Vulnerability-Lookup

GHSA-7HQ4-C7JG-2H9H

Vulnerability from github – Published: 2026-10-23 15:31 – Updated: 2026-10-24 15:32

Details

In the Linux kernel, the following vulnerability has been resolved:

fsverity: RCU-delay the freeing of struct fsverity_info

__fsverity_get_info() calls rhashtable_lookup_fast(), which just uses rcu_read_lock() and doesn't directly synchronize with fsverity_remove_info().

For the same inode this isn't a problem: its fsverity_info is removed only at inode eviction time or upon failure to enable verity, when the inode no longer needs its fsverity_info and it will no longer be accessed via that inode.

However, this is broken and can cause a use-after-free for concurrent __fsverity_get_info() for different inodes. Those rely on following fsverity_info::rhash_head in the rhashtable under rcu_read_lock() only. They also use fsverity_info::inode to do the key comparison.

Fix this by RCU-delaying the freeing of 'struct fsverity_info' after it's been removed from the rhashtable.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-99051"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-23T13:17:28Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfsverity: RCU-delay the freeing of struct fsverity_info\n\n__fsverity_get_info() calls rhashtable_lookup_fast(), which just uses\nrcu_read_lock() and doesn\u0027t directly synchronize with\nfsverity_remove_info().\n\nFor the same inode this isn\u0027t a problem: its fsverity_info is removed\nonly at inode eviction time or upon failure to enable verity, when the\ninode no longer needs its fsverity_info and it will no longer be\naccessed via that inode.\n\nHowever, this is broken and can cause a use-after-free for concurrent\n__fsverity_get_info() for *different* inodes.  Those rely on following\nfsverity_info::rhash_head in the rhashtable under rcu_read_lock() only.\nThey also use fsverity_info::inode to do the key comparison.\n\nFix this by RCU-delaying the freeing of \u0027struct fsverity_info\u0027 after\nit\u0027s been removed from the rhashtable.",
  "id": "GHSA-7hq4-c7jg-2h9h",
  "modified": "2026-10-24T15:32:50Z",
  "published": "2026-10-23T15:31:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99051"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e58c3805ed325fe2d4ae2dd467c0486cc860b733"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fa84f091a8e7fc46fd29834496fab9739dd4c8dc"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-99051 (GCVE-0-2026-99051)

Vulnerability from cvelistv5 – Published: 2026-10-23 12:22 – Updated: 2026-10-24 14:10

Title

fsverity: RCU-delay the freeing of struct fsverity_info

Summary

In the Linux kernel, the following vulnerability has been resolved: fsverity: RCU-delay the freeing of struct fsverity_info __fsverity_get_info() calls rhashtable_lookup_fast(), which just uses rcu_read_lock() and doesn't directly synchronize with fsverity_remove_info(). For the same inode this isn't a problem: its fsverity_info is removed only at inode eviction time or upon failure to enable verity, when the inode no longer needs its fsverity_info and it will no longer be accessed via that inode. However, this is broken and can cause a use-after-free for concurrent __fsverity_get_info() for *different* inodes. Those rely on following fsverity_info::rhash_head in the rhashtable under rcu_read_lock() only. They also use fsverity_info::inode to do the key comparison. Fix this by RCU-delaying the freeing of 'struct fsverity_info' after it's been removed from the rhashtable.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7056 records in the last 180 days details

