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>

2 files changed, 3 insertions, 3 deletions

diff --git a/net/vmw_vsock/vmci_transport_notify.c b/net/vmw_vsock/vmci_transport_notify.c
index 9a73074..9b7f207 100644
--- a/net/vmw_vsock/vmci_transport_notify.c
+++ b/net/vmw_vsock/vmci_transport_notify.c
@@ -315,7 +315,7 @@ vmci_transport_handle_wrote(struct sock *sk,
 	struct vsock_sock *vsk = vsock_sk(sk);
 	PKT_FIELD(vsk, sent_waiting_read) = false;
 #endif
-	sk->sk_data_ready(sk, 0);
+	sk->sk_data_ready(sk);
 }
 
 static void vmci_transport_notify_pkt_socket_init(struct sock *sk)
diff --git a/net/vmw_vsock/vmci_transport_notify_qstate.c b/net/vmw_vsock/vmci_transport_notify_qstate.c
index 622bd7a..dc9c792 100644
--- a/net/vmw_vsock/vmci_transport_notify_qstate.c
+++ b/net/vmw_vsock/vmci_transport_notify_qstate.c
@@ -92,7 +92,7 @@ vmci_transport_handle_wrote(struct sock *sk,
 			    bool bottom_half,
 			    struct sockaddr_vm *dst, struct sockaddr_vm *src)
 {
-	sk->sk_data_ready(sk, 0);
+	sk->sk_data_ready(sk);
 }
 
 static void vsock_block_update_write_window(struct sock *sk)
@@ -290,7 +290,7 @@ vmci_transport_notify_pkt_recv_post_dequeue(
 		/* See the comment in
 		 * vmci_transport_notify_pkt_send_post_enqueue().
 		 */
-		sk->sk_data_ready(sk, 0);
+		sk->sk_data_ready(sk);
 	}
 
 	return err;