Vulnerability-Lookup

FKIE_CVE-2026-64418

Vulnerability from fkie_nvd - Published: 2026-07-25 10:17 - Updated: 2026-07-27 05:16

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: mm: shrinker: fix shrinker_info teardown race with expansion expand_shrinker_info() iterates all visible memcgs under shrinker_mutex, including memcgs that have not finished ->css_online() yet. Once pn->shrinker_info has been published, teardown must stay serialized with expand_shrinker_info() until that memcg is either fully online or no longer visible to iteration. Today alloc_shrinker_info() breaks that rule by dropping shrinker_mutex before freeing a partially initialized shrinker_info array, which may cause the following race: CPU0 CPU1 ==== ==== css_create --> list_add_tail_rcu(&css->sibling, &parent_css->children); online_css --> mem_cgroup_css_online --> alloc_shrinker_info --> alloc node0 info rcu_assign_pointer(C->node0->shrinker_info, old0) alloc node1 info -> FAIL -> goto err mutex_unlock(shrinker_mutex) shrinker_alloc() --> shrinker_memcg_alloc --> mutex_lock(shrinker_mutex) expand_shrinker_info --> mem_cgroup_iter see the memcg expand_one_shrinker_info --> old0 = C->node0->shrinker_info memcpy(new->unit, old0->unit, ...); free_shrinker_info --> kvfree(old0); /* double free !! */ kvfree_rcu(old0, rcu); The same problem exists later in mem_cgroup_css_online(). If alloc_shrinker_info() succeeds but a subsequent objcg allocation fails, the free_objcg -> free_shrinker_info() unwind path tears down the already published pn->shrinker_info arrays without shrinker_mutex. The expand_one_shrinker_info() can race with that teardown in the same way, leading to use-after-free or double-free of the old shrinker_info. Fix this by serializing shrinker_info teardown with shrinker_mutex, and by keeping alloc_shrinker_info() error cleanup inside the locked section.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/284c267f013e45d8c89d9fb9373105dc8e6c0947
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/6465ff3ce65131c774a312d450abe10f4b9f3875
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/65476d31d8056e859c48580f82295ce159196ffe
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/b9a280a9a454ed514636351d53fe2a233dc5054b

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/shrinker.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b9a280a9a454ed514636351d53fe2a233dc5054b",
              "status": "affected",
              "version": "307bececcd1205bcb67a3c0d53a69db237ccc9d4",
              "versionType": "git"
            },
            {
              "lessThan": "6465ff3ce65131c774a312d450abe10f4b9f3875",
              "status": "affected",
              "version": "307bececcd1205bcb67a3c0d53a69db237ccc9d4",
              "versionType": "git"
            },
            {
              "lessThan": "284c267f013e45d8c89d9fb9373105dc8e6c0947",
              "status": "affected",
              "version": "307bececcd1205bcb67a3c0d53a69db237ccc9d4",
              "versionType": "git"
            },
            {
              "lessThan": "65476d31d8056e859c48580f82295ce159196ffe",
              "status": "affected",
              "version": "307bececcd1205bcb67a3c0d53a69db237ccc9d4",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/shrinker.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
            {
              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: shrinker: fix shrinker_info teardown race with expansion\n\nexpand_shrinker_info() iterates all visible memcgs under shrinker_mutex,\nincluding memcgs that have not finished -\u003ecss_online() yet.\n\nOnce pn-\u003eshrinker_info has been published, teardown must stay serialized\nwith expand_shrinker_info() until that memcg is either fully online or no\nlonger visible to iteration.  Today alloc_shrinker_info() breaks that rule\nby dropping shrinker_mutex before freeing a partially initialized\nshrinker_info array, which may cause the following race:\n\nCPU0                   CPU1\n====                   ====\n\ncss_create\n--\u003e list_add_tail_rcu(\u0026css-\u003esibling, \u0026parent_css-\u003echildren);\n    online_css\n    --\u003e mem_cgroup_css_online\n        --\u003e alloc_shrinker_info\n            --\u003e alloc node0 info\n                rcu_assign_pointer(C-\u003enode0-\u003eshrinker_info, old0)\n                alloc node1 info -\u003e FAIL -\u003e goto err\n                mutex_unlock(shrinker_mutex)\n\n                       shrinker_alloc()\n                       --\u003e shrinker_memcg_alloc\n                           --\u003e mutex_lock(shrinker_mutex)\n                               expand_shrinker_info\n                               --\u003e mem_cgroup_iter see the memcg\n                                   expand_one_shrinker_info\n                                   --\u003e old0 = C-\u003enode0-\u003eshrinker_info\n                                       memcpy(new-\u003eunit, old0-\u003eunit, ...);\n\n                free_shrinker_info\n                --\u003e kvfree(old0);\n\n                                       /* double free !! */\n                                       kvfree_rcu(old0, rcu);\n\nThe same problem exists later in mem_cgroup_css_online().  If\nalloc_shrinker_info() succeeds but a subsequent objcg allocation fails,\nthe free_objcg -\u003e free_shrinker_info() unwind path tears down the already\npublished pn-\u003eshrinker_info arrays without shrinker_mutex.  The\nexpand_one_shrinker_info() can race with that teardown in the same way,\nleading to use-after-free or double-free of the old shrinker_info.\n\nFix this by serializing shrinker_info teardown with shrinker_mutex, and by\nkeeping alloc_shrinker_info() error cleanup inside the locked section."
    }
  ],
  "id": "CVE-2026-64418",
  "lastModified": "2026-07-27T05:16:48.697",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-25T10:17:25.727",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/284c267f013e45d8c89d9fb9373105dc8e6c0947"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6465ff3ce65131c774a312d450abe10f4b9f3875"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/65476d31d8056e859c48580f82295ce159196ffe"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b9a280a9a454ed514636351d53fe2a233dc5054b"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-64418 (GCVE-0-2026-64418)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:50 – Updated: 2026-08-05 12:41

