fs/proc/task_mmu: check p->vec_buf for NULL

{
  "id": "539f242dbd9aa48d7b42cc08cb6a8e533d56a24ca301569d8084541382ede441",
  "url": "https://osv.dev/vulnerability/CVE-2025-40009",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "fs/proc/task_mmu: check p->vec_buf for NULL",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: fs/proc/task_mmu: check p->vec_buf for NULL When the PAGEMAP_SCAN ioctl is invoked with vec_len = 0 reaches pagemap_scan_backout_range(), kernel panics with null-ptr-deref: [ 44.936808] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 44.937797] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] [ 44.938391] CPU: 1 UID: 0 PID: 2480 Comm: reproducer Not tainted 6.17.0-rc6 #22 PREEMPT(none) [ 44.939062] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 44.939935] RIP: 0010:pagemap_scan_thp_entry.isra.0+0x741/0xa80 [ 44.946828] Call Trace: [ 44.947030] [ 44.949219] pagemap_scan_pmd_entry+0xec/0xfa0 [ 44.952593] walk_pmd_range.isra.0+0x302/0x910 [ 44.954069] walk_pud_range.isra.0+0x419/0x790 [ 44.954427] walk_p4d_range+0x41e/0x620 [ 44.954743] walk_pgd_range+0x31e/0x630 [ 44.955057] __walk_page_range+0x160/0x670 [ 44.956883] walk_page_range_mm+0x408/0x980 [ 44.958677] walk_page_range+0x66/0x90 [ 44.958984] do_pagemap_scan+0x28d/0x9c0 [ 44.961833] do_pagemap_cmd+0x59/0x80 [ 44.962484] __x64_sys_ioctl+0x18d/0x210 [ 44.962804] do_syscall_64+0x5b/0x290 [ 44.963111] entry_SYSCALL_64_after_hwframe+0x76/0x7e vec_len = 0 in pagemap_scan_init_bounce_buffer() means no buffers are allocated and p->vec_buf remains set to NULL. This breaks an assumption made ",
    "evidence": "osv:CVE-2025-40009",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.50",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.16.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-40009",
      "aliases": [
        "CVE-2025-40009"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "52526ca7fdb905a768a93f8faa418e9b988fc34b"
                },
                {
                  "fixed": "ca988dcdc6683ecd9de5f525ce469588a9141c21"
                },
                {
                  "fixed": "a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3"
                },
                {
                  "fixed": "28aa29986dde79e8466bc87569141291053833f5"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40009.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.50"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.16.10"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40009.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:38.093935131Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/28aa29986dde79e8466bc87569141291053833f5",
        "https://git.kernel.org/stable/c/a2cb8818a3d915cd33a1e8b2babc1bb0c34862c3",
        "https://git.kernel.org/stable/c/ca988dcdc6683ecd9de5f525ce469588a9141c21",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40009.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-40009",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40009.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-40009",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 505446,
  "published_at": "2025-10-20T15:26:55.208+00:00"
}