CVE-2025-37949 (GCVE-0-2025-37949)
Vulnerability from cvelistv5
Published
2025-05-20 16:01
Modified
2025-06-04 12:57
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace: <TASK> __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e is req->cb(req). req->cb is set to xs_wake_up(), a thin wrapper around wake_up(), or xenbus_dev_queue_reply(). It seems like it was xs_wake_up() in this case. It seems like req may have woken up the xs_wait_for_reply(), which kfree()ed the req. When xenbus_thread resumes, it faults on the zero-ed data. Linux Device Drivers 2nd edition states: "Normally, a wake_up call can cause an immediate reschedule to happen, meaning that other processes might run before wake_up returns." ... which would match the behaviour observed. Change to keeping two krefs on each request. One for the caller, and one for xenbus_thread. Each will kref_put() when finished, and the last will free it. This use of kref matches the description in Documentation/core-api/kref.rst
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8e9c8a0393b5f85f1820c565ab8105660f4e8f92
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cbfaf46b88a4c01b64c4186cdccd766c19ae644c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f1bcac367bc95631afbb918348f30dec887d0e1b
Impacted products
Vendor Product Version
Linux Linux Version: fd8aa9095a95c02dcc35540a263267c29b8fda9d
Version: fd8aa9095a95c02dcc35540a263267c29b8fda9d
Version: fd8aa9095a95c02dcc35540a263267c29b8fda9d
Version: fd8aa9095a95c02dcc35540a263267c29b8fda9d
Version: fd8aa9095a95c02dcc35540a263267c29b8fda9d
Version: fd8aa9095a95c02dcc35540a263267c29b8fda9d
Version: fd8aa9095a95c02dcc35540a263267c29b8fda9d
Version: fd8aa9095a95c02dcc35540a263267c29b8fda9d
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{
  "containers": {
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        {
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          "product": "Linux",
          "programFiles": [
            "drivers/xen/xenbus/xenbus.h",
            "drivers/xen/xenbus/xenbus_comms.c",
            "drivers/xen/xenbus/xenbus_dev_frontend.c",
            "drivers/xen/xenbus/xenbus_xs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/xen/xenbus/xenbus.h",
            "drivers/xen/xenbus/xenbus_comms.c",
            "drivers/xen/xenbus/xenbus_dev_frontend.c",
            "drivers/xen/xenbus/xenbus_xs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "4.11"
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              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
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          "nodes": [
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                  "versionEndExcluding": "5.4.294",
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                  "vulnerable": true
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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\nxenbus: Use kref to track req lifetime\n\nMarek reported seeing a NULL pointer fault in the xenbus_thread\ncallstack:\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nRIP: e030:__wake_up_common+0x4c/0x180\nCall Trace:\n \u003cTASK\u003e\n __wake_up_common_lock+0x82/0xd0\n process_msg+0x18e/0x2f0\n xenbus_thread+0x165/0x1c0\n\nprocess_msg+0x18e is req-\u003ecb(req).  req-\u003ecb is set to xs_wake_up(), a\nthin wrapper around wake_up(), or xenbus_dev_queue_reply().  It seems\nlike it was xs_wake_up() in this case.\n\nIt seems like req may have woken up the xs_wait_for_reply(), which\nkfree()ed the req.  When xenbus_thread resumes, it faults on the zero-ed\ndata.\n\nLinux Device Drivers 2nd edition states:\n\"Normally, a wake_up call can cause an immediate reschedule to happen,\nmeaning that other processes might run before wake_up returns.\"\n... which would match the behaviour observed.\n\nChange to keeping two krefs on each request.  One for the caller, and\none for xenbus_thread.  Each will kref_put() when finished, and the last\nwill free it.\n\nThis use of kref matches the description in\nDocumentation/core-api/kref.rst"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-06-04T12:57:34.373Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5"
        },
        {
          "url": "https://git.kernel.org/stable/c/f1bcac367bc95631afbb918348f30dec887d0e1b"
        },
        {
