{"id":"CVE-2026-74350","state":"PUBLISHED","title":"ocfs2: validate fast symlink target during inode read","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: validate fast symlink target during inode read\n\nocfs2_validate_inode_block() already rejects several inconsistent\nself-contained dinodes before they are exposed to the rest of the\nfilesystem.  Fast symlinks need the same treatment.\n\nA zero-cluster symlink is treated as a fast symlink and later read through\npage_get_link() and ocfs2_fast_symlink_read_folio().  That path uses\nstrnlen() on the inline payload and then copies len + 1 bytes into the\nfolio.  If a corrupt dinode stores an i_size that does not fit the inline\narea or omits the terminating NUL at i_size, that copy reads past the end\nof the inode block buffer.\n\nReject zero-cluster symlink dinodes whose i_size exceeds the inline\nfast-symlink capacity or whose inline payload is not NUL-terminated\nexactly at i_size when the inode block is validated.  This keeps malformed\nfast symlinks from reaching the read path.\n\nValidation reproduced this kernel report:\nKASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0\nRIP: 0033:0x7f5c6d859aa7\nRead of size 3905\nCall trace:\n  dump_stack_lvl+0x66/0xa0 (?:?)\n  print_report+0xce/0x630 (?:?)\n  ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?)\n  srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n  __virt_addr_valid+0x19f/0x330 (?:?)\n  kasan_report+0xe0/0x110 (?:?)\n  kasan_check_range+0x105/0x1b0 (?:?)\n  __asan_memcpy+0x23/0x60 (?:?)\n  filemap_read_folio+0x27/0xe0 (?:?)\n  filemap_read_folio+0x35/0xe0 (?:?)\n  do_read_cache_folio+0x138/0x230 (?:?)\n  __page_get_link+0x26/0x110 (?:?)\n  page_get_link+0x2e/0x70 (?:?)\n  vfs_readlink+0x15e/0x250 (?:?)\n  touch_atime+0x4d/0x370 (?:?)\n  do_readlinkat+0x186/0x200 (?:?)\n  do_user_addr_fault+0x65a/0x890 (?:?)\n  __x64_sys_readlink+0x46/0x60 (?:?)\n  do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)","publishedAt":"2026-08-15T05:58:37.298Z","updatedAt":"2026-10-30T12:29:50.024Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"ed9f95ee3bbaea9b05808727eb86ea5e5ccf2b52","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"dcabbf7da43825e23e5e89adccc1430faee1bce1","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"030d4caae89977b80349df95523dfda1dfb10f73","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"d94bf50756d7f80bb728ad58246376649e1035b6","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"f9e2cb692b77a679b1f4cc2b7b277fa908586533","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"e234973f286ed2e8961a24561ec91594ec3e3ff8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ocfs2/inode.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.5","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.5","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ocfs2/inode.c"]}],"references":["https://git.kernel.org/stable/c/ed9f95ee3bbaea9b05808727eb86ea5e5ccf2b52","https://git.kernel.org/stable/c/dcabbf7da43825e23e5e89adccc1430faee1bce1","https://git.kernel.org/stable/c/030d4caae89977b80349df95523dfda1dfb10f73","https://git.kernel.org/stable/c/d94bf50756d7f80bb728ad58246376649e1035b6","https://git.kernel.org/stable/c/f9e2cb692b77a679b1f4cc2b7b277fa908586533","https://git.kernel.org/stable/c/e234973f286ed2e8961a24561ec91594ec3e3ff8"],"weaknesses":[],"ingestedAt":"2026-10-30T12:48:04.825Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74350.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74350","state":"PUBLISHED","datePublished":"2026-08-15T05:58:37.298Z","dateUpdated":"2026-10-30T12:29:50.024Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.886Z"},"containers":{"cna":{"title":"ocfs2: validate fast symlink target during inode read","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: validate fast symlink target during inode read\n\nocfs2_validate_inode_block() already rejects several inconsistent\nself-contained dinodes before they are exposed to the rest of the\nfilesystem.  Fast symlinks need the same treatment.\n\nA zero-cluster symlink is treated as a fast symlink and later read through\npage_get_link() and ocfs2_fast_symlink_read_folio().  That path uses\nstrnlen() on the inline payload and then copies len + 1 bytes into the\nfolio.  If a corrupt dinode stores an i_size that does not fit the inline\narea or omits the terminating NUL at i_size, that copy reads past the end\nof the inode block buffer.\n\nReject zero-cluster symlink dinodes whose i_size exceeds the inline\nfast-symlink capacity or whose inline payload is not NUL-terminated\nexactly at i_size when the inode block is validated.  