check for out-of-bounds index when freeing a VM

diff --git a/linux_module/main.c b/linux_module/main.c
index fdab7b3..17229c5 100644 (file)
--- a/linux_module/main.c
+++ b/linux_module/main.c
@@ -141,7 +141,14 @@ out_err:
        }
        case V3_FREE_GUEST: {
            unsigned long vm_idx = arg;
-           struct v3_guest * guest = guest_map[vm_idx];
+            struct v3_guest * guest;
+
+            if (vm_idx > MAX_VMS) {
+                ERROR("Invalid VM index: %ld\n", vm_idx);
+                return -1;
+            }
+
+           guest = guest_map[vm_idx];
 
            if (!guest) {
                ERROR("No VM at index %ld\n",vm_idx);