CVE-2022-49771 (GCVE-0-2022-49771)
Vulnerability from cvelistv5
Published
2025-05-01 14:09
Modified
2025-05-04 08:45
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: dm ioctl: fix misbehavior if list_versions races with module loading __list_versions will first estimate the required space using the "dm_target_iterate(list_version_get_needed, &needed)" call and then will fill the space using the "dm_target_iterate(list_version_get_info, &iter_info)" call. Each of these calls locks the targets using the "down_read(&_lock)" and "up_read(&_lock)" calls, however between the first and second "dm_target_iterate" there is no lock held and the target modules can be loaded at this point, so the second "dm_target_iterate" call may need more space than what was the first "dm_target_iterate" returned. The code tries to handle this overflow (see the beginning of list_version_get_info), however this handling is incorrect. The code sets "param->data_size = param->data_start + needed" and "iter_info.end = (char *)vers+len" - "needed" is the size returned by the first dm_target_iterate call; "len" is the size of the buffer allocated by userspace. "len" may be greater than "needed"; in this case, the code will write up to "len" bytes into the buffer, however param->data_size is set to "needed", so it may write data past the param->data_size value. The ioctl interface copies only up to param->data_size into userspace, thus part of the result will be truncated. Fix this bug by setting "iter_info.end = (char *)vers + needed;" - this guarantees that the second "dm_target_iterate" call will write only up to the "needed" buffer and it will exit with "DM_BUFFER_FULL_FLAG" if it overflows the "needed" space - in this case, userspace will allocate a larger buffer and retry. Note that there is also a bug in list_version_get_needed - we need to add "strlen(tt->name) + 1" to the needed size, not "strlen(tt->name)".
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/dm-ioctl.c"
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          "vendor": "Linux",
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              "version": "5.4.225",
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              "status": "unaffected",
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              "status": "unaffected",
              "version": "6.0.10",
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.1",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm ioctl: fix misbehavior if list_versions races with module loading\n\n__list_versions will first estimate the required space using the\n\"dm_target_iterate(list_version_get_needed, \u0026needed)\" call and then will\nfill the space using the \"dm_target_iterate(list_version_get_info,\n\u0026iter_info)\" call. Each of these calls locks the targets using the\n\"down_read(\u0026_lock)\" and \"up_read(\u0026_lock)\" calls, however between the first\nand second \"dm_target_iterate\" there is no lock held and the target\nmodules can be loaded at this point, so the second \"dm_target_iterate\"\ncall may need more space than what was the first \"dm_target_iterate\"\nreturned.\n\nThe code tries to handle this overflow (see the beginning of\nlist_version_get_info), however this handling is incorrect.\n\nThe code sets \"param-\u003edata_size = param-\u003edata_start + needed\" and\n\"iter_info.end = (char *)vers+len\" - \"needed\" is the size returned by the\nfirst dm_target_iterate call; \"len\" is the size of the buffer allocated by\nuserspace.\n\n\"len\" may be greater than \"needed\"; in this case, the code will write up\nto \"len\" bytes into the buffer, however param-\u003edata_size is set to\n\"needed\", so it may write data past the param-\u003edata_size value. The ioctl\ninterface copies only up to param-\u003edata_size into userspace, thus part of\nthe result will be truncated.\n\nFix this bug by setting \"iter_info.end = (char *)vers + needed;\" - this\nguarantees that the second \"dm_target_iterate\" call will write only up to\nthe \"needed\" buffer and it will exit with \"DM_BUFFER_FULL_FLAG\" if it\noverflows the \"needed\" space - in this case, userspace will allocate a\nlarger buffer and retry.\n\nNote that there is also a bug in list_version_get_needed - we need to add\n\"strlen(tt-\u003ename) + 1\" to the needed size, not \"strlen(tt-\u003ename)\"."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-04T08:45:01.509Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0c8d4112df329bf3dfbf27693f918c3b08676538"
        },
        {
          "url": "https://git.kernel.org/stable/c/6a818db0d5aecf80d4ba9e10ac153f60adc629ca"
        },
        {
          "url": "https://git.kernel.org/stable/c/3a1c35d72dc0b34d1e746ed705790c0f630aa427"
        },
        {
          "url": "https://git.kernel.org/stable/c/b545c0e1e4094d4de2bdfe9a3823f9154b0c0005"
        },
        {
          "url": "https://git.kernel.org/stable/c/f59f5a269ca5e43c567aca7f1f52500a0186e9b7"
        },
        {
          "url": "https://git.kernel.org/stable/c/6ffce7a92ef5c68f7e5d6f4d722c2f96280c064b"
        },
        {
          "url": "https://git.kernel.org/stable/c/5398b8e275bf81a2517b327d216c0f37ac9ac5ae"
        },
        {
          "url": "https://git.kernel.org/stable/c/4fe1ec995483737f3d2a14c3fe1d8fe634972979"
        }
      ],
      "title": "dm ioctl: fix misbehavior if list_versions races with module loading",
      "x_generator": {
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    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2022-49771",
