CVE-2025-21658 (GCVE-0-2025-21658)
Vulnerability from cvelistv5
Published
2025-01-21 12:18
Modified
2025-05-04 07:18
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: avoid NULL pointer dereference if no valid extent tree [BUG] Syzbot reported a crash with the following call trace: BTRFS info (device loop0): scrub: started on devid 1 BUG: kernel NULL pointer dereference, address: 0000000000000208 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: loaded Tainted: G O 6.13.0-rc4-custom+ #206 Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs] Call Trace: <TASK> scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs] scrub_simple_mirror+0x175/0x260 [btrfs] scrub_stripe+0x5d4/0x6c0 [btrfs] scrub_chunk+0xbb/0x170 [btrfs] scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs] btrfs_scrub_dev+0x240/0x600 [btrfs] btrfs_ioctl+0x1dc8/0x2fa0 [btrfs] ? do_sys_openat2+0xa5/0xf0 __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x4f/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> [CAUSE] The reproducer is using a corrupted image where extent tree root is corrupted, thus forcing to use "rescue=all,ro" mount option to mount the image. Then it triggered a scrub, but since scrub relies on extent tree to find where the data/metadata extents are, scrub_find_fill_first_stripe() relies on an non-empty extent root. But unfortunately scrub_find_fill_first_stripe() doesn't really expect an NULL pointer for extent root, it use extent_root to grab fs_info and triggered a NULL pointer dereference. [FIX] Add an extra check for a valid extent root at the beginning of scrub_find_fill_first_stripe(). The new error path is introduced by 42437a6386ff ("btrfs: introduce mount option rescue=ignorebadroots"), but that's pretty old, and later commit b979547513ff ("btrfs: scrub: introduce helper to find and fill sector info for a scrub_stripe") changed how we do scrub. So for kernels older than 6.6, the fix will need manual backport.
References
Impacted products
Vendor Product Version
Linux Linux Version: 42437a6386ffeaaf200731e73d723ea491f3fe7d
Version: 42437a6386ffeaaf200731e73d723ea491f3fe7d
Version: 42437a6386ffeaaf200731e73d723ea491f3fe7d
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/scrub.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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          "vendor": "Linux",
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            },
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              "lessThanOrEqual": "6.12.*",
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              "version": "6.12.10",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.13",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: avoid NULL pointer dereference if no valid extent tree\n\n[BUG]\nSyzbot reported a crash with the following call trace:\n\n  BTRFS info (device loop0): scrub: started on devid 1\n  BUG: kernel NULL pointer dereference, address: 0000000000000208\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0\n  Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI\n  CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: loaded Tainted: G           O       6.13.0-rc4-custom+ #206\n  Tainted: [O]=OOT_MODULE\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022\n  RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs]\n  Call Trace:\n   \u003cTASK\u003e\n   scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs]\n   scrub_simple_mirror+0x175/0x260 [btrfs]\n   scrub_stripe+0x5d4/0x6c0 [btrfs]\n   scrub_chunk+0xbb/0x170 [btrfs]\n   scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs]\n   btrfs_scrub_dev+0x240/0x600 [btrfs]\n   btrfs_ioctl+0x1dc8/0x2fa0 [btrfs]\n   ? do_sys_openat2+0xa5/0xf0\n   __x64_sys_ioctl+0x97/0xc0\n   do_syscall_64+0x4f/0x120\n   entry_SYSCALL_64_after_hwframe+0x76/0x7e\n   \u003c/TASK\u003e\n\n[CAUSE]\nThe reproducer is using a corrupted image where extent tree root is\ncorrupted, thus forcing to use \"rescue=all,ro\" mount option to mount the\nimage.