{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-33847", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-06-24T13:54:11.027Z", "datePublished": "2024-06-24T13:56:48.723Z", "dateUpdated": "2026-08-05T11:29:51.830Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:29:51.830Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: compress: don't allow unaligned truncation on released compress inode\n\nf2fs image may be corrupted after below testcase:\n- mkfs.f2fs -O extra_attr,compression -f /dev/vdb\n- mount /dev/vdb /mnt/f2fs\n- touch /mnt/f2fs/file\n- f2fs_io setflags compression /mnt/f2fs/file\n- dd if=/dev/zero of=/mnt/f2fs/file bs=4k count=4\n- f2fs_io release_cblocks /mnt/f2fs/file\n- truncate -s 8192 /mnt/f2fs/file\n- umount /mnt/f2fs\n- fsck.f2fs /dev/vdb\n\n[ASSERT] (fsck_chk_inode_blk:1256) --> ino: 0x5 has i_blocks: 0x00000002, but has 0x3 blocks\n[FSCK] valid_block_count matching with CP [Fail] [0x4, 0x5]\n[FSCK] other corrupted bugs [Fail]\n\nThe reason is: partial truncation assume compressed inode has reserved\nblocks, after partial truncation, valid block count may change w/o\n.i_blocks and .total_valid_block_count update, result in corruption.\n\nThis patch only allow cluster size aligned truncation on released\ncompress inode for fixing." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The entire attack sequence is local syscalls/ioctls on a mounted f2fs volume — `FS_IOC_SETFLAGS`, `write()`, `F2FS_IOC_RELEASE_COMPRESS_BLOCKS`, then `truncate()`. There is no network or remote-peer component.\nAC:L - The commit message contains a straight-line shell reproducer with no race, timing window, or memory-layout dependency; the attacker deterministically drives every step. f2fs compression is a standard, widely deployed configuration (Android /data, embedded flash devices).\nPR:L - `f2fs_release_compress_blocks()` carries no capability check at all — only `mnt_want_write_file()` and an exclusive `i_writecount` test — and setting the compression flag and truncating require only ownership/write permission on the attacker's own file. An ordinary unprivileged user (or an Android app on its own data files) can perform the full sequence.\nUI:N - The attacker creates, flags, writes, releases, and truncates their own file on an already-mounted filesystem; no victim needs to mount anything, open anything, or act in any way.\nS:U - The corruption is confined to the kernel/filesystem security authority that already manages the affected volume; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - The defect is block-accounting metadata desync (`i_blocks` / `total_valid_block_count` vs. the dnode); the newly allocated block is freshly written with the file's own decompressed data and no stale, out-of-bounds, or cross-file content is ever exposed to the attacker.\nI:H - It causes persistent, on-disk corruption of shared filesystem metadata — the inode's `i_blocks`, `i_compr_blocks` and the checkpoint's global `valid_block_count` — which survives reboot, is confirmed by fsck failure, and is not confined to the attacker's own file since the superblock/checkpoint accounting governs the whole volume.\nA:H - The skewed accounting reaches `f2fs_bug_on()` in `dec_valid_block_count()` and, once the over-reported free space is exhausted, `get_new_segment()`'s `f2fs_stop_checkpoint(STOP_CP_REASON_NO_SEGMENT)` + `f2fs_bug_on(sbi, 1)` — a kernel BUG/panic under `CONFIG_F2FS_CHECK_FS`, otherwise a shut-down checkpoint that makes the filesystem return `-EIO` for everything and require offline fsck." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/f2fs/file.c" ], "versions": [ { "version": "8e1651cd667cd6779db28314844d88b6de8312a3", "lessThan": "b8962cf98595d1ec62f40f23667de830567ec8bc", "status": "affected", "versionType": "git" }, { "version": "c61404153eb683da9c35aad133131554861ed561", "lessThan": "8acae047215024d1ac499b3c8337ef1b952f160b", "status": "affected", "versionType": "git" }, { "version": "c61404153eb683da9c35aad133131554861ed561", "lessThan": "3ccf5210dc941a7aa0180596ac021568be4d35ec", "status": "affected", "versionType": "git" }, { "version": "c61404153eb683da9c35aad133131554861ed561", "lessThan": "9f9341064a9b5246a32a7fe56b9f80c6f7f3c62d", "status": "affected", "versionType": "git" }, { "version": "c61404153eb683da9c35aad133131554861ed561", "lessThan": "5268241b41b1c5d0acca75e9b97d4fd719251c8c", "status": "affected", "versionType": "git" }, { "version": "c61404153eb683da9c35aad133131554861ed561", "lessThan": "29ed2b5dd521ce7c5d8466cd70bf0cc9d07afeee", "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/f2fs/file.c" ], "versions": [ { "version": "5.14", "status": "affected" }, { "version": "0", "lessThan": "5.14", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.161", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.93", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.33", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.4", "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": "5.14", "versionEndExcluding": "5.15.161" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.1.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.6.33" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.9.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.10" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/b8962cf98595d1ec62f40f23667de830567ec8bc" }, { "url": "https://git.kernel.org/stable/c/8acae047215024d1ac499b3c8337ef1b952f160b" }, { "url": "https://git.kernel.org/stable/c/3ccf5210dc941a7aa0180596ac021568be4d35ec" }, { "url": "https://git.kernel.org/stable/c/9f9341064a9b5246a32a7fe56b9f80c6f7f3c62d" }, { "url": "https://git.kernel.org/stable/c/5268241b41b1c5d0acca75e9b97d4fd719251c8c" }, { "url": "https://git.kernel.org/stable/c/29ed2b5dd521ce7c5d8466cd70bf0cc9d07afeee" } ], "title": "f2fs: compress: don't allow unaligned truncation on released compress 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