This keeps malformed\nfast symlinks from reaching the read path.\n\nValidation reproduced this kernel report:\nKASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0\nRIP: 0033:0x7f5c6d859aa7\nRead of size 3905\nCall trace:\n  dump_stack_lvl+0x66/0xa0 (?:?)\n  print_report+0xce/0x630 (?:?)\n  ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?)\n  srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n  __virt_addr_valid+0x19f/0x330 (?:?)\n  kasan_report+0xe0/0x110 (?:?)\n  kasan_check_range+0x105/0x1b0 (?:?)\n  __asan_memcpy+0x23/0x60 (?:?)\n  filemap_read_folio+0x27/0xe0 (?:?)\n  filemap_read_folio+0x35/0xe0 (?:?)\n  do_read_cache_folio+0x138/0x230 (?:?)\n  __page_get_link+0x26/0x110 (?:?)\n  page_get_link+0x2e/0x70 (?:?)\n  vfs_readlink+0x15e/0x250 (?:?)\n  touch_atime+0x4d/0x370 (?:?)\n  do_readlinkat+0x186/0x200 (?:?)\n  do_user_addr_fault+0x65a/0x890 (?:?)\n  __x64_sys_readlink+0x46/0x60 (?:?)\n  do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"ed9f95ee3bbaea9b05808727eb86ea5e5ccf2b52","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"dcabbf7da43825e23e5e89adccc1430faee1bce1","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"030d4caae89977b80349df95523dfda1dfb10f73","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"d94bf50756d7f80bb728ad58246376649e1035b6","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"f9e2cb692b77a679b1f4cc2b7b277fa908586533","versionType":"git"},{"version":"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1","status":"affected","lessThan":"e234973f286ed2e8961a24561ec91594ec3e3ff8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ocfs2/inode.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.5","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.5","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ocfs2/inode.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/ed9f95ee3bbaea9b05808727eb86ea5e5ccf2b52"},{"url":"https://git.kernel.org/stable/c/dcabbf7da43825e23e5e89adccc1430faee1bce1"},{"url":"https://git.kernel.org/stable/c/030d4caae89977b80349df95523dfda1dfb10f73"},{"url":"https://git.kernel.org/stable/c/d94bf50756d7f80bb728ad58246376649e1035b6"},{"url":"https://git.kernel.org/stable/c/f9e2cb692b77a679b1f4cc2b7b277fa908586533"},{"url":"https://git.kernel.org/stable/c/e234973f286ed2e8961a24561ec91594ec3e3ff8"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - OCFS2 cluster nodes commonly NFS-export shared LUNs; nfsd READLINK reaches vfs_readlink→page_get_link→ocfs2_fast_symlink_read_folio on a forged zero-cluster symlink dinode on the volume, giving a remote network attack path without a local syscall.\nAC:L - A forged dinode fully controls i_size and inline bytes; strnlen() bounded only by ocfs2_fast_symlink_chars() then memcpy_to_folio() copies len+1 past the inode buffer_head (KASAN read ~3905), deterministically and without races.\nPR:N - Triggering needs only permission to read the symlink: a remote NFS client on an exported share, or any unprivileged local/cluster user; planting the malformed dinode uses attacker-controlled on-disk metadata on shared storage, not init-namespace root on the victim.\nUI:N - Once the corrupt fast symlink exists on a mounted/exported volume, readlink(2), NFS READLINK, or path lookup via get_link automatically pulls the inline target through ocfs2_fast_symlink_read_folio with no further deliberate victim action.\nS:U - Impact stays within the host kernel parsing the OCFS2 symlink (memory disclosure/crash/privilege escalation on the server); no VM escape, IOMMU bypass, or cross-authority scope change.\nC:H - memcpy_to_folio() performs an out-of-bounds read up to ~3900 bytes past the inode block buffer (KASAN UAF/slab read of size 3905); OOB/UAF kernel reads enable arbitrary adjacent-heap disclosure.\nI:H - The same unvalidated strnlen/memcpy path corrupts kernel memory semantics (KASAN UAF) and, per kernel CNA guidance, UAF/OOB reads adjacent slab objects can be leveraged into write/control-flow primitives via heap grooming.\nA:H - KASAN reports use-after-free in ocfs2_fast_symlink_read_folio during the over-wide memcpy; such kernel memory faults typically oops/panic the host, fully denying availability."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:29:50.024Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.5","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.5","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.5","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.5","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.5","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.5","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}