diff --git a/include/net/netlink.h b/include/net/netlink.h
index 64158353ecb2750a3165dc07e915755ccb801522..d5869b90bfbb96108d35cee19eb9642b70bb4c63 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -520,8 +520,10 @@ static inline void *nlmsg_get_pos(struct sk_buff *skb)
  */
 static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
 {
-	if (mark)
+	if (mark) {
+		WARN_ON((unsigned char *) mark < skb->data);
 		skb_trim(skb, (unsigned char *) mark - skb->data);
+	}
 }
 
 /**