{"id":"CVE-2024-33847","state":"PUBLISHED","title":"f2fs: compress: don't allow unaligned truncation on released compress inode","description":"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.","publishedAt":"2024-06-24T13:56:48.723Z","updatedAt":"2026-10-15T00:40:43.234Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux 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compress: don't allow unaligned truncation on released compress inode","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8e1651cd667cd6779db28314844d88b6de8312a3","status":"affected","lessThan":"b8962cf98595d1ec62f40f23667de830567ec8bc","versionType":"git"},{"version":"c61404153eb683da9c35aad133131554861ed561","status":"affected","lessThan":"8acae047215024d1ac499b3c8337ef1b952f160b","versionType":"git"},{"version":"c61404153eb683da9c35aad133131554861ed561","status":"affected","lessThan":"3ccf5210dc941a7aa0180596ac021568be4d35ec","versionType":"git"},{"version":"c61404153eb683da9c35aad133131554861ed561","status":"affected","lessThan":"9f9341064a9b5246a32a7fe56b9f80c6f7f3c62d","versionType":"git"},{"version":"c61404153eb683da9c35aad133131554861ed561","status":"affected","lessThan":"5268241b41b1c5d0acca75e9b97d4fd719251c8c","versionType":"git"},{"version":"c61404153eb683da9c35aad133131554861ed561","status":"affected","lessThan":"29ed2b5dd521ce7c5d8466cd70bf0cc9d07afeee","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/file.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.14","versionType":"semver"},{"version":"5.15.161","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.93","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.33","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.9.4","status":"unaffected","lessThanOrEqual":"6.9.*","versionType":"semver"},{"version":"6.10","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/file.c"]}],"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:29:51.830Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2024-06-25T13:51:44.928910Z","id":"CVE-2024-33847","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-06-25T13:51:56.043Z"}},{"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/b8962cf98595d1ec62f40f23667de830567ec8bc","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/8acae047215024d1ac499b3c8337ef1b952f160b","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/3ccf5210dc941a7aa0180596ac021568be4d35ec","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/9f9341064a9b5246a32a7fe56b9f80c6f7f3c62d","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/5268241b41b1c5d0acca75e9b97d4fd719251c8c","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/29ed2b5dd521ce7c5d8466cd70bf0cc9d07afeee","tags":["x_transferred"]}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2024-08-02T02:42:58.909Z"}},{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 TM MFP - GNU/Linux subsystem","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"V1.1.1","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-265688.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-15T00:40:43.234Z"},"x_adpType":"supplier"}]}}}