xen: vm_event: do not do vm_event_op for an invalid domain

A privileged domain can issue XEN_DOMCTL_vm_event_op with
op->domain == DOMID_INVALID. In this case vm_event_domctl()
function will get NULL as the first parameter and this will
cause hypervisor panic, as it tries to derefer this pointer.

Fix the issue by checking if valid domain is passed in.

Fixes: 48b84249459f ("xen/vm-event: Drop unused u_domctl parameter from vm_event_domctl()")
Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>

diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index fbf1aa08481fe0853f840c59c9482f50db1af675..1666ff615f35bca17bd5560c636ca45997e38c5a 100644 (file)
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -600,6 +600,10 @@ int vm_event_domctl(struct domain *d, struct xen_domctl_vm_event_op *vec)
         return 0;
     }
 
+    /* All other subops need to target a real domain. */
+    if ( unlikely(d == NULL) )
+        return -ESRCH;
+
     rc = xsm_vm_event_control(XSM_PRIV, d, vec->mode, vec->op);
     if ( rc )
         return rc;