inet: Fix BUG triggered by __rt{,6}_get_peer().

If no peer actually gets attached (either because create is zero or
the peer allocation fails) we'll trigger a BUG because we
unconditionally do an rt{,6}_peer_ptr() afterwards.

Fix this by guarding it with the proper check.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/ip6_route.h

@@ -61,7 +61,7 @@ static inline struct inet_peer *__rt6_get_peer(struct rt6_info *rt, int create)
 		return rt6_peer_ptr(rt);
 
 	rt6_bind_peer(rt, create);
-	return rt6_peer_ptr(rt);
+	return (rt6_has_peer(rt) ? rt6_peer_ptr(rt) : NULL);
 }
 
 static inline struct inet_peer *rt6_get_peer(struct rt6_info *rt)

include/net/route.h

@@ -334,7 +334,7 @@ static inline struct inet_peer *__rt_get_peer(struct rtable *rt, __be32 daddr, i
 		return rt_peer_ptr(rt);
 
 	rt_bind_peer(rt, daddr, create);
-	return rt_peer_ptr(rt);
+	return (rt_has_peer(rt) ? rt_peer_ptr(rt) : NULL);
 }
 
 static inline struct inet_peer *rt_get_peer(struct rtable *rt, __be32 daddr)