CVE-2026-74350 (GCVE-0-2026-74350)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:58 – Updated: 2026-08-17 05:46
VLAI
Title
ocfs2: validate fast symlink target during inode read
Summary
In the Linux kernel, the following vulnerability has been resolved: ocfs2: validate fast symlink target during inode read ocfs2_validate_inode_block() already rejects several inconsistent self-contained dinodes before they are exposed to the rest of the filesystem. Fast symlinks need the same treatment. A zero-cluster symlink is treated as a fast symlink and later read through page_get_link() and ocfs2_fast_symlink_read_folio(). That path uses strnlen() on the inline payload and then copies len + 1 bytes into the folio. If a corrupt dinode stores an i_size that does not fit the inline area or omits the terminating NUL at i_size, that copy reads past the end of the inode block buffer. Reject zero-cluster symlink dinodes whose i_size exceeds the inline fast-symlink capacity or whose inline payload is not NUL-terminated exactly at i_size when the inode block is validated. This keeps malformed fast symlinks from reaching the read path. Validation reproduced this kernel report: KASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0 RIP: 0033:0x7f5c6d859aa7 Read of size 3905 Call trace: dump_stack_lvl+0x66/0xa0 (?:?) print_report+0xce/0x630 (?:?) ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x19f/0x330 (?:?) kasan_report+0xe0/0x110 (?:?) kasan_check_range+0x105/0x1b0 (?:?) __asan_memcpy+0x23/0x60 (?:?) filemap_read_folio+0x27/0xe0 (?:?) filemap_read_folio+0x35/0xe0 (?:?) do_read_cache_folio+0x138/0x230 (?:?) __page_get_link+0x26/0x110 (?:?) page_get_link+0x2e/0x70 (?:?) vfs_readlink+0x15e/0x250 (?:?) touch_atime+0x4d/0x370 (?:?) do_readlinkat+0x186/0x200 (?:?) do_user_addr_fault+0x65a/0x890 (?:?) __x64_sys_readlink+0x46/0x60 (?:?) do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1 , < f9e2cb692b77a679b1f4cc2b7b277fa908586533 (git)
Affected: ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1 , < e234973f286ed2e8961a24561ec91594ec3e3ff8 (git)
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Linux Linux Affected: 3.5
Unaffected: 0 , < 3.5 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ocfs2/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1",
              "versionType": "git"
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              "status": "affected",
              "version": "ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1",
              "versionType": "git"
            }
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ocfs2/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.5"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "3.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "3.5",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
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      ],
      "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 (?:?)"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - OCFS2 cluster nodes commonly NFS-export shared LUNs; nfsd READLINK reaches vfs_readlink\u2192page_get_link\u2192ocfs2_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": {
        "dateUpdated": "2026-08-17T05:46:13.886Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f9e2cb692b77a679b1f4cc2b7b277fa908586533"
        },
        {
          "url": "https://git.kernel.org/stable/c/e234973f286ed2e8961a24561ec91594ec3e3ff8"
        }
      ],
      "title": "ocfs2: validate fast symlink target during inode read",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74350",
    "datePublished": "2026-08-15T05:58:37.298Z",
    "dateReserved": "2026-08-15T05:44:03.886Z",
    "dateUpdated": "2026-08-17T05:46:13.886Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-74350",
      "date": "2026-08-18",
      "epss": "0.00379",
      "percentile": "0.31063"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74350\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-15T06:22:36.270\",\"lastModified\":\"2026-08-17T06:19:29.677\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ocfs2/inode.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1\",\"lessThan\":\"f9e2cb692b77a679b1f4cc2b7b277fa908586533\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1\",\"lessThan\":\"e234973f286ed2e8961a24561ec91594ec3e3ff8\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/ocfs2/inode.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"3.5\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"3.5\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"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\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/e234973f286ed2e8961a24561ec91594ec3e3ff8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f9e2cb692b77a679b1f4cc2b7b277fa908586533\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}



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