    "datePublished": "2025-05-01T14:09:08.813Z",
    "dateReserved": "2025-04-16T07:17:33.805Z",
    "dateUpdated": "2025-05-04T08:45:01.509Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2022-49771\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-05-01T15:16:00.237\",\"lastModified\":\"2025-05-02T13:53:20.943\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\ndm ioctl: fix misbehavior if list_versions races with module loading\\n\\n__list_versions will first estimate the required space using the\\n\\\"dm_target_iterate(list_version_get_needed, \u0026needed)\\\" call and then will\\nfill the space using the \\\"dm_target_iterate(list_version_get_info,\\n\u0026iter_info)\\\" call. Each of these calls locks the targets using the\\n\\\"down_read(\u0026_lock)\\\" and \\\"up_read(\u0026_lock)\\\" calls, however between the first\\nand second \\\"dm_target_iterate\\\" there is no lock held and the target\\nmodules can be loaded at this point, so the second \\\"dm_target_iterate\\\"\\ncall may need more space than what was the first \\\"dm_target_iterate\\\"\\nreturned.\\n\\nThe code tries to handle this overflow (see the beginning of\\nlist_version_get_info), however this handling is incorrect.\\n\\nThe code sets \\\"param-\u003edata_size = param-\u003edata_start + needed\\\" and\\n\\\"iter_info.end = (char *)vers+len\\\" - \\\"needed\\\" is the size returned by the\\nfirst dm_target_iterate call; \\\"len\\\" is the size of the buffer allocated by\\nuserspace.\\n\\n\\\"len\\\" may be greater than \\\"needed\\\"; in this case, the code will write up\\nto \\\"len\\\" bytes into the buffer, however param-\u003edata_size is set to\\n\\\"needed\\\", so it may write data past the param-\u003edata_size value. The ioctl\\ninterface copies only up to param-\u003edata_size into userspace, thus part of\\nthe result will be truncated.\\n\\nFix this bug by setting \\\"iter_info.end = (char *)vers + needed;\\\" - this\\nguarantees that the second \\\"dm_target_iterate\\\" call will write only up to\\nthe \\\"needed\\\" buffer and it will exit with \\\"DM_BUFFER_FULL_FLAG\\\" if it\\noverflows the \\\"needed\\\" space - in this case, userspace will allocate a\\nlarger buffer and retry.\\n\\nNote that there is also a bug in list_version_get_needed - we need to add\\n\\\"strlen(tt-\u003ename) + 1\\\" to the needed size, not \\\"strlen(tt-\u003ename)\\\".\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: dm ioctl: se corrige el comportamiento incorrecto si list_versions se acelera al cargar m\u00f3dulos. __list_versions primero estimar\u00e1 el espacio requerido mediante la llamada \\\"dm_target_iterate(list_version_get_needed, \u0026amp;needed)\\\" y luego llenar\u00e1 el espacio mediante la llamada \\\"dm_target_iterate(list_version_get_info, \u0026amp;iter_info)\\\". Cada una de estas llamadas bloquea los destinos mediante las llamadas \\\"down_read(\u0026amp;_lock)\\\" y \\\"up_read(\u0026amp;_lock)\\\". Sin embargo, entre la primera y la segunda llamada \\\"dm_target_iterate\\\" no se mantiene el bloqueo y los m\u00f3dulos de destino se pueden cargar en este punto, por lo que la segunda llamada \\\"dm_target_iterate\\\" podr\u00eda necesitar m\u00e1s espacio que el devuelto por la primera llamada \\\"dm_target_iterate\\\". El c\u00f3digo intenta gestionar este desbordamiento (v\u00e9ase el comienzo de list_version_get_info), pero esta gesti\u00f3n es incorrecta. El c\u00f3digo establece \\\"param-\u0026gt;data_size = param-\u0026gt;data_start + needed\\\" y \\\"iter_info.end = (char *)vers+len\\\": \\\"needed\\\" es el tama\u00f1o devuelto por la primera llamada a dm_target_iterate; \\\"len\\\" es el tama\u00f1o del b\u00fafer asignado por el espacio de usuario. \\\"len\\\" puede ser mayor que \\\"needed\\\"; en este caso, el c\u00f3digo escribir\u00e1 hasta \\\"len\\\" bytes en el b\u00fafer; sin embargo, param-\u0026gt;data_size se establece en \\\"needed\\\", por lo que podr\u00eda escribir datos que superen el valor de param-\u0026gt;data_size. La interfaz ioctl solo copia hasta param-\u0026gt;data_size en el espacio de usuario, por lo que parte del resultado se truncar\u00e1. Corrija este error estableciendo \\\"iter_info.end = (char *)vers + needed;\\\" Esto garantiza que la segunda llamada \\\"dm_target_iterate\\\" solo escriba hasta el b\u00fafer necesario y finalice con \\\"DM_BUFFER_FULL_FLAG\\\" si se desborda dicho espacio. En este caso, el espacio de usuario asignar\u00e1 un b\u00fafer mayor y reintentar\u00e1. Tenga en cuenta que tambi\u00e9n hay un error en list_version_get_needed: debemos agregar \\\"strlen(tt-\u0026gt;name) + 1\\\" al tama\u00f1o necesario, no \\\"strlen(tt-\u0026gt;name)\\\".\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0c8d4112df329bf3dfbf27693f918c3b08676538\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3a1c35d72dc0b34d1e746ed705790c0f630aa427\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/4fe1ec995483737f3d2a14c3fe1d8fe634972979\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5398b8e275bf81a2517b327d216c0f37ac9ac5ae\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6a818db0d5aecf80d4ba9e10ac153f60adc629ca\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6ffce7a92ef5c68f7e5d6f4d722c2f96280c064b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b545c0e1e4094d4de2bdfe9a3823f9154b0c0005\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f59f5a269ca5e43c567aca7f1f52500a0186e9b7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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