f2fs: read COW data with the original inode during atomic write

{
  "id": "140fd5434aed9df62a038ca43ba0478b35f01380aaf926b26ecdfc8282110a28",
  "url": "https://osv.dev/vulnerability/CVE-2026-63811",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "f2fs: read COW data with the original inode during atomic write",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: f2fs: read COW data with the original inode during atomic write When updating an atomic-write file, f2fs_write_begin() may read the previously written data back from the COW inode: prepare_atomic_write_begin() locates the block in the COW inode and sets use_cow, and the read bio is then built with the COW inode: f2fs_submit_page_read(use_cow ? F2FS_I(inode)->cow_inode : inode, ...); and f2fs_grab_read_bio() decides whether to schedule fs-layer decryption (STEP_DECRYPT) for the bio based on that inode via fscrypt_inode_uses_fs_layer_crypto(). However, the folio being filled belongs to the original inode (folio->mapping->host == inode), and the data stored in the COW block was encrypted (or left as plaintext) using the original inode's context, not the COW inode's -- see f2fs_encrypt_one_page(), which keys off fio->page->mapping->host. fscrypt_decrypt_pagecache_blocks() likewise operates on folio->mapping->host. The COW inode is created as a tmpfile in the parent directory and inherits its encryption policy from there. With test_dummy_encryption the newly created COW inode gets the dummy policy and becomes encrypted, while a pre-existing regular file -- created before the policy applied, e.g. already present in the on-disk image -- stays unencrypted. The read path then sets STEP_DECRYPT based on the encrypted COW inode and calls fscrypt_decrypt_pagecache_blocks() on a folio whose host (the unencrypted original ",
    "evidence": "osv:CVE-2026-63811",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.160",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.114",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.57",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-63811",
      "aliases": [
        "CVE-2026-63811"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "591fc34e1f98b0d7eef4aa3440bfdff3c5a1cadd"
                },
                {
                  "fixed": "bcc9df992f3cbc43f2ecfe0b22e428e50f326e72"
                },
                {
                  "fixed": "655d55c5740d37ffdf6233ff5fe21cea879407f1"
                },
                {
                  "fixed": "7e4ab3907f44dc243d026048d7f5d477dae9267b"
                },
                {
                  "fixed": "a92332f32a8d31a7eee47b1dc1d751cb3319908f"
                },
                {
                  "fixed": "a41075acde0124d2f8a5f563068a5d63e8ffd57b"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63811.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.4.0"
                },
                {
                  "fixed": "6.6.160"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.114"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.57"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63811.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:32.560839446Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/655d55c5740d37ffdf6233ff5fe21cea879407f1",
        "https://git.kernel.org/stable/c/7e4ab3907f44dc243d026048d7f5d477dae9267b",
        "https://git.kernel.org/stable/c/a41075acde0124d2f8a5f563068a5d63e8ffd57b",
        "https://git.kernel.org/stable/c/a92332f32a8d31a7eee47b1dc1d751cb3319908f",
        "https://git.kernel.org/stable/c/bcc9df992f3cbc43f2ecfe0b22e428e50f326e72",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63811.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-63811",
        "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-2026-63811.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-63811",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 499706,
  "published_at": "2026-07-19T12:02:13.057+00:00"
}