CVE-2025-21654 (GCVE-0-2025-21654)
Vulnerability from cvelistv5
Published
2025-01-19 10:18
Modified
2025-05-04 07:18
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ovl: support encoding fid from inode with no alias Dmitry Safonov reported that a WARN_ON() assertion can be trigered by userspace when calling inotify_show_fdinfo() for an overlayfs watched inode, whose dentry aliases were discarded with drop_caches. The WARN_ON() assertion in inotify_show_fdinfo() was removed, because it is possible for encoding file handle to fail for other reason, but the impact of failing to encode an overlayfs file handle goes beyond this assertion. As shown in the LTP test case mentioned in the link below, failure to encode an overlayfs file handle from a non-aliased inode also leads to failure to report an fid with FAN_DELETE_SELF fanotify events. As Dmitry notes in his analyzis of the problem, ovl_encode_fh() fails if it cannot find an alias for the inode, but this failure can be fixed. ovl_encode_fh() seldom uses the alias and in the case of non-decodable file handles, as is often the case with fanotify fid info, ovl_encode_fh() never needs to use the alias to encode a file handle. Defer finding an alias until it is actually needed so ovl_encode_fh() will not fail in the common case of FAN_DELETE_SELF fanotify events.
References
Impacted products
Vendor Product Version
Linux Linux Version: 16aac5ad1fa94894b798dd522c5c3a6a0628d7f0
Version: 16aac5ad1fa94894b798dd522c5c3a6a0628d7f0
Version: 16aac5ad1fa94894b798dd522c5c3a6a0628d7f0
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/overlayfs/export.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f0c0ac84de17c37e6e84da65fb920f91dada55ad",
              "status": "affected",
              "version": "16aac5ad1fa94894b798dd522c5c3a6a0628d7f0",
              "versionType": "git"
            },
            {
              "lessThan": "3c7c90274ae339e1ad443c9be1c67a20b80b9c76",
              "status": "affected",
              "version": "16aac5ad1fa94894b798dd522c5c3a6a0628d7f0",
              "versionType": "git"
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            {
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/overlayfs/export.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
            {
              "lessThan": "6.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.74",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.13",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.74",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.10",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\novl: support encoding fid from inode with no alias\n\nDmitry Safonov reported that a WARN_ON() assertion can be trigered by\nuserspace when calling inotify_show_fdinfo() for an overlayfs watched\ninode, whose dentry aliases were discarded with drop_caches.\n\nThe WARN_ON() assertion in inotify_show_fdinfo() was removed, because\nit is possible for encoding file handle to fail for other reason, but\nthe impact of failing to encode an overlayfs file handle goes beyond\nthis assertion.\n\nAs shown in the LTP test case mentioned in the link below, failure to\nencode an overlayfs file handle from a non-aliased inode also leads to\nfailure to report an fid with FAN_DELETE_SELF fanotify events.\n\nAs Dmitry notes in his analyzis of the problem, ovl_encode_fh() fails\nif it cannot find an alias for the inode, but this failure can be fixed.\novl_encode_fh() seldom uses the alias and in the case of non-decodable\nfile handles, as is often the case with fanotify fid info,\novl_encode_fh() never needs to use the alias to encode a file handle.\n\nDefer finding an alias until it is actually needed so ovl_encode_fh()\nwill not fail in the common case of FAN_DELETE_SELF fanotify events."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-04T07:18:19.475Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f0c0ac84de17c37e6e84da65fb920f91dada55ad"
        },
        {
          "url": "https://git.kernel.org/stable/c/3c7c90274ae339e1ad443c9be1c67a20b80b9c76"
        },
        {
          "url": "https://git.kernel.org/stable/c/c45beebfde34aa71afbc48b2c54cdda623515037"
        }
      ],
      "title": "ovl: support encoding fid from inode with no alias",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21654",
    "datePublished": "2025-01-19T10:18:11.104Z",
    "dateReserved": "2024-12-29T08:45:45.729Z",
    "dateUpdated": "2025-05-04T07:18:19.475Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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