vulnerability bulletin CVE-2012-4461
Linux kernel: denial of service via XSAVE
Synthesis of the vulnerability
An attacker, who is located in a qemu+KVM guest system, and on a host system using a processor without xsave/xrstor, can stop the host system.Impacted products: Debian
, BIG-IP Appliance
, SUSE Linux Enterprise Desktop
BID-56414, CERTA-2012-AVI-633, CVE-2012-4461, DSA-2668-1, FEDORA-2012-18684, FEDORA-2012-18691, openSUSE-SU-2013:0925-1, openSUSE-SU-2013:0927-1, RHSA-2013:0223-01, RHSA-2013:0882-01, SOL15797, SUSE-SU-2012:1679-1, SUSE-SU-2013:0786-1, VIGILANCE-VUL-12118.
Description of the vulnerability
The x86 "xsave" and "xrstor" assembler instructions manage the extended state of the processor. These instructions are supported by processors created since 2008.
A user (in a guest system) can use the KVM_SET_SREGS ioctl to set the bit X86_CR4_OSXSAVE in the CR4 register, and can then use the KVM_RUN ioctl. In this case, the kvm_arch_vcpu_ioctl_set_sregs() function uses xsave/xrstor. However, if the processor is anterior to 2008, it does not recognize these instructions, which stops the kernel on the host system.
An attacker, who is located in a qemu+KVM guest system, and on a host system using a processor without xsave/xrstor, can therefore stop the host system.Complete Vigil@nce bulletin....
Share this bulletin
Computer vulnerabilities tracking service
Vigil@nce provides software vulnerabilities analysis
. The Vigil@nce vulnerability database contains several thousand vulnerabilities. Each administrator can customize the list of products for which he wants to receive vulnerability alerts. The technology watch team tracks security threats targeting the computer system.