{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-64417",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-64417"
  ],
  "published": "2026-07-25T08:51:45Z",
  "summary": "mm: shrinker: fix NULL pointer dereference in debugfs",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: shrinker: fix NULL pointer dereference in debugfs\n\nshrinker_debugfs_add() creates both \"count\" and \"scan\" debugfs files\nunconditionally.\n\nThat assumes every shrinker implements both count_objects() and\nscan_objects(), which is not guaranteed.  For example, the xen-backend\nshrinker sets count_objects() but leaves scan_objects() NULL, so writing\nto its scan file calls through a NULL function pointer and panics the\nkernel:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nRIP: 0010:0x0\nCode: Unable to access opcode bytes at 0xffffffffffffffd6.\nCall Trace:\n <TASK>\n shrinker_debugfs_scan_write+0x12e/0x270\n full_proxy_write+0x5f/0x90\n vfs_write+0xde/0x420\n ? filp_flush+0x75/0x90\n ? filp_close+0x1d/0x30\n ? do_dup2+0xb8/0x120\n ksys_write+0x68/0xf0\n ? filp_flush+0x75/0x90\n do_syscall_64+0xb3/0x5b0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThe count path has the same issue in principle if a shrinker omits\ncount_objects().\n\nTo fix it, only create \"count\" and \"scan\" debugfs files when the\ncorresponding callbacks are present.",
  "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-2026-64417"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ebb45c2648b1f60715fd283700f651e05e431231"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/09d2407985b8ce3e831f9d4310fe7ac06a6b3ae9"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/36f8534f461222291a74156ab91f3ba9f09b6f93"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/006467ab932698612398f853344a7405164541f4"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b9beed2322f3538b0d2d53307062da4102b8d8d8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e30453c61e185e914fde83c650e268067b140218"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-17T05:24:08Z"
  }
}