f2fs: validate ACL entry sizes in f2fs_acl_from_disk()

{
  "id": "0cf328d6df71aad951f527bf88429decff1916796a08c256afed566ab3a229c3",
  "url": "https://osv.dev/vulnerability/CVE-2026-63814",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "f2fs: validate ACL entry sizes in f2fs_acl_from_disk()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: f2fs: validate ACL entry sizes in f2fs_acl_from_disk() f2fs_acl_count() only validates the aggregate ACL xattr length. A malformed ACL can still place ACL_USER or ACL_GROUP in a slot that only contains struct f2fs_acl_entry_short bytes, and f2fs_acl_from_disk() then reads entry->e_id before verifying that a full entry fits. Require a short entry before reading e_tag and e_perm, and require a full entry before reading e_id for ACL_USER and ACL_GROUP. Return -EFSCORRUPTED from these new truncated-entry checks, while keeping the pre-existing -EINVAL paths unchanged. Validation reproduced this kernel report: KASAN slab-out-of-bounds in __f2fs_get_acl+0x6fb/0x7e0 RIP: 0033:0x7f4b835ea7aa The buggy address belongs to the object at ffff888114589960 which belongs to the cache kmalloc-8 of size 8 The buggy address is located 0 bytes to the right of allocated 8-byte region [ffff888114589960, ffff888114589968) Read of size 4 Call trace: dump_stack_lvl+0x66/0xa0 (?:?) print_report+0xce/0x630 (?:?) __f2fs_get_acl+0x6fb/0x7e0 (fs/f2fs/acl.c:169) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x224/0x430 (?:?) kasan_report+0xe0/0x110 (?:?) __f2fs_get_acl+0x5/0x7e0 (fs/f2fs/acl.c:169) __get_acl+0x281/0x380 (?:?) vfs_get_acl+0x10b/0x190 (?:?) do_get_acl+0x2a/0x410 (?:?) do_get_acl+0x9/0x410 (?:?) do_getxattr+0xe8/0x260 (?:?) filename_getxattr+0xd1/0x140 (?:?) do_getname+0x2d/0x2d0 (?:?) path_getxattrat+0x16c/0x20",
    "evidence": "osv:CVE-2026-63814",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-63814",
      "aliases": [
        "CVE-2026-63814"
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      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
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      "modified": "2026-10-28T02:30:26.480120828Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1ddf3fd21c4c652f9cab5552515c04a166662306",
        "https://git.kernel.org/stable/c/442ca20c54038e2400cf28aaa944cf1de2c8e65d",
        "https://git.kernel.org/stable/c/4e2a96ec7236e248e706850568e0a925fd21b588",
        "https://git.kernel.org/stable/c/5d8a39649947a4e86c8fbc682d7fc0041b8d109a",
        "https://git.kernel.org/stable/c/733cd8474e6d763d75ed96f3f2b98a25480cf2b9",
        "https://git.kernel.org/stable/c/aba4f94ac1832c7299c33e1b4fe5f87eef6dc8f1",
        "https://git.kernel.org/stable/c/c4810ada31e80cbe4011467c4f3b1e93f94134f3",
        "https://git.kernel.org/stable/c/ff83de56882cb8466184d322abece2589258ca56",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63814.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-63814",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63814.json"
      }
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    "related_cves": [
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        "value": "CVE-2026-63814",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 493108,
  "published_at": "2026-07-19T12:02:14.771+00:00"
}