net: Fix use after free by removing length arg from sk_data_ready callbacks.

Several spots in the kernel perform a sequence like:

	skb_queue_tail(&sk->s_receive_queue, skb);
	sk->sk_data_ready(sk, skb->len);

But at the moment we place the SKB onto the socket receive queue it
can be consumed and freed up.  So this skb->len access is potentially
to freed up memory.

Furthermore, the skb->len can be modified by the consumer so it is
possible that the value isn't accurate.

And finally, no actual implementation of this callback actually uses
the length argument.  And since nobody actually cared about it's
value, lots of call sites pass arbitrary values in such as '0' and
even '1'.

So just remove the length argument from the callback, that way there
is no confusion whatsoever and all of these use-after-free cases get
fixed as a side effect.

Based upon a patch by Eric Dumazet and his suggestion to audit this
issue tree-wide.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 8 deletions

diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index eb649d23a4de..d857534b886e 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -137,7 +137,7 @@ static int o2net_sys_err_translations[O2NET_ERR_MAX] =
 static void o2net_sc_connect_completed(struct work_struct *work);
 static void o2net_rx_until_empty(struct work_struct *work);
 static void o2net_shutdown_sc(struct work_struct *work);
-static void o2net_listen_data_ready(struct sock *sk, int bytes);
+static void o2net_listen_data_ready(struct sock *sk);
 static void o2net_sc_send_keep_req(struct work_struct *work);
 static void o2net_idle_timer(unsigned long data);
 static void o2net_sc_postpone_idle(struct o2net_sock_container *sc);
@@ -597,9 +597,9 @@ static void o2net_set_nn_state(struct o2net_node *nn,
 }
 
 /* see o2net_register_callbacks() */
-static void o2net_data_ready(struct sock *sk, int bytes)
+static void o2net_data_ready(struct sock *sk)
 {
-	void (*ready)(struct sock *sk, int bytes);
+	void (*ready)(struct sock *sk);
 
 	read_lock(&sk->sk_callback_lock);
 	if (sk->sk_user_data) {
@@ -613,7 +613,7 @@ static void o2net_data_ready(struct sock *sk, int bytes)
 	}
 	read_unlock(&sk->sk_callback_lock);
 
-	ready(sk, bytes);
+	ready(sk);
 }
 
 /* see o2net_register_callbacks() */
@@ -1953,9 +1953,9 @@ static void o2net_accept_many(struct work_struct *work)
 		cond_resched();
 }
 
-static void o2net_listen_data_ready(struct sock *sk, int bytes)
+static void o2net_listen_data_ready(struct sock *sk)
 {
-	void (*ready)(struct sock *sk, int bytes);
+	void (*ready)(struct sock *sk);
 
 	read_lock(&sk->sk_callback_lock);
 	ready = sk->sk_user_data;
@@ -1978,7 +1978,6 @@ static void o2net_listen_data_ready(struct sock *sk, int bytes)
 	 */
 
 	if (sk->sk_state == TCP_LISTEN) {
-		mlog(ML_TCP, "bytes: %d\n", bytes);
 		queue_work(o2net_wq, &o2net_listen_work);
 	} else {
 		ready = NULL;
@@ -1987,7 +1986,7 @@ static void o2net_listen_data_ready(struct sock *sk, int bytes)
 out:
 	read_unlock(&sk->sk_callback_lock);
 	if (ready != NULL)
-		ready(sk, bytes);
+		ready(sk);
 }
 
 static int o2net_open_listening_sock(__be32 addr, __be16 port)