From a93d01f5777e99f24b5b3948e06673ada148337c Mon Sep 17 00:00:00 2001 From: Sowmini Varadhan Date: Thu, 14 Jul 2016 03:51:01 -0700 Subject: RDS: TCP: avoid bad page reference in rds_tcp_listen_data_ready As the existing comments in rds_tcp_listen_data_ready() indicate, it is possible under some race-windows to get to this function with the accept() socket. If that happens, we could run into a sequence whereby thread 1 thread 2 rds_tcp_accept_one() thread sets up new_sock via ->accept(). The sk_user_data is now sock_def_readable data comes in for new_sock, ->sk_data_ready is called, and we land in rds_tcp_listen_data_ready rds_tcp_set_callbacks() takes the sk_callback_lock and sets up sk_user_data to be the cp read_lock sk_callback_lock ready = cp unlock sk_callback_lock page fault on ready In the above sequence, we end up with a panic on a bad page reference when trying to execute (*ready)(). Instead we need to call sock_def_readable() safely, which is what this patch achieves. Acked-by: Santosh Shilimkar Signed-off-by: Sowmini Varadhan Signed-off-by: David S. Miller --- net/rds/tcp.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'net/rds/tcp.c') diff --git a/net/rds/tcp.c b/net/rds/tcp.c index d24f6c142d03..b411bb764f07 100644 --- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -551,6 +551,13 @@ static void rds_tcp_kill_sock(struct net *net) } } +void *rds_tcp_listen_sock_def_readable(struct net *net) +{ + struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid); + + return rtn->rds_tcp_listen_sock->sk->sk_user_data; +} + static int rds_tcp_dev_event(struct notifier_block *this, unsigned long event, void *ptr) { -- cgit v1.2.3