CVE-2025-37856 (GCVE-0-2025-37856)
Vulnerability from cvelistv5
Published
2025-05-09 06:42
Modified
2025-05-26 05:22
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at all of racing with mark_bg_unused(), or a different future user of bg_list, better to be safe than sorry. Otherwise we risk the following interleaving (bg_list refcount in parens) T1 (some random op) T2 (btrfs_mark_bg_unused) !list_empty(&bg->bg_list); (1) list_del_init(&bg->bg_list); (1) list_move_tail (1) btrfs_put_block_group (0) btrfs_delete_unused_bgs bg = list_first_entry list_del_init(&bg->bg_list); btrfs_put_block_group(bg); (-1) Ultimately, this results in a broken ref count that hits zero one deref early and the real final deref underflows the refcount, resulting in a WARNING.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/extent-tree.c",
            "fs/btrfs/transaction.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "bf089c4d1141b27332c092b1dcca5022c415a3b6",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "909e60fb469d4101c6b08cf6e622efb062bb24a1",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "185fd73e5ac06027c4be9a129e59193f6a3ef202",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "7511e29cf1355b2c47d0effb39e463119913e2f6",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/extent-tree.c",
            "fs/btrfs/transaction.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.24",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.13.*",
              "status": "unaffected",
              "version": "6.13.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.14.*",
              "status": "unaffected",
              "version": "6.14.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.15",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.24",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.14.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: harden block_group::bg_list against list_del() races\n\nAs far as I can tell, these calls of list_del_init() on bg_list cannot\nrun concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(),\nas they are in transaction error paths and situations where the block\ngroup is readonly.\n\nHowever, if there is any chance at all of racing with mark_bg_unused(),\nor a different future user of bg_list, better to be safe than sorry.\n\nOtherwise we risk the following interleaving (bg_list refcount in parens)\n\nT1 (some random op)                       T2 (btrfs_mark_bg_unused)\n                                        !list_empty(\u0026bg-\u003ebg_list); (1)\nlist_del_init(\u0026bg-\u003ebg_list); (1)\n                                        list_move_tail (1)\nbtrfs_put_block_group (0)\n                                        btrfs_delete_unused_bgs\n                                             bg = list_first_entry\n                                             list_del_init(\u0026bg-\u003ebg_list);\n                                             btrfs_put_block_group(bg); (-1)\n\nUltimately, this results in a broken ref count that hits zero one deref\nearly and the real final deref underflows the refcount, resulting in a WARNING."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-26T05:22:23.651Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/bf089c4d1141b27332c092b1dcca5022c415a3b6"
        },
        {
          "url": "https://git.kernel.org/stable/c/909e60fb469d4101c6b08cf6e622efb062bb24a1"
        },
        {
          "url": "https://git.kernel.org/stable/c/185fd73e5ac06027c4be9a129e59193f6a3ef202"
        },
        {
          "url": "https://git.kernel.org/stable/c/7511e29cf1355b2c47d0effb39e463119913e2f6"
        }
      ],
      "title": "btrfs: harden block_group::bg_list against list_del() races",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-37856",
    "datePublished": "2025-05-09T06:42:04.315Z",
    "dateReserved": "2025-04-16T04:51:23.956Z",
    "dateUpdated": "2025-05-26T05:22:23.651Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-37856\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-05-09T07:16:06.593\",\"lastModified\":\"2025-05-12T17:32:52.810\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbtrfs: harden block_group::bg_list against list_del() races\\n\\nAs far as I can tell, these calls of list_del_init() on bg_list cannot\\nrun concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(),\\nas they are in transaction error paths and situations where the block\\ngroup is readonly.\\n\\nHowever, if there is any chance at all of racing with mark_bg_unused(),\\nor a different future user of bg_list, better to be safe than sorry.\\n\\nOtherwise we risk the following interleaving (bg_list refcount in parens)\\n\\nT1 (some random op)                       T2 (btrfs_mark_bg_unused)\\n                                        !list_empty(\u0026bg-\u003ebg_list); (1)\\nlist_del_init(\u0026bg-\u003ebg_list); (1)\\n                                        list_move_tail (1)\\nbtrfs_put_block_group (0)\\n                                        btrfs_delete_unused_bgs\\n                                             bg = list_first_entry\\n                                             list_del_init(\u0026bg-\u003ebg_list);\\n                                             btrfs_put_block_group(bg); (-1)\\n\\nUltimately, this results in a broken ref count that hits zero one deref\\nearly and the real final deref underflows the refcount, resulting in a WARNING.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: btrfs: endurecer block_group::bg_list contra ejecuciones list_del() Hasta donde puedo decir, estas llamadas de list_del_init() en bg_list no se pueden ejecutar simult\u00e1neamente con btrfs_mark_bg_unused() o btrfs_mark_bg_to_reclaim(), ya que est\u00e1n en rutas de error de transacci\u00f3n y situaciones en las que el grupo de bloques es de solo lectura. Sin embargo, si hay alguna posibilidad de competir con mark_bg_unused(), o con un futuro usuario diferente de bg_list, m\u00e1s vale prevenir que curar. De lo contrario, nos arriesgamos al siguiente intercalado (bg_list refcount entre par\u00e9ntesis) T1 (alguna operaci\u00f3n aleatoria) T2 (btrfs_mark_bg_unused) !list_empty(\u0026amp;bg-\u0026gt;bg_list); (1) list_del_init(\u0026amp;bg-\u0026gt;bg_list); (1) list_move_tail (1) btrfs_put_block_group (0) btrfs_delete_unused_bgs bg = list_first_entry list_del_init(\u0026amp;bg-\u0026gt;bg_list); btrfs_put_block_group(bg); (-1) En \u00faltima instancia, esto da como resultado un recuento de referencias roto que llega a cero un deref antes y el deref final real desborda el recuento de referencias, lo que genera una ADVERTENCIA.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/185fd73e5ac06027c4be9a129e59193f6a3ef202\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/7511e29cf1355b2c47d0effb39e463119913e2f6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/909e60fb469d4101c6b08cf6e622efb062bb24a1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bf089c4d1141b27332c092b1dcca5022c415a3b6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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