af-packet: check out_iface not NULL

src/runmode-af-packet.c

@@ -287,8 +287,12 @@ static void *ParseAFPConfig(const char *iface)
     }
 
     if (ConfGetChildValueWithDefault(if_root, if_default, "copy-iface", &out_iface) == 1) {
-        if (strlen(out_iface) > 0) {
+        if (out_iface != NULL) {
-            aconf->out_iface = out_iface;
+            if (strlen(out_iface) > 0) {
+                aconf->out_iface = out_iface;
+            }
+        } else {
+            SCLogWarning("copy-iface corresponding to %s interface cannot be NULL", iface);
         }
     }