kernel: stack corruption in xen_failsafe_callback()

The xenfailsafecallback function in Xen for the Linux kernel 2.6.23 and other versions, when running a 32-bit PVOPS guest, allows local users to cause a denial of service guest crash by triggering an iret fault, leading to use of an incorrect stack pointer and stack corruption...

Linux stack corruption in xen_failsafe_callback for 32bit PVOPS guests.

ISSUE DESCRIPTION xenfailsafecallback incorrectly sets up its stack if an iret fault is injected by the hypervisor. IMPACT Malicious or buggy unprivileged userspace can cause the guest kernel to crash, or operate erroneously. VULNERABLE SYSTEMS All 32bit PVOPS versions of Linux are affected, sinc...