Title

mm: shrinker: fix shrinker_info teardown race with expansion

Summary

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

References

4 references

URL	Tags
https://git.kernel.org/stable/c/b9a280a9a454ed514…
https://git.kernel.org/stable/c/6465ff3ce65131c77…
https://git.kernel.org/stable/c/284c267f013e45d8c…
https://git.kernel.org/stable/c/65476d31d8056e859…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 307bececcd1205bcb67a3c0d53a69db237ccc9d4 , < b9a280a9a454ed514636351d53fe2a233dc5054b (git) Affected: 307bececcd1205bcb67a3c0d53a69db237ccc9d4 , < 6465ff3ce65131c774a312d450abe10f4b9f3875 (git) Affected: 307bececcd1205bcb67a3c0d53a69db237ccc9d4 , < 284c267f013e45d8c89d9fb9373105dc8e6c0947 (git) Affected: 307bececcd1205bcb67a3c0d53a69db237ccc9d4 , < 65476d31d8056e859c48580f82295ce159196ffe (git)
Linux	Linux	Affected: 6.7 Unaffected: 0 , < 6.7 (semver) Unaffected: 6.12.96 , ≤ 6.12.* (semver) Unaffected: 6.18.39 , ≤ 6.18.* (semver) Unaffected: 7.1.4 , ≤ 7.1.* (semver) Unaffected: 7.2-rc3 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/shrinker.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b9a280a9a454ed514636351d53fe2a233dc5054b",
              "status": "affected",
              "version": "307bececcd1205bcb67a3c0d53a69db237ccc9d4",
              "versionType": "git"
            },
            {
              "lessThan": "6465ff3ce65131c774a312d450abe10f4b9f3875",
              "status": "affected",
              "version": "307bececcd1205bcb67a3c0d53a69db237ccc9d4",
              "versionType": "git"
            },
            {
              "lessThan": "284c267f013e45d8c89d9fb9373105dc8e6c0947",
              "status": "affected",
              "version": "307bececcd1205bcb67a3c0d53a69db237ccc9d4",
              "versionType": "git"
            },
            {
              "lessThan": "65476d31d8056e859c48580f82295ce159196ffe",
              "status": "affected",
              "version": "307bececcd1205bcb67a3c0d53a69db237ccc9d4",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/shrinker.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
            {
              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.96",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.39",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.4",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2-rc3",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: shrinker: fix shrinker_info teardown race with expansion\n\nexpand_shrinker_info() iterates all visible memcgs under shrinker_mutex,\nincluding memcgs that have not finished -\u003ecss_online() yet.\n\nOnce pn-\u003eshrinker_info has been published, teardown must stay serialized\nwith expand_shrinker_info() until that memcg is either fully online or no\nlonger visible to iteration.  Today alloc_shrinker_info() breaks that rule\nby dropping shrinker_mutex before freeing a partially initialized\nshrinker_info array, which may cause the following race:\n\nCPU0                   CPU1\n====                   ====\n\ncss_create\n--\u003e list_add_tail_rcu(\u0026css-\u003esibling, \u0026parent_css-\u003echildren);\n    online_css\n    --\u003e mem_cgroup_css_online\n        --\u003e alloc_shrinker_info\n            --\u003e alloc node0 info\n                rcu_assign_pointer(C-\u003enode0-\u003eshrinker_info, old0)\n                alloc node1 info -\u003e FAIL -\u003e goto err\n                mutex_unlock(shrinker_mutex)\n\n                       shrinker_alloc()\n                       --\u003e