CVE-2017-11334

La función address_space_write_continue en exec.c en QEMU (también conocido como Quick Emulator) permite a los usuarios invitado locales con privilegios del sistema operativo provocar una denegación de servicio (acceso fuera de los límites y detención de las instancias de la cuenta de invitado) usando qemu_map_ram_ptr para acceder al área del bloque de memoria ram del invitado.

Quick Emulator (QEMU), compiled with qemu_map_ram_ptr to access guests' RAM block area, is vulnerable to an OOB r/w access issue. The crash can occur if a privileged user inside a guest conducts certain DMA operations, resulting in a DoS.

USN-3575-1 fixed vulnerabilities in QEMU. The fix for CVE-2017-11334 caused a regression in Xen environments. This update removes the problematic fix pending further investigation. It was discovered that QEMU incorrectly handled guest ram. A privileged attacker inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. David Buchanan discovered that QEMU incorrectly handled the VGA device. A privileged attacker inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service. This issue was only addressed in Ubuntu 17.10. Thomas Garnier discovered that QEMU incorrectly handled multiboot. An attacker could use this issue to cause QEMU to crash, resulting in a denial of service, or possibly execute arbitrary code on the host. In the default installation, when QEMU is used with libvirt, attackers would be isolated by the libvirt AppArmor profile. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. Various other issues were also addressed.