CVE-2026-64419 (GCVE-0-2026-64419)
Vulnerability from cvelistv5
Published
2026-07-25 08:50
Modified
2026-08-17 04:55
Severity ?
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().
References
Impacted products
Vendor Product Version
Linux Linux Version: 5035ebc644aec92d55d1bbfe042f35341e4bffb5
Version: 5035ebc644aec92d55d1bbfe042f35341e4bffb5
Version: 5035ebc644aec92d55d1bbfe042f35341e4bffb5
Version: 5035ebc644aec92d55d1bbfe042f35341e4bffb5
Version: 5035ebc644aec92d55d1bbfe042f35341e4bffb5
Version: 5035ebc644aec92d55d1bbfe042f35341e4bffb5
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{
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          "programFiles": [
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      "cpeApplicability": [
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          "nodes": [
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      "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()."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:55:18.870Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/de5f69b8dae8698ac5e48dfcd30017887cdf4e5a"
        },
        {
          "url": "https://git.kernel.org/stable/c/e441cbfbd0eaa6404278e985033c33caba4db767"
        },
        {
          "url": "https://git.kernel.org/stable/c/2fed79f0fe8c8d28a972c290dbfd693c3546c8c4"
        },
        {
          "url": "https://git.kernel.org/stable/c/560e21e8ccff813e84d05f6500907c549a3d6985"
        },
        {
          "url": "https://git.kernel.org/stable/c/86237e56091e70f09c0fbf217f9d9c0e08f556c4"
        },
        {
          "url": "https://git.kernel.org/stable/c/b902890c62d200b3509cb5e09cf1e0a66553c128"
        }
      ],
      "title": "mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()",
      "x_generator": {
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64419",
    "datePublished": "2026-07-25T08:50:58.342Z",
    "dateReserved": "2026-07-19T15:36:31.786Z",
    "dateUpdated": "2026-08-17T04:55:18.870Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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