernel.org/stable/c/38825ff9da91d2854dcf6d9ac320a7e641e10f25" }, { "url": "https://git.kernel.org/stable/c/ea042dc2bea19d72e37c298bf65a9c341ef3fff3" }, { "url": "https://git.kernel.org/stable/c/3c361f313d696df72f9bccf058510e9ec737b9b1" }, { "url": "https://git.kernel.org/stable/c/117b9c009b72a6c2ebfd23484354dfee2d9570d2" }, { "url": "https://git.kernel.org/stable/c/952b023f06a24b2ad6ba67304c4c84d45bea2f18" } ], "title": "ocfs2: fix races between hole punching and AIO+DIO", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": 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