{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2022-49170","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-02-26T01:49:39.279Z","datePublished":"2025-02-26T01:55:27.562Z","dateUpdated":"2026-08-12T23:58:11.094Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-12T23:58:11.094Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to do sanity check on curseg->alloc_type\n\nAs Wenqing Liu reported in bugzilla:\n\nhttps://bugzilla.kernel.org/show_bug.cgi?id=215657\n\n- Overview\nUBSAN: array-index-out-of-bounds in fs/f2fs/segment.c:3460:2 when mount and operate a corrupted image\n\n- Reproduce\ntested on kernel 5.17-rc4, 5.17-rc6\n\n1. mkdir test_crash\n2. cd test_crash\n3. unzip tmp2.zip\n4. mkdir mnt\n5. ./single_test.sh f2fs 2\n\n- Kernel dump\n[   46.434454] loop0: detected capacity change from 0 to 131072\n[   46.529839] F2FS-fs (loop0): Mounted with checkpoint version = 7548c2d9\n[   46.738319] ================================================================================\n[   46.738412] UBSAN: array-index-out-of-bounds in fs/f2fs/segment.c:3460:2\n[   46.738475] index 231 is out of range for type 'unsigned int [2]'\n[   46.738539] CPU: 2 PID: 939 Comm: umount Not tainted 5.17.0-rc6 #1\n[   46.738547] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014\n[   46.738551] Call Trace:\n[   46.738556]  <TASK>\n[   46.738563]  dump_stack_lvl+0x47/0x5c\n[   46.738581]  ubsan_epilogue+0x5/0x50\n[   46.738592]  __ubsan_handle_out_of_bounds+0x68/0x80\n[   46.738604]  f2fs_allocate_data_block+0xdff/0xe60 [f2fs]\n[   46.738819]  do_write_page+0xef/0x210 [f2fs]\n[   46.738934]  f2fs_do_write_node_page+0x3f/0x80 [f2fs]\n[   46.739038]  __write_node_page+0x2b7/0x920 [f2fs]\n[   46.739162]  f2fs_sync_node_pages+0x943/0xb00 [f2fs]\n[   46.739293]  f2fs_write_checkpoint+0x7bb/0x1030 [f2fs]\n[   46.739405]  kill_f2fs_super+0x125/0x150 [f2fs]\n[   46.739507]  deactivate_locked_super+0x60/0xc0\n[   46.739517]  deactivate_super+0x70/0xb0\n[   46.739524]  cleanup_mnt+0x11a/0x200\n[   46.739532]  __cleanup_mnt+0x16/0x20\n[   46.739538]  task_work_run+0x67/0xa0\n[   46.739547]  exit_to_user_mode_prepare+0x18c/0x1a0\n[   46.739559]  syscall_exit_to_user_mode+0x26/0x40\n[   46.739568]  do_syscall_64+0x46/0xb0\n[   46.739584]  entry_SYSCALL_64_after_hwframe+0x44/0xae\n\nThe root cause is we missed to do sanity check on curseg->alloc_type,\nresult in out-of-bound accessing on sbi->block_count[] array, fix it."}],"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 bug is reached only through the local f2fs mount/VFS path (mount crafted image → write/sync/umount → f2fs_allocate_data_block → stat_inc_block_count), not via network protocol handlers or packet processing.\nAC:L - A crafted checkpoint with an invalid curseg alloc_type (unsigned char, attacker-chosen) deterministically causes an out-of-bounds increment of sbi->block_count[] once allocation runs; CONFIG_F2FS_STAT_FS defaults to y and no attacker-uncontrollable race is required.\nPR:L - After the malicious f2fs volume is mounted (Android/udisks automount of removable media, or shared workstation), an unprivileged local user can trigger allocation via ordinary writes/sync; CAP_SYS_ADMIN is not required on that path (f2fs is not FS_USERNS_MOUNT, but mount itself is not required once the image is already mounted).\nUI:N - Once the crafted image is present and mounted via automount or delegated mount rights, the attacker drives block allocation themselves through write/sync/umount with no further separate victim action.\nS:U - Corruption and crash remain within the host kernel’s f2fs/sbi memory authority; this is standard local kernel impact, not a VM escape, IOMMU bypass, or other cross-boundary break.\nC:H - Attacker-controlled alloc_type indexes past block_count[2] into adjacent f2fs_sb_info fields (pointers, kobjects, locks), which is out-of-bounds memory corruption leverageable for kernel information disclosure under the overestimate-severity rule.\nI:H - The same OOB is a write primitive (block_count[idx]++), and repeated allocations let the attacker increment a chosen offset many times into critical sbi fields, enabling heap/metadata corruption and control-flow impact.\nA:H - The reported UBSAN out-of-bounds access in f2fs_allocate_data_block on umount/writeback can oops or panic the kernel when the corrupted sbi fields are later used, yielding a full denial of service."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/f2fs/segment.c"],"versions":[{"version":"351df4b201157351c7d26bf12c3eeb9dbce98854","lessThan":"498b7088db71f9707359448cd6800bbb1882f4c3","status":"affected","versionType":"git"},{"version":"351df4b201157351c7d26bf12c3eeb9dbce98854","lessThan":"f68caedf264a95c0b02dfd0d9f92ac2637d5848a","status":"affected","versionType":"git"},{"version":"351df4b201157351c7d26bf12c3eeb9dbce98854","lessThan":"0748a0f7dcb9d9dddc80302d73ebcecef6782ef0","status":"affected","versionType":"git"},{"version":"351df4b201157351c7d26bf12c3eeb9dbce98854","lessThan":"c12765e3f129b144421c80d3383df885f85ee290","status":"affected","versionType":"git"},{"version":"351df4b201157351c7d26bf12c3eeb9dbce98854","lessThan":"f41ee8b91c00770d718be2ff4852a80017ae9ab3","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/segment.c"],"versions":[{"version":"3.8","status":"affected"},{"version":"0","lessThan":"3.8","status":"unaffected","versionType":"semver"},{"version":"5.10.110","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.33","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"5.16.19","lessThanOrEqual":"5.16.*","status":"unaffected","versionType":"semver"},{"version":"5.17.2","lessThanOrEqual":"5.17.*","status":"unaffected","versionType":"semver"},{"version":"5.18","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":"3.8","versionEndExcluding":"5.10.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.15.33"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.16.19"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.17.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.18"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/498b7088db71f9707359448cd6800bbb1882f4c3"},{"url":"https://git.kernel.org/stable/c/f68caedf264a95c0b02dfd0d9f92ac2637d5848a"},{"url":"https://git.kernel.org/stable/c/0748a0f7dcb9d9dddc80302d73ebcecef6782ef0"},{"url":"https://git.kernel.org/stable/c/c12765e3f129b144421c80d3383df885f85ee290"},{"url":"https://git.kernel.org/stable/c/f41ee8b91c00770d718be2ff4852a80017ae9ab3"}],"title":"f2fs: fix to do sanity check on curseg->alloc_type","x_generator":{"engine":"bippy-1.2.0"}}}}