CVE-2026-72380 xen/pvcalls: bound backend response req_id before indexing rsp[]

In the Linux kernel, the following vulnerability has been resolved: xen/pvcalls: bound backend response reqid before indexing rsp pvcallsfronteventhandler takes reqid directly from the backend-supplied ring response and uses it to index the fixed-size bedata-rsp array for a memcpy and a store, wi...