xfrm: fix XFRMA_MARK extraction in xfrm_mark_get

Determine the size of the xfrm_mark struct, not of its pointer.
Signed-off-by: Andreas Steffen <andreas.steffen@strongswan.org>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/xfrm.h

@@ -1586,7 +1586,7 @@ static inline struct xfrm_state *xfrm_input_state(struct sk_buff *skb)
 static inline int xfrm_mark_get(struct nlattr **attrs, struct xfrm_mark *m)
 {
 	if (attrs[XFRMA_MARK])
-		memcpy(m, nla_data(attrs[XFRMA_MARK]), sizeof(m));
+		memcpy(m, nla_data(attrs[XFRMA_MARK]), sizeof(struct xfrm_mark));
 	else
 		m->v = m->m = 0;