xfrm Fix potential error pointer dereference in xfrm_bundle_create.

We may derference an invalid pointer in the error path of
xfrm_bundle_create(). Fix this by returning this error
pointer directly instead of assigning it to xdst0.

Fixes: 45b018beddb6 ("ipsec: Create and use new helpers for dst child access.")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_policy.c

@@ -1658,7 +1658,6 @@ static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
 		trailer_len -= xdst_prev->u.dst.xfrm->props.trailer_len;
 	}
 
-out:
 	return &xdst0->u.dst;
 
 put_states:
@@ -1667,8 +1666,8 @@ put_states:
 free_dst:
 	if (xdst0)
 		dst_release_immediate(&xdst0->u.dst);
-	xdst0 = ERR_PTR(err);
-	goto out;
+
+	return ERR_PTR(err);
 }
 
 static int xfrm_expand_policies(const struct flowi *fl, u16 family,