9 - RHSA-2017:1206

Problem Description:

An update for qemu-kvm is now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Desktop (v. 6) - i386, x86_64 Red Hat Enterprise Linux HPC Node (v. 6) - x86_64 Red Hat Enterprise Linux Server (v. 6) - i386, ppc64, x86_64 Red Hat Enterprise Linux Workstation (v. 6) - i386, x86_64

3. Description:

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

Security Fix(es):

* A heap buffer overflow flaw was found in QEMU's Cirrus CLGD 54xx VGA emulator's VNC display driver support; the issue could occur when a VNC client attempted to update its display after a VGA operation is performed by a guest. A privileged user/process inside a guest could use this flaw to crash the QEMU process or, potentially, execute arbitrary code on the host with privileges of the QEMU process. (CVE-2016-9603)

* An out-of-bounds r/w access issue was found in QEMU's Cirrus CLGD 54xx VGA Emulator support. The vulnerability could occur while copying VGA data via various bitblt functions. A privileged user inside a guest could use this flaw to crash the QEMU process or, potentially, execute arbitrary code on the host with privileges of the QEMU process. (CVE-2017-7980)

* An out-of-bounds memory access issue was found in QEMU's VNC display driver support. The vulnerability could occur while refreshing the VNC display surface area in the 'vnc_refresh_server_surface'. A user/process inside a guest could use this flaw to crash the QEMU process, resulting in a denial of service. (CVE-2017-2633)

* An out-of-bounds access issue was found in QEMU's Cirrus CLGD 54xx VGA Emulator support. The vulnerability could occur while copying VGA data using bitblt functions (for example, cirrus_bitblt_rop_fwd_transp_). A privileged user inside a guest could use this flaw to crash the QEMU process, resulting in denial of service. (CVE-2017-7718)

Red Hat would like to thank Jiangxin (PSIRT Huawei Inc.) and Li Qiang (Qihoo 360 Gear Team) for reporting CVE-2017-7980 and Jiangxin (PSIRT Huawei Inc.) for reporting CVE-2017-7718.

4. Solution:

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, shut down all running virtual machines. Once all virtual machines have shut down, start them again for this update to take effect.

5. Bugs fixed (https://bugzilla.redhat.com/):

1400438 - CVE-2017-2633 qemu-kvm coredump in vnc_refresh_server_surface [rhel-6.9.z] 1425939 - CVE-2017-2633 Qemu: VNC: memory corruption due to unchecked resolution limit 1430056 - CVE-2016-9603 Qemu: cirrus: heap buffer overflow via vnc connection 1437060 - Fails to build in brew 1443441 - CVE-2017-7718 Qemu: display: cirrus: OOB read access issue 1444371 - CVE-2017-7980 Qemu: display: cirrus: OOB r/w access issues in bitblt routines