Vulnerability-Lookup

CVE-2026-64419 (GCVE-0-2026-64419)

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

Title

mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()

Summary

In the Linux kernel, the following vulnerability has been resolved: mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show() Reading the debugfs "count" file of a memcg-aware shrinker can sleep inside an RCU read-side critical section: BUG: sleeping function called from invalid context at kernel/cgroup/rstat.c:421 RCU nest depth: 1, expected: 0 css_rstat_flush mem_cgroup_flush_stats zswap_shrinker_count shrinker_debugfs_count_show shrinker_debugfs_count_show() invokes the ->count_objects() callback under rcu_read_lock(). The zswap callback flushes memcg stats via css_rstat_flush(), which may sleep, so it must not run under RCU. The RCU lock is not needed here. mem_cgroup_iter() takes RCU internally and returns a memcg holding a css reference (dropped on the next iteration or by mem_cgroup_iter_break()), so the memcg stays alive without it. The shrinker is kept alive by the open debugfs file: shrinker_free() removes the debugfs entries via debugfs_remove_recursive(), which waits for in-flight readers to drain, before call_rcu(..., shrinker_free_rcu_cb). The sibling "scan" handler already invokes the sleeping ->scan_objects() callback with no RCU section. Drop the rcu_read_lock()/rcu_read_unlock().

Severity

No CVSS data available.

Assigner

Linux

References

6 references

URL	Tags
https://git.kernel.org/stable/c/de5f69b8dae8698ac…
https://git.kernel.org/stable/c/e441cbfbd0eaa6404…
https://git.kernel.org/stable/c/2fed79f0fe8c8d28a…
https://git.kernel.org/stable/c/560e21e8ccff813e8…
https://git.kernel.org/stable/c/86237e56091e70f09…
https://git.kernel.org/stable/c/b902890c62d200b35…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < de5f69b8dae8698ac5e48dfcd30017887cdf4e5a (git) Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < e441cbfbd0eaa6404278e985033c33caba4db767 (git) Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < 2fed79f0fe8c8d28a972c290dbfd693c3546c8c4 (git) Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < 560e21e8ccff813e84d05f6500907c549a3d6985 (git) Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < 86237e56091e70f09c0fbf217f9d9c0e08f556c4 (git) Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < b902890c62d200b3509cb5e09cf1e0a66553c128 (git)
Linux	Linux	Affected: 6.0 Unaffected: 0 , < 6.0 (semver) Unaffected: 6.1.178 , ≤ 6.1.* (semver) Unaffected: 6.6.145 , ≤ 6.6.* (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-rc1 , ≤ * (original_commit_for_fix)

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JSON

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        }
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          "url": "https://git.kernel.org/stable/c/e441cbfbd0eaa6404278e985033c33caba4db767"
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          "url": "https://git.kernel.org/stable/c/2fed79f0fe8c8d28a972c290dbfd693c3546c8c4"
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        {
          "url": "https://git.kernel.org/stable/c/b902890c62d200b3509cb5e09cf1e0a66553c128"
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    "datePublished": "2026-07-25T08:50:58.342Z",
    "dateReserved": "2026-07-19T15:36:31.786Z",
    "dateUpdated": "2026-07-25T08:50:58.342Z",
    "state": "PUBLISHED"
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  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-64419",
      "date": "2026-07-26",
      "epss": "0.00173",
      "percentile": "0.06936"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64419\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-25T10:17:25.847\",\"lastModified\":\"2026-07-25T10:17:25.847\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()\\n\\nReading the debugfs \\\"count\\\" file of a memcg-aware shrinker can sleep\\ninside an RCU read-side critical section:\\n\\n  BUG: sleeping function called from invalid context at kernel/cgroup/rstat.c:421\\n  RCU nest depth: 1, expected: 0\\n   css_rstat_flush\\n   mem_cgroup_flush_stats\\n   zswap_shrinker_count\\n   shrinker_debugfs_count_show\\n\\nshrinker_debugfs_count_show() invokes the -\u003ecount_objects() callback under\\nrcu_read_lock().  The zswap callback flushes memcg stats via\\ncss_rstat_flush(), which may sleep, so it must not run under RCU.\\n\\nThe RCU lock is not needed here.  mem_cgroup_iter() takes RCU internally\\nand returns a memcg holding a css reference (dropped on the next iteration\\nor by mem_cgroup_iter_break()), so the memcg stays alive without it.  The\\nshrinker is kept alive by the open debugfs file: shrinker_free() removes\\nthe debugfs entries via debugfs_remove_recursive(), which waits for\\nin-flight readers to drain, before call_rcu(..., shrinker_free_rcu_cb). \\nThe sibling \\\"scan\\\" handler already invokes the sleeping -\u003escan_objects()\\ncallback with no RCU section.\\n\\nDrop the rcu_read_lock()/rcu_read_unlock().\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"mm/shrinker_debug.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5035ebc644aec92d55d1bbfe042f35341e4bffb5\",\"lessThan\":\"de5f69b8dae8698ac5e48dfcd30017887cdf4e5a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5035ebc644aec92d55d1bbfe042f35341e4bffb5\",\"lessThan\":\"e441cbfbd0eaa6404278e985033c33caba4db767\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5035ebc644aec92d55d1bbfe042f35341e4bffb5\",\"lessThan\":\"2fed79f0fe8c8d28a972c290dbfd693c3546c8c4\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5035ebc644aec92d55d1bbfe042f35341e4bffb5\",\"lessThan\":\"560e21e8ccff813e84d05f6500907c549a3d6985\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5035ebc644aec92d55d1bbfe042f35341e4bffb5\",\"lessThan\":\"86237e56091e70f09c0fbf217f9d9c0e08f556c4\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5035ebc644aec92d55d1bbfe042f35341e4bffb5\",\"lessThan\":\"b902890c62d200b3509cb5e09cf1e0a66553c128\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"mm/shrinker_debug.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.0\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.0\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.178\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.96\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.39\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.4\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/2fed79f0fe8c8d28a972c290dbfd693c3546c8c4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/560e21e8ccff813e84d05f6500907c549a3d6985\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/86237e56091e70f09c0fbf217f9d9c0e08f556c4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b902890c62d200b3509cb5e09cf1e0a66553c128\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/de5f69b8dae8698ac5e48dfcd30017887cdf4e5a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e441cbfbd0eaa6404278e985033c33caba4db767\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "suse_vex": {
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      "current_release_date": "2026-07-25T15:59:42Z",
      "cve": "CVE-2026-64419",
      "id": "CVE-2026-64419",
      "initial_release_date": "2026-07-25T15:59:42Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64419",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64419.json",
      "version": "2"
    }
  }
}

