fkie_cve-2022-49771
Vulnerability from fkie_nvd
Published
2025-05-01 15:16
Modified
2025-05-02 13:53
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
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0c8d4112df329bf3dfbf27693f918c3b08676538
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3a1c35d72dc0b34d1e746ed705790c0f630aa427
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4fe1ec995483737f3d2a14c3fe1d8fe634972979
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5398b8e275bf81a2517b327d216c0f37ac9ac5ae
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6a818db0d5aecf80d4ba9e10ac153f60adc629ca
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6ffce7a92ef5c68f7e5d6f4d722c2f96280c064b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b545c0e1e4094d4de2bdfe9a3823f9154b0c0005
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f59f5a269ca5e43c567aca7f1f52500a0186e9b7
Impacted products
Vendor Product Version


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{
  "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)\"."
    }
  ],
  "id": "CVE-2022-49771",
  "lastModified": "2025-05-02T13:53:20.943",
  "metrics": {},
  "published": "2025-05-01T15:16:00.237",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "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"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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