Red Hat Bugzilla – Full Text Bug Listing
|Summary:||CVE-2013-1917 kernel: xen: Xen PV DoS vulnerability with SYSENTER|
|Product:||[Other] Security Response||Reporter:||Petr Matousek <pmatouse>|
|Component:||vulnerability||Assignee:||Red Hat Product Security <security-response-team>|
|Status:||CLOSED NOTABUG||QA Contact:|
|Version:||unspecified||CC:||dlaor, drjones, imammedo, lersek, pbonzini, security-response-team|
|Fixed In Version:||Doc Type:||Bug Fix|
|Doc Text:||Story Points:||---|
|Last Closed:||2013-05-13 04:01:43 EDT||Type:||---|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Bug Depends On:||953569|
Description Petr Matousek 2013-04-10 11:34:23 EDT
The SYSENTER instruction can be used by PV guests to accelerate system call processing. This instruction, however, leaves the EFLAGS register mostly unmodified - in particular, the NT flag doesn't get cleared. If the hypervisor subsequently uses IRET to return to the guest (which it will always do if the guest is a 32-bit one), that instruction will cause a #GP fault to be raised, but the recovery code in the hypervisor will again try to use IRET without intermediately clearing the NT flag. The #GP fault raised on this second IRET is a fatal event, causing the hypervisor to crash. Malicious or buggy unprivileged user space can cause the entire host to crash. The vulnerability is only exposed by 64-bit PV guests running on Intel CPUs. Acknowledgements: Red Hat would like to thank the Xen for reporting this issue.
Comment 1 Petr Matousek 2013-04-10 11:37:22 EDT
Statement: Not vulnerable. This issue did not affect the versions of the kernel-xen package as shipped with Red Hat Enterprise Linux 5 as we did not have support for sysenter for 64bit PV guests running on the Xen hypervisor (introduced in upstream changeset 16207:aeebd173c3fa). This issue did not affect the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 6 and Red Hat Enterprise MRG as we did not have support for Xen hypervisor.
Comment 3 Petr Matousek 2013-04-18 09:44:44 EDT
Created xen tracking bugs for this issue Affects: fedora-all [bug 953569]
Comment 4 Fedora Update System 2013-05-04 22:25:11 EDT
xen-4.1.5-1.fc17 has been pushed to the Fedora 17 stable repository. If problems still persist, please make note of it in this bug report.
Comment 5 Fedora Update System 2013-05-04 22:25:48 EDT
xen-4.2.2-1.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.