{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-64419",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-64419"
  ],
  "published": "2026-07-25T08:51:45Z",
  "summary": "mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()",
  "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 ->count_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 ->scan_objects()\ncallback with no RCU section.\n\nDrop the rcu_read_lock()/rcu_read_unlock().",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.178",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-64419"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/de5f69b8dae8698ac5e48dfcd30017887cdf4e5a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e441cbfbd0eaa6404278e985033c33caba4db767"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2fed79f0fe8c8d28a972c290dbfd693c3546c8c4"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/560e21e8ccff813e84d05f6500907c549a3d6985"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/86237e56091e70f09c0fbf217f9d9c0e08f556c4"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b902890c62d200b3509cb5e09cf1e0a66553c128"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-17T05:24:08Z"
  }
}