          "url": "https://git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447"
        },
        {
          "url": "https://git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5"
        },
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          "url": "https://git.kernel.org/stable/c/cbfaf46b88a4c01b64c4186cdccd766c19ae644c"
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        },
        {
          "url": "https://git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59"
        },
        {
          "url": "https://git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27"
        }
      ],
      "title": "xenbus: Use kref to track req lifetime",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-37949",
    "datePublished": "2025-05-20T16:01:45.242Z",
    "dateReserved": "2025-04-16T04:51:23.972Z",
    "dateUpdated": "2025-06-04T12:57:34.373Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-37949\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-05-20T16:15:32.920\",\"lastModified\":\"2025-06-04T13:15:27.320\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nxenbus: Use kref to track req lifetime\\n\\nMarek reported seeing a NULL pointer fault in the xenbus_thread\\ncallstack:\\nBUG: kernel NULL pointer dereference, address: 0000000000000000\\nRIP: e030:__wake_up_common+0x4c/0x180\\nCall Trace:\\n \u003cTASK\u003e\\n __wake_up_common_lock+0x82/0xd0\\n process_msg+0x18e/0x2f0\\n xenbus_thread+0x165/0x1c0\\n\\nprocess_msg+0x18e is req-\u003ecb(req).  req-\u003ecb is set to xs_wake_up(), a\\nthin wrapper around wake_up(), or xenbus_dev_queue_reply().  It seems\\nlike it was xs_wake_up() in this case.\\n\\nIt seems like req may have woken up the xs_wait_for_reply(), which\\nkfree()ed the req.  When xenbus_thread resumes, it faults on the zero-ed\\ndata.\\n\\nLinux Device Drivers 2nd edition states:\\n\\\"Normally, a wake_up call can cause an immediate reschedule to happen,\\nmeaning that other processes might run before wake_up returns.\\\"\\n... which would match the behaviour observed.\\n\\nChange to keeping two krefs on each request.  One for the caller, and\\none for xenbus_thread.  Each will kref_put() when finished, and the last\\nwill free it.\\n\\nThis use of kref matches the description in\\nDocumentation/core-api/kref.rst\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: xenbus: Usar kref para rastrear el tiempo de vida de req. Marek inform\u00f3 haber visto un fallo de puntero nulo en la pila de llamadas xenbus_thread: ERROR: desreferencia de puntero nulo del kernel, direcci\u00f3n: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Rastreo de llamadas:  __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e es req-\u0026gt;cb(req). req-\u0026gt;cb est\u00e1 configurado como xs_wake_up(), una envoltura ligera alrededor de wake_up(), o xenbus_dev_queue_reply(). Parece que en este caso era xs_wake_up(). Parece que req pudo haber despertado xs_wait_for_reply(), que liber\u00f3 la solicitud. Cuando xenbus_thread se reanuda, falla en los datos con ceros. La segunda edici\u00f3n de los controladores de dispositivos de Linux indica: \u00abNormalmente, una llamada wake_up puede provocar una reprogramaci\u00f3n inmediata, lo que significa que otros procesos podr\u00edan ejecutarse antes de que wake_up regrese\u00bb. ... lo cual coincidir\u00eda con el comportamiento observado. Se recomienda mantener dos krefs en cada solicitud: uno para el que realiza la llamada y otro para xenbus_thread. Cada uno ejecutar\u00e1 kref_put() al finalizar, y el \u00faltimo lo liberar\u00e1. Este uso de kref coincide con la descripci\u00f3n en Documentation/core-api/kref.rst.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0e94a246bb6d9538010b6c02d2b1d4717a97b2e5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2466b0f66795c3c426cacc8998499f38031dbb59\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/4d260a5558df4650eb87bc41b2c9ac2d6b2ba447\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8b02f85e84dc6f7c150cef40ddb69af5a25659e5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8e9c8a0393b5f85f1820c565ab8105660f4e8f92\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cbfaf46b88a4c01b64c4186cdccd766c19ae644c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f1bcac367bc95631afbb918348f30dec887d0e1b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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