[PATCH net-next] net: ipv4: Fix NULL pointer dereference in route lookup

[Ido Schimmel]

When calculating the multipath hash for input routes the flow info is
not available and therefore should not be used.

Fixes: 24ba14406c5c ("route: Add multipath_hash in flowi_common to make 
user-define hash")
Signed-off-by: Ido Schimmel <ido...@mellanox.com>
Cc: wenxu <we...@ucloud.cn>
---
 net/ipv4/route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 7cf4c8305071..e3ac458b5d8b 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1820,7 +1820,7 @@ static void ip_multipath_l3_keys(const struct sk_buff 
*skb,
 int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
                       const struct sk_buff *skb, struct flow_keys *flkeys)
 {
-       u32 multipath_hash = fl4->flowi4_multipath_hash;
+       u32 multipath_hash = fl4 ? fl4->flowi4_multipath_hash : 0;
        struct flow_keys hash_keys;
        u32 mhash;
 
-- 
2.20.1