\n\nThen it triggered a scrub, but since scrub relies on extent tree to find\nwhere the data/metadata extents are, scrub_find_fill_first_stripe()\nrelies on an non-empty extent root.\n\nBut unfortunately scrub_find_fill_first_stripe() doesn\u0027t really expect\nan NULL pointer for extent root, it use extent_root to grab fs_info and\ntriggered a NULL pointer dereference.\n\n[FIX]\nAdd an extra check for a valid extent root at the beginning of\nscrub_find_fill_first_stripe().\n\nThe new error path is introduced by 42437a6386ff (\"btrfs: introduce\nmount option rescue=ignorebadroots\"), but that\u0027s pretty old, and later\ncommit b979547513ff (\"btrfs: scrub: introduce helper to find and fill\nsector info for a scrub_stripe\") changed how we do scrub.\n\nSo for kernels older than 6.6, the fix will need manual backport."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-04T07:18:24.189Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/24b85a8b0310e0144da9ab30be42e87e6476638a"
        },
        {
          "url": "https://git.kernel.org/stable/c/aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784"
        },
        {
          "url": "https://git.kernel.org/stable/c/6aecd91a5c5b68939cf4169e32bc49f3cd2dd329"
        }
      ],
      "title": "btrfs: avoid NULL pointer dereference if no valid extent tree",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21658",
    "datePublished": "2025-01-21T12:18:14.578Z",
    "dateReserved": "2024-12-29T08:45:45.731Z",
    "dateUpdated": "2025-05-04T07:18:24.189Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-21658\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-01-21T13:15:09.437\",\"lastModified\":\"2025-01-22T23:02:59.383\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbtrfs: avoid NULL pointer dereference if no valid extent tree\\n\\n[BUG]\\nSyzbot reported a crash with the following call trace:\\n\\n  BTRFS info (device loop0): scrub: started on devid 1\\n  BUG: kernel NULL pointer dereference, address: 0000000000000208\\n  #PF: supervisor read access in kernel mode\\n  #PF: error_code(0x0000) - not-present page\\n  PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0\\n  Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI\\n  CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: loaded Tainted: G           O       6.13.0-rc4-custom+ #206\\n  Tainted: [O]=OOT_MODULE\\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022\\n  RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs]\\n  Call Trace:\\n   \u003cTASK\u003e\\n   scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs]\\n   scrub_simple_mirror+0x175/0x260 [btrfs]\\n   scrub_stripe+0x5d4/0x6c0 [btrfs]\\n   scrub_chunk+0xbb/0x170 [btrfs]\\n   scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs]\\n   btrfs_scrub_dev+0x240/0x600 [btrfs]\\n   btrfs_ioctl+0x1dc8/0x2fa0 [btrfs]\\n   ? do_sys_openat2+0xa5/0xf0\\n   __x64_sys_ioctl+0x97/0xc0\\n   do_syscall_64+0x4f/0x120\\n   entry_SYSCALL_64_after_hwframe+0x76/0x7e\\n   \u003c/TASK\u003e\\n\\n[CAUSE]\\nThe reproducer is using a corrupted image where extent tree root is\\ncorrupted, thus forcing to use \\\"rescue=all,ro\\\" mount option to mount the\\nimage.\\n\\nThen it triggered a scrub, but since scrub relies on extent tree to find\\nwhere the data/metadata extents are, scrub_find_fill_first_stripe()\\nrelies on an non-empty extent root.\\n\\nBut unfortunately scrub_find_fill_first_stripe() doesn\u0027t really expect\\nan NULL pointer for extent root, it use extent_root to grab fs_info and\\ntriggered a NULL pointer dereference.\\n\\n[FIX]\\nAdd an extra check for a valid extent root at the beginning of\\nscrub_find_fill_first_stripe().\\n\\nThe new error path is introduced by 42437a6386ff (\\\"btrfs: introduce\\nmount option rescue=ignorebadroots\\\"), but that\u0027s pretty old, and later\\ncommit b979547513ff (\\\"btrfs: scrub: introduce helper to find and fill\\nsector info for a scrub_stripe\\\") changed how we do scrub.