ipv6: NULL pointer dereferrence in tcp_v6_send_ack
The following actions are possible:
tcp_v6_rcv
skb->dev = NULL;
tcp_v6_do_rcv
tcp_v6_hnd_req
tcp_check_req
req->rsk_ops->send_ack == tcp_v6_send_ack
So, skb->dev can be NULL in tcp_v6_send_ack. We must obtain namespace
from dst entry.
Thanks to Vitaliy Gusev <vgusev@openvz.org> for initial problem finding
in IPv4 code.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index b585c85..10e22fd 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1050,7 +1050,7 @@
struct tcphdr *th = tcp_hdr(skb), *t1;
struct sk_buff *buff;
struct flowi fl;
- struct net *net = dev_net(skb->dev);
+ struct net *net = dev_net(skb->dst->dev);
struct sock *ctl_sk = net->ipv6.tcp_sk;
unsigned int tot_len = sizeof(struct tcphdr);
__be32 *topt;