(RHSA-2017:0396) Important: qemu-kvm security and bug fix update

Kernel-based Virtual Machine (KVM) is a full virtualization solution for Linux on a variety of architectures. The qemu-kvm packages provide the user-space component for running virtual machines that use KVM.

Security Fix(es):

• Quick emulator (QEMU) built with the Cirrus CLGD 54xx VGA emulator support is vulnerable to an out-of-bounds access issue. It could occur while copying VGA data via bitblt copy in backward mode. A privileged user inside a guest could use this flaw to crash the QEMU process resulting in DoS or potentially execute arbitrary code on the host with privileges of QEMU process on the host. (CVE-2017-2615)

• Quick emulator (QEMU) built with the Cirrus CLGD 54xx VGA Emulator support is vulnerable to an out-of-bounds access issue. The issue could occur while copying VGA data in cirrus_bitblt_cputovideo. A privileged user inside guest could use this flaw to crash the QEMU process OR potentially execute arbitrary code on host with privileges of the QEMU process. (CVE-2017-2620)

Red Hat would like to thank Wjjzhang (Tencent.com Inc.) and Li Qiang (360.cn Inc.) for reporting CVE-2017-2615.

Bug Fix(es):

• When using the virtio-blk driver on a guest virtual machine with no space on the virtual hard drive, the guest terminated unexpectedly with a “block I/O error in device” message and the qemu-kvm process exited with a segmentation fault. This update fixes how the system_reset QEMU signal is handled in the above scenario. As a result, if a guest crashes due to no space left on the device, qemu-kvm continues running and the guest can be reset as expected. (BZ#1420049)