From c3658e8d0f10147fc86018be7f11668246c156d3 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 25 Nov 2014 07:40:04 -0800 Subject: [PATCH] tcp: fix possible NULL dereference in tcp_vX_send_reset() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Eric Dumazet Reported-by: Daniel Borkmann Fixes: ca777eff51f7 ("tcp: remove dst refcount false sharing for prequeue mode") Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 5 ++++- net/ipv6/tcp_ipv6.c | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) 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 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb) 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 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb) 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 -- 2.7.4