RHSA-2016:1943 - Security Advisory

Topic

An update for kvm is now available for Red Hat Enterprise Linux 5.

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

KVM (for Kernel-based Virtual Machine) is a full virtualization solution for
Linux on x86 hardware. Using KVM, one can run multiple virtual machines running
unmodified Linux or Windows images. Each virtual machine has private virtualized
hardware: a network card, disk, graphics adapter, etc.

Security Fix(es):

• An out-of-bounds read/write access flaw was found in the way QEMU's VGA

emulation with VESA BIOS Extensions (VBE) support performed read/write
operations using I/O port methods. A privileged guest user could use this flaw
to execute arbitrary code on the host with the privileges of the host's QEMU
process. (CVE-2016-3710)

• Quick Emulator(QEMU) built with the virtio framework is vulnerable to an

unbounded memory allocation issue. It was found that a malicious guest user
could submit more requests than the virtqueue size permits. Processing a request
allocates a VirtQueueElement results in unbounded memory allocation on the host
controlled by the guest. (CVE-2016-5403)

Red Hat would like to thank Wei Xiao (360 Marvel Team) and Qinghao Tang (360
Marvel Team) for reporting CVE-2016-3710 and hongzhenhao (Marvel Team) for
reporting CVE-2016-5403.

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

Note: The procedure in the Solution section must be performed before this update
will take effect.

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Workstation 5 x86_64

Fixes

• BZ - 1331401 - CVE-2016-3710 qemu: incorrect banked access bounds checking in vga module
• BZ - 1358359 - CVE-2016-5403 Qemu: virtio: unbounded memory allocation on host via guest leading to DoS

CVEs

• CVE-2016-3710
• CVE-2016-5403

References

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