inet: ip_skb_dst_mtu() should use sk_fullsock()

SYN_RECV & TIMEWAIT sockets are not full blown,
do not even try to call ip_sk_use_pmtu() on them.

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip.h b/include/net/ip.h
index 91a6b2c..aa78119 100644 (file)
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -323,12 +323,15 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
 
 static inline unsigned int ip_skb_dst_mtu(const struct sk_buff *skb)
 {
-       if (!skb->sk || ip_sk_use_pmtu(skb->sk)) {
+       struct sock *sk = skb->sk;
+
+       if (!sk || !sk_fullsock(sk) || ip_sk_use_pmtu(sk)) {
                bool forwarding = IPCB(skb)->flags & IPSKB_FORWARDED;
+
                return ip_dst_mtu_maybe_forward(skb_dst(skb), forwarding);
-       } else {
-               return min(skb_dst(skb)->dev->mtu, IP_MAX_MTU);
        }
+
+       return min(skb_dst(skb)->dev->mtu, IP_MAX_MTU);
 }
 
 u32 ip_idents_reserve(u32 hash, int segs);