RHSA-2017:1206 - Security Advisory

Topic

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.

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.

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.

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64

Fixes

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

CVEs

• CVE-2016-9603
• CVE-2017-2633
• CVE-2017-7718
• CVE-2017-7980

References

• https://access.redhat.com/security/updates/classification/#important