\\n\\nSo for kernels older than 6.6, the fix will need manual backport.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: btrfs: evitar la desreferencia de puntero NULL si no hay un \u00e1rbol de extensi\u00f3n v\u00e1lido [ERROR] Syzbot inform\u00f3 de un fallo con el siguiente seguimiento de llamada: Informaci\u00f3n de BTRFS (bucle de dispositivo 0): scrub: iniciado en devid 1 ERROR: desreferencia de puntero NULL del kernel, direcci\u00f3n: 0000000000000208 #PF: acceso de lectura de supervisor en modo kernel #PF: error_code(0x0000) - p\u00e1gina no presente PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: cargado Tainted: G O 6.13.0-rc4-custom+ #206 Tainted: [O]=OOT_MODULE Nombre de hardware: PC est\u00e1ndar QEMU (Q35 + ICH9, 2009), BIOS desconocido 02/02/2022 RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs] Seguimiento de llamadas:  Scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs] Scrub_simple_mirror+0x175/0x260 [btrfs] Scrub_stripe+0x5d4/0x6c0 [btrfs] Scrub_chunk+0xbb/0x170 [btrfs] Scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs] btrfs_scrub_dev+0x240/0x600 [btrfs] btrfs_ioctl+0x1dc8/0x2fa0 [btrfs] ? do_sys_openat2+0xa5/0xf0 __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x4f/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e  [CAUSA] El reproductor est\u00e1 usando una imagen da\u00f1ada donde la ra\u00edz del \u00e1rbol de extensi\u00f3n est\u00e1 da\u00f1ada, lo que obliga a usar la opci\u00f3n de montaje \\\"rescue=all,ro\\\" para montar la imagen. Luego, activ\u00f3 una limpieza, pero como la limpieza depende del \u00e1rbol de extensi\u00f3n para encontrar d\u00f3nde est\u00e1n las extensiones de datos/metadatos, scrub_find_fill_first_stripe() depende de una ra\u00edz de extensi\u00f3n no vac\u00eda. Pero desafortunadamente scrub_find_fill_first_stripe() no espera realmente un puntero NULL para la ra\u00edz de la extensi\u00f3n, usa extended_root para obtener fs_info y activa una desreferencia de puntero NULL. [SOLUCI\u00d3N] Agregue una verificaci\u00f3n adicional para una ra\u00edz de extensi\u00f3n v\u00e1lida al comienzo de scrub_find_fill_first_stripe(). La nueva ruta de error es introducida por 42437a6386ff (\\\"btrfs: introduce mount option rescue=ignorebadroots\\\"), pero eso es bastante antiguo, y el commit posterior b979547513ff (\\\"btrfs: scrub: introduce helper to find and fill sector info for a scrub_stripe\\\") cambi\u00f3 la forma en que realizamos el scrub. Entonces, para los kernels anteriores a 6.6, la soluci\u00f3n necesitar\u00e1 una adaptaci\u00f3n manual. \"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-476\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"6.6.72\",\"matchCriteriaId\":\"AD41C3D4-D314-4BC5-888E-E1B87323349D\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.10\",\"matchCriteriaId\":\"02D604F6-10D1-4F7B-A022-0888406A1121\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"62567B3C-6CEE-46D0-BC2E-B3717FBF7D13\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"5A073481-106D-4B15-B4C7-FB0213B8E1D4\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.13:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"DE491969-75AE-4A6B-9A58-8FC5AF98798F\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.13:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"93C0660D-7FB8-4FBA-892A-B064BA71E49E\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"034C36A6-C481-41F3-AE9A-D116E5BE6895\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"8AF9DC49-2085-4FFB-A7E3-73DFAFECC7F2\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/24b85a8b0310e0144da9ab30be42e87e6476638a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/6aecd91a5c5b68939cf4169e32bc49f3cd2dd329\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
  }
}


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