shrinker_memcg_alloc\n                           --\u003e mutex_lock(shrinker_mutex)\n                               expand_shrinker_info\n                               --\u003e mem_cgroup_iter see the memcg\n                                   expand_one_shrinker_info\n                                   --\u003e old0 = C-\u003enode0-\u003eshrinker_info\n                                       memcpy(new-\u003eunit, old0-\u003eunit, ...);\n\n                free_shrinker_info\n                --\u003e kvfree(old0);\n\n                                       /* double free !! */\n                                       kvfree_rcu(old0, rcu);\n\nThe same problem exists later in mem_cgroup_css_online().  If\nalloc_shrinker_info() succeeds but a subsequent objcg allocation fails,\nthe free_objcg -\u003e free_shrinker_info() unwind path tears down the already\npublished pn-\u003eshrinker_info arrays without shrinker_mutex.  The\nexpand_one_shrinker_info() can race with that teardown in the same way,\nleading to use-after-free or double-free of the old shrinker_info.\n\nFix this by serializing shrinker_info teardown with shrinker_mutex, and by\nkeeping alloc_shrinker_info() error cleanup inside the locked section."
        }
      ],
      "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 - The vulnerable path is reachable through local cgroup mkdir operations raced against memcg-aware shrinker allocation, such as mounting new tmpfs instances.\nAC:L - An attacker can repeatedly create cgroups, induce allocation pressure, and concurrently allocate shrinkers, controlling both sides of the race and widening it through repetition.\nPR:L - An unprivileged user with a delegated cgroup v2 subtree can create memory cgroups, while user namespaces provide the capability needed to mount user-namespace-enabled filesystems.\nUI:N - Exploitation requires no action by another user once the attacker can execute the concurrent local operations.\nS:U - The corruption occurs within the kernel and represents ordinary local privilege escalation within the same security authority.\nC:H - The use-after-free and delayed double-free permit heap reuse and manipulation of dangling shrinker unit pointers, potentially enabling arbitrary kernel-memory disclosure.\nI:H - The dangling pointers, atomic operations on freed units, and double-free can provide arbitrary kernel-memory corruption and control-flow hijacking.\nA:H - The use-after-free or double-free can directly cause a kernel oops, panic, or other system-wide failure."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:41:50.196Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b9a280a9a454ed514636351d53fe2a233dc5054b"
        },
        {
          "url": "https://git.kernel.org/stable/c/6465ff3ce65131c774a312d450abe10f4b9f3875"
        },
        {
          "url": "https://git.kernel.org/stable/c/284c267f013e45d8c89d9fb9373105dc8e6c0947"
        },
        {
          "url": "https://git.kernel.org/stable/c/65476d31d8056e859c48580f82295ce159196ffe"
        }
      ],
      "title": "mm: shrinker: fix shrinker_info teardown race with expansion",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64418",
    "datePublished": "2026-07-25T08:50:57.594Z",
    "dateReserved": "2026-07-19T15:36:31.786Z",
    "dateUpdated": "2026-08-05T12:41:50.196Z",
    "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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

FKIE_CVE-2026-64418

CVE-2026-64418 (GCVE-0-2026-64418)

Tags

Sightings

Nomenclature