tcp: fix possible NULL dereference in tcp_vX_send_reset()
After commit ca777eff51f7 ("tcp: remove dst refcount false sharing for
prequeue mode") we have to relax check against skb dst in
tcp_v[46]_send_reset() if prequeue dropped the dst.
If a socket is provided, a full lookup was done to find this socket,
so the dst test can be skipped.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88191
Reported-by: Jaša Bartelj <jasa.bartelj@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Daniel Borkmann <dborkman@redhat.com>
Fixes: ca777eff51f7 ("tcp: remove dst refcount false sharing for prequeue mode")
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 9c7d762..147be20 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -598,7 +598,10 @@
if (th->rst)
return;
- if (skb_rtable(skb)->rt_type != RTN_LOCAL)
+ /* If sk not NULL, it means we did a successful lookup and incoming
+ * route had to be correct. prequeue might have dropped our dst.
+ */
+ if (!sk && skb_rtable(skb)->rt_type != RTN_LOCAL)
return;
/* Swap the send and the receive. */
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index ace29b6..dc495ae 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -903,7 +903,10 @@
if (th->rst)
return;
- if (!ipv6_unicast_destination(skb))
+ /* If sk not NULL, it means we did a successful lookup and incoming
+ * route had to be correct. prequeue might have dropped our dst.
+ */
+ if (!sk && !ipv6_unicast_destination(skb))
return;
#ifdef CONFIG_TCP_MD5SIG