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vulnerability CVE-2012-4539

Xen: infinite loop via GNTTABOP_get_status_frames

Synthesis of the vulnerability

A local attacker, who is administrator in a PV guest system, can use the GNTTABOP_get_status_frames hypercall, in order to lock Xen.
Vulnerable systems: XenServer, Debian, Fedora, openSUSE, SUSE Linux Enterprise Desktop, SLES, Unix (platform) ~ not comprehensive.
Severity of this threat: 1/4.
Consequences of an attack: denial of service on server.
Pirate's origin: user shell.
Creation date: 13/11/2012.
Références of this weakness: BID-56498, CERTA-2012-AVI-650, CERTA-2012-AVI-651, CTX135458, CVE-2012-4539, DSA-2582-1, FEDORA-2012-18242, FEDORA-2012-18249, openSUSE-SU-2012:1572-1, openSUSE-SU-2012:1573-1, SUSE-SU-2012:1486-1, SUSE-SU-2012:1487-1, SUSE-SU-2012:1503-1, SUSE-SU-2014:0446-1, VIGILANCE-VUL-12140, XSA-24.

Description of the vulnerability

The Xen hypervisor can be installed on a 64 bit processor, and can provide ParaVirtualized 32 bit systems.

However, in this configuration, the GNTTABOP_get_status_frames hypercall uses twice the same loop control variable. An attacker can then use a malicious hypercall parameter, to generate an infinite loop.

A local attacker, who is administrator in a PV guest system, can therefore use the GNTTABOP_get_status_frames hypercall, in order to lock Xen.
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