ipv4: use sk_fullsock() in ipv4_conntrack_defrag()

Before converting a 'socket pointer' into inet socket,
use sk_fullsock() to detect timewait or request sockets.

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 3 deletions

diff --git a/net/ipv4/netfilter/nf_defrag_ipv4.c b/net/ipv4/netfilter/nf_defrag_ipv4.c
index 0e5591c2ee9f..6fb869f646bf 100644
--- a/net/ipv4/netfilter/nf_defrag_ipv4.c
+++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
@@ -67,10 +67,9 @@ static unsigned int ipv4_conntrack_defrag(void *priv,
                                           const struct nf_hook_state *state)
 {
         struct sock *sk = skb->sk;
-        struct inet_sock *inet = inet_sk(skb->sk);
 
-        if (sk && (sk->sk_family == PF_INET) &&
-            inet->nodefrag)
+        if (sk && sk_fullsock(sk) && (sk->sk_family == PF_INET) &&
+            inet_sk(sk)->nodefrag)
                 return NF_ACCEPT;
 
 #if IS_ENABLED(CONFIG_NF_CONNTRACK)