CVE-2018-16872

A flaw was found in qemu Media Transfer Protocol (MTP). The code opening files in usb_mtp_get_object and usb_mtp_get_partial_object and directories in usb_mtp_object_readdir doesn't consider that the underlying filesystem may have changed since the time lstat(2) was called in usb_mtp_object_alloc, a classical TOCTTOU problem. An attacker with write access to the host filesystem shared with a guest can use this property to navigate the host filesystem in the context of the QEMU process and read any file the QEMU process has access to. Access to the filesystem may be local or via a network share protocol such as CIFS.

A flaw was found in qemu Media Transfer Protocol (MTP). The code opening files in usb_mtp_get_object and usb_mtp_get_partial_object and directories in usb_mtp_object_readdir doesn't consider that the underlying filesystem may have changed since the time lstat(2) was called in usb_mtp_object_alloc, a classical TOCTTOU problem. An attacker with write access to the host filesystem shared with a guest can use this property to navigate the host filesystem in the context of the QEMU process and read any file the QEMU process has access to. Access to the filesystem may be local or via a network share protocol such as CIFS.

Se ha detectado un error en el protocolo MTP (Media Transfer Protocol) de QEMU. El código que abre archivos en usb_mtp_get_object y usb_mtp_get_partial_object, y directorios en usb_mtp_object_readdir, no considera que el sistema de archivos subyacente ha podido cambiar desde que lstat(2) se llamó en usb_mtp_object_alloc. Este es un típico problema TOCTTOU. Un atacante con acceso de escritura al sistema de archivos del host compartido con un invitado puede emplear esta propiedad para navegar por el sistema de archivos del host en el contexto del proceso QEMU y leer cualquier archivo al que tenga acceso el proceso QEMU. El acceso al sistema de archivos puede ser local o mediante un protocolo de compartición de red como CIFS.