References

2 references

URL	Tags
https://git.kernel.org/stable/c/fa84f091a8e7fc46f…
https://git.kernel.org/stable/c/e58c3805ed325fe2d…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f77f281b61183a5c0b87e6a4d101c70bd32c1c79 , < fa84f091a8e7fc46fd29834496fab9739dd4c8dc (git) Affected: f77f281b61183a5c0b87e6a4d101c70bd32c1c79 , < e58c3805ed325fe2d4ae2dd467c0486cc860b733 (git)
Linux	Linux	Affected: 7.0 Unaffected: 0 , < 7.0 (semver) Unaffected: 7.2.11 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/verity/fsverity_private.h",
            "fs/verity/open.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "fa84f091a8e7fc46fd29834496fab9739dd4c8dc",
              "status": "affected",
              "version": "f77f281b61183a5c0b87e6a4d101c70bd32c1c79",
              "versionType": "git"
            },
            {
              "lessThan": "e58c3805ed325fe2d4ae2dd467c0486cc860b733",
              "status": "affected",
              "version": "f77f281b61183a5c0b87e6a4d101c70bd32c1c79",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/verity/fsverity_private.h",
            "fs/verity/open.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.11",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfsverity: RCU-delay the freeing of struct fsverity_info\n\n__fsverity_get_info() calls rhashtable_lookup_fast(), which just uses\nrcu_read_lock() and doesn\u0027t directly synchronize with\nfsverity_remove_info().\n\nFor the same inode this isn\u0027t a problem: its fsverity_info is removed\nonly at inode eviction time or upon failure to enable verity, when the\ninode no longer needs its fsverity_info and it will no longer be\naccessed via that inode.\n\nHowever, this is broken and can cause a use-after-free for concurrent\n__fsverity_get_info() for *different* inodes.  Those rely on following\nfsverity_info::rhash_head in the rhashtable under rcu_read_lock() only.\nThey also use fsverity_info::inode to do the key comparison.\n\nFix this by RCU-delaying the freeing of \u0027struct fsverity_info\u0027 after\nit\u0027s been removed from the rhashtable."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - `ioctl(FS_IOC_MEASURE_VERITY)` reaches `fsverity_ioctl_measure()` and `fsverity_get_info()`, while `unlinkat()`/`close()` of another fs-verity file reaches `clear_inode()`, `fsverity_cleanup_inode()`, and patched `fsverity_remove_info()`; these are local syscall paths, not wire data.\nAC:L - An attacker can enable many owned files to populate colliding rhashtable chains, then loop measurements of one inode while concurrently unlinking and closing the others; the attacker controls both lookup and freeing and can repeat the race.\nPR:L - `fsverity_ioctl_enable()` checks only `file_permission(filp, MAY_WRITE)`, `FMODE_READ`, and a writable mount, with no capability check; lookup and eviction require only ordinary access to attacker-owned files on btrfs or verity-enabled ext4/f2fs.\nUI:N - The attacker can create, enable, measure, unlink, and close all participating files using their own processes, without another user mounting media or taking any action.\nS:U - The dangling object belongs to the host kernel\u0027s `fsverity_info_hash` and `fsverity_info_cachep`; corrupting it affects the same kernel security authority and crosses no VM, IOMMU, or hypervisor boundary.\nC:H - `fsverity_remove_info()` frees the slab while `__rhashtable_lookup()` still reads `inode` and `rhash_head.next`; after cache reuse, a misdirected lookup is consumed by `fsverity_ioctl_measure()`, which dereferences `tree_params` and copies `file_digest` to userspace.\nI:H - File-read consumers pass the lookup result to `fsverity_verify_blocks()`, whose `clear_bit()` and `set_bit()` write through `vi-\u003ehash_block_verified`; attacker-groomed reuse of the freed object can therefore turn the UAF into arbitrary kernel-memory corruption.\nA:H - `kmem_cache_free()` permits allocator metadata to replace the freed `rhash_head.next` while the rhashtable loop still follows `pos-\u003enext`, which can oops or panic the kernel; repeated measure-and-evict cycles can retrigger it."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:10:12.469Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/fa84f091a8e7fc46fd29834496fab9739dd4c8dc"
        },
        {
          "url": "https://git.kernel.org/stable/c/e58c3805ed325fe2d4ae2dd467c0486cc860b733"
        }
      ],
      "title": "fsverity: RCU-delay the freeing of struct fsverity_info",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99051",
    "datePublished": "2026-10-23T12:22:30.370Z",
    "dateReserved": "2026-09-25T10:25:14.388Z",
    "dateUpdated": "2026-10-24T14:10:12.469Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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