CVE-2014-3610

Published: 23 October 2014

The WRMSR processing functionality in the KVM subsystem in the Linux kernel through 3.17.2 does not properly handle the writing of a non-canonical address to a model-specific register, which allows guest OS users to cause a denial of service (host OS crash) by leveraging guest OS privileges, related to the wrmsr_interception function in arch/x86/kvm/svm.c and the handle_wrmsr function in arch/x86/kvm/vmx.c. A privileged guest user can use this flaw to crash the host. Enabling CONFIG_PARAVIRT when building the kernel mitigates this issue because wrmsrl() ends up invoking safe msr write variant.

From the Ubuntu Security Team

Lars Bull and Nadav Amit reported a flaw in how KVM (the Kernel Virtual Machine) handles noncanonical writes to certain MSR registers. A privileged guest user can exploit this flaw to cause a denial of service (kernel panic) on the host.

Notes

android kernels (flo, goldfish, grouper, maguro, mako and manta) are
not supported on the Ubuntu Touch 14.04 preview kernels
linux-lts-saucy no longer receives official support
linux-lts-quantal no longer receives official support
CVE disclosure was part of miscoordinated CRD (various (incomplete)
commits were publicly leaked by other vendors and upstream before the embargo
was lifted).
Updates for linux on Ubuntu 14.04 LTS were made available to users
on 2014/10/28 but due to a process error, USN publication did not happen
until 2014/10/30.
Updates for linux-lts-trusty on Ubuntu 12.04 LTS were made available
to users on 2014/10/29 but due to a process error, USN publication did not
happen until 2014/10/30.
Updates for linux on Ubuntu 14.10 were made available to users on
2014/10/28 but due to a process error, USN publication did not happen until
2014/10/31.

According to http://seclists.org/oss-sec/2014/q4/438 a second commit is
required; however, commit 8b3c3104c3f4f706e99365c3e0d2aa61b95f969f is
just a 'nice to have', but not really fixing this CVE.

Status

Severity score breakdown

References

• https://ubuntu.com/security/notices/USN-2394-1
• https://ubuntu.com/security/notices/USN-2395-1
• https://ubuntu.com/security/notices/USN-2396-1
• https://ubuntu.com/security/notices/USN-2417-1
• https://ubuntu.com/security/notices/USN-2418-1
• https://ubuntu.com/security/notices/USN-2462-1
• https://ubuntu.com/security/notices/USN-2491-1
• https://www.cve.org/CVERecord?id=CVE-2014-3610
• NVD
• Launchpad
• Debian

Bugs

• https://launchpad.net/bugs/1384539