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>

5 files changed, 13 insertions, 14 deletions

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 3190ca9..1e5b453 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -424,7 +424,7 @@ int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
 }
 
 /* Data available on socket or listen socket received a connect */
-static void lowcomms_data_ready(struct sock *sk, int count_unused)
+static void lowcomms_data_ready(struct sock *sk)
 {
 	struct connection *con = sock2con(sk);
 	if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
diff --git a/fs/ncpfs/ncp_fs_sb.h b/fs/ncpfs/ncp_fs_sb.h
index b81e97a..fbb0881 100644
--- a/fs/ncpfs/ncp_fs_sb.h
+++ b/fs/ncpfs/ncp_fs_sb.h
@@ -111,7 +111,7 @@ struct ncp_server {
 
 	spinlock_t requests_lock;	/* Lock accesses to tx.requests, tx.creq and rcv.creq when STREAM mode */
 
-	void (*data_ready)(struct sock* sk, int len);
+	void (*data_ready)(struct sock* sk);
 	void (*error_report)(struct sock* sk);
 	void (*write_space)(struct sock* sk);	/* STREAM mode only */
 	struct {
@@ -153,7 +153,7 @@ extern void ncp_tcp_tx_proc(struct work_struct *work);
 extern void ncpdgram_rcv_proc(struct work_struct *work);
 extern void ncpdgram_timeout_proc(struct work_struct *work);
 extern void ncpdgram_timeout_call(unsigned long server);
-extern void ncp_tcp_data_ready(struct sock* sk, int len);
+extern void ncp_tcp_data_ready(struct sock* sk);
 extern void ncp_tcp_write_space(struct sock* sk);
 extern void ncp_tcp_error_report(struct sock* sk);
 
diff --git a/fs/ncpfs/sock.c b/fs/ncpfs/sock.c
index 3a15872..652da0d 100644
--- a/fs/ncpfs/sock.c
+++ b/fs/ncpfs/sock.c
@@ -96,11 +96,11 @@ static void ncp_req_put(struct ncp_request_reply *req)
 		kfree(req);
 }
 
-void ncp_tcp_data_ready(struct sock *sk, int len)
+void ncp_tcp_data_ready(struct sock *sk)
 {
 	struct ncp_server *server = sk->sk_user_data;
 
-	server->data_ready(sk, len);
+	server->data_ready(sk);
 	schedule_work(&server->rcv.tq);
 }
 
diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index eb649d2..d857534 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)
diff --git a/fs/ocfs2/cluster/tcp_internal.h b/fs/ocfs2/cluster/tcp_internal.h
index 4cbcb65..dc024367 100644
--- a/fs/ocfs2/cluster/tcp_internal.h
+++ b/fs/ocfs2/cluster/tcp_internal.h
@@ -165,7 +165,7 @@ struct o2net_sock_container {
 
 	/* original handlers for the sockets */
 	void			(*sc_state_change)(struct sock *sk);
-	void			(*sc_data_ready)(struct sock *sk, int bytes);
+	void			(*sc_data_ready)(struct sock *sk);
 
 	u32			sc_msg_key;
 	u16			sc_msg_type;