fkie_cve-2025-21658
Vulnerability from fkie_nvd
Published
2025-01-21 13:15
Modified
2025-01-22 23:02
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/24b85a8b0310e0144da9ab30be42e87e6476638aPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6aecd91a5c5b68939cf4169e32bc49f3cd2dd329Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13


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{
  "configurations": [
    {
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  "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. "
    }
  ],
  "id": "CVE-2025-21658",
  "lastModified": "2025-01-22T23:02:59.383",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2025-01-21T13:15:09.437",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "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"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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