blk-throttle: fix access race during throttle policy activation

{
  "id": "c700a13ac7045e042d5c055e15b2382a377c1ee62d94c994620f8af5d3fdf376",
  "url": "https://osv.dev/vulnerability/CVE-2025-40147",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "blk-throttle: fix access race during throttle policy activation",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: blk-throttle: fix access race during throttle policy activation On repeated cold boots we occasionally hit a NULL pointer crash in blk_should_throtl() when throttling is consulted before the throttle policy is fully enabled for the queue. Checking only q->td != NULL is insufficient during early initialization, so blkg_to_pd() for the throttle policy can still return NULL and blkg_to_tg() becomes NULL, which later gets dereferenced. Unable to handle kernel NULL pointer dereference at virtual address 0000000000000156 ... pc : submit_bio_noacct+0x14c/0x4c8 lr : submit_bio_noacct+0x48/0x4c8 sp : ffff800087f0b690 x29: ffff800087f0b690 x28: 0000000000005f90 x27: ffff00068af393c0 x26: 0000000000080000 x25: 000000000002fbc0 x24: ffff000684ddcc70 x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000 x20: 0000000000080000 x19: ffff000684ddcd08 x18: ffffffffffffffff x17: 0000000000000000 x16: ffff80008132a550 x15: 0000ffff98020fff x14: 0000000000000000 x13: 1fffe000d11d7021 x12: ffff000688eb810c x11: ffff00077ec4bb80 x10: ffff000688dcb720 x9 : ffff80008068ef60 x8 : 00000a6fb8a86e85 x7 : 000000000000111e x6 : 0000000000000002 x5 : 0000000000000246 x4 : 0000000000015cff x3 : 0000000000394500 x2 : ffff000682e35e40 x1 : 0000000000364940 x0 : 000000000000001a Call trace: submit_bio_noacct+0x14c/0x4c8 verity_map+0x178/0x2c8 __map_bio+0x228/0x250 dm_submit_bio+0x1c4/0x678 __submit_bio+0x170/0x230 submit_bio_noacct_",
    "evidence": "osv:CVE-2025-40147",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.78",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.17.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-40147",
      "aliases": [
        "CVE-2025-40147"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "a3166c51702bb00b8f8b84022090cbab8f37be1a"
                },
                {
                  "fixed": "7b4bfd02c934dbbb18814ed012ecb90b58db6935"
                },
                {
                  "fixed": "6a0c394300a7b0c05504596685de8a46707171fc"
                },
                {
                  "fixed": "bd9fd5be6bc0836820500f68fff144609fbd85a9"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40147.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.10.0"
                },
                {
                  "fixed": "6.12.78"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.17.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40147.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:33.795403197Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/6a0c394300a7b0c05504596685de8a46707171fc",
        "https://git.kernel.org/stable/c/7b4bfd02c934dbbb18814ed012ecb90b58db6935",
        "https://git.kernel.org/stable/c/bd9fd5be6bc0836820500f68fff144609fbd85a9",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40147.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-40147",
        "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-2025-40147.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-40147",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 501110,
  "published_at": "2025-11-12T10:23:26.556+00:00"
}