|Bugzilla:||813428: CVE-2012-0217 kernel: x86-64: avoid sysret to non-canonical address|
It was found that the Xen hypervisor implementation as shipped with Red Hat Enterprise Linux 5 did not properly restrict the syscall return addresses in the sysret return path to canonical addresses. An unprivileged user in a 64-bit para-virtualized guest, that is running on a 64-bit host that has an Intel CPU, could use this flaw to crash the host or, potentially, escalate their privileges, allowing them to execute arbitrary code at the hypervisor level.
This issue did not affect the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 5 and 6, and Red Hat Enterprise MRG, as those versions have a guard page between the end of the user-mode accessible virtual address space and the beginning of the non-canonical area due to CVE-2005-1764 fix, and hardened system call handler due to CVE-2006-0744 fix.
This issue did affect the versions of Xen hypervisor as shipped with Red Hat Enterprise Linux 5. A kernel-xen update for Red Hat Enterprise Linux 5 is available to address this flaw.
CVSS v2 metrics
|Access Vector:||Adjacent Network|
Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).
Red Hat security errata
|Red Hat Enterprise Linux EUS (v. 5.6 server) (kernel)||RHSA-2012:0720||June 12, 2012|
|Red Hat Enterprise Linux version 5 (kernel)||RHSA-2012:0721||June 12, 2012|
Red Hat would like to thank the Xen project for reporting this issue. Upstream acknowledges Rafal Wojtczuk as the original reporter.
This page is generated automatically and has not been checked for errors or omissions.
For clarification or corrections please contact the Red Hat Security Response Team.