GHSA-H85J-5G9P-PPJ5

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-25 12:31

Details

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

mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()

Reading the debugfs "count" file of a memcg-aware shrinker can sleep inside an RCU read-side critical section:

BUG: sleeping function called from invalid context at kernel/cgroup/rstat.c:421 RCU nest depth: 1, expected: 0 css_rstat_flush mem_cgroup_flush_stats zswap_shrinker_count shrinker_debugfs_count_show

shrinker_debugfs_count_show() invokes the ->count_objects() callback under rcu_read_lock(). The zswap callback flushes memcg stats via css_rstat_flush(), which may sleep, so it must not run under RCU.

The RCU lock is not needed here. mem_cgroup_iter() takes RCU internally and returns a memcg holding a css reference (dropped on the next iteration or by mem_cgroup_iter_break()), so the memcg stays alive without it. The shrinker is kept alive by the open debugfs file: shrinker_free() removes the debugfs entries via debugfs_remove_recursive(), which waits for in-flight readers to drain, before call_rcu(..., shrinker_free_rcu_cb). The sibling "scan" handler already invokes the sleeping ->scan_objects() callback with no RCU section.

Drop the rcu_read_lock()/rcu_read_unlock().

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-64419"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:25Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()\n\nReading the debugfs \"count\" file of a memcg-aware shrinker can sleep\ninside an RCU read-side critical section:\n\n  BUG: sleeping function called from invalid context at kernel/cgroup/rstat.c:421\n  RCU nest depth: 1, expected: 0\n   css_rstat_flush\n   mem_cgroup_flush_stats\n   zswap_shrinker_count\n   shrinker_debugfs_count_show\n\nshrinker_debugfs_count_show() invokes the -\u003ecount_objects() callback under\nrcu_read_lock().  The zswap callback flushes memcg stats via\ncss_rstat_flush(), which may sleep, so it must not run under RCU.\n\nThe RCU lock is not needed here.  mem_cgroup_iter() takes RCU internally\nand returns a memcg holding a css reference (dropped on the next iteration\nor by mem_cgroup_iter_break()), so the memcg stays alive without it.  The\nshrinker is kept alive by the open debugfs file: shrinker_free() removes\nthe debugfs entries via debugfs_remove_recursive(), which waits for\nin-flight readers to drain, before call_rcu(..., shrinker_free_rcu_cb). \nThe sibling \"scan\" handler already invokes the sleeping -\u003escan_objects()\ncallback with no RCU section.\n\nDrop the rcu_read_lock()/rcu_read_unlock().",
  "id": "GHSA-h85j-5g9p-ppj5",
  "modified": "2026-07-25T12:31:35Z",
  "published": "2026-07-25T12:31:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64419"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2fed79f0fe8c8d28a972c290dbfd693c3546c8c4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/560e21e8ccff813e84d05f6500907c549a3d6985"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/86237e56091e70f09c0fbf217f9d9c0e08f556c4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b902890c62d200b3509cb5e09cf1e0a66553c128"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de5f69b8dae8698ac5e48dfcd30017887cdf4e5a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e441cbfbd0eaa6404278e985033c33caba4db767"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

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

CVE-2026-64419 (GCVE-0-2026-64419)

GHSA-H85J-5G9P-PPJ5

Tags

Sightings

Nomenclature