xfrm: Fix return value check of copy_sec_ctx.

A recent commit added an output_mark. When copying
this output_mark, the return value of copy_sec_ctx
is overwitten without a check. Fix this by copying
the output_mark before the security context.

Fixes: 077fbac4 ("net: xfrm: support setting an output mark.")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_user.c

@@ -900,13 +900,13 @@ static int copy_to_user_state_extra(struct xfrm_state *x,
 		ret = copy_user_offload(&x->xso, skb);
 	if (ret)
 		goto out;
-	if (x->security)
-		ret = copy_sec_ctx(x->security, skb);
 	if (x->props.output_mark) {
 		ret = nla_put_u32(skb, XFRMA_OUTPUT_MARK, x->props.output_mark);
 		if (ret)
 			goto out;
 	}
+	if (x->security)
+		ret = copy_sec_ctx(x->security, skb);
 out:
 	return ret;
 }