x86: Race condition in Xen mapping code

ISSUE DESCRIPTION The Xen code handling the updating of the hypervisor's own pagetables tries to use 2MiB and 1GiB superpages as much as possible to maximize TLB efficiency. Some of the operations for checking and coalescing superpages take non-negligible amount of time; to avoid potential lock...

Design/Logic Flaw

An issue was discovered in Xen through 4.14.x. x86 PV guest kernels can experience denial of service via SYSENTER. The SYSENTER instruction leaves various state sanitization activities to software. One of Xen's sanitization paths injects a GP fault, and incorrectly delivers it twice to the guest...