net: qrtr: fix memory leaks

Syzbot reported memory leak in qrtr. The problem was in unputted
struct sock. qrtr_local_enqueue() function calls qrtr_port_lookup()
which takes sock reference if port was found. Then there is the following
check:

if (!ipc || &ipc->sk == skb->sk) {
	...
	return -ENODEV;
}

Since we should drop the reference before returning from this function and
ipc can be non-NULL inside this if, we should add qrtr_port_put() inside
this if.

The similar corner case is in qrtr_endpoint_post() as Manivannan
reported. In case of sock_queue_rcv_skb() failure we need to put
port reference to avoid leaking struct sock pointer.

Fixes: e04df98a ("net: qrtr: Remove receive worker")
Fixes: bdabad3e ("net: Add Qualcomm IPC router")
Reported-and-tested-by: syzbot+35a511c72ea7356cdcf3@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/qrtr/qrtr.c

@@ -518,8 +518,10 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 		if (!ipc)
 			goto err;
 
-		if (sock_queue_rcv_skb(&ipc->sk, skb))
+		if (sock_queue_rcv_skb(&ipc->sk, skb)) {
+			qrtr_port_put(ipc);
 			goto err;
+		}
 
 		qrtr_port_put(ipc);
 	}
@@ -839,6 +841,8 @@ static int qrtr_local_enqueue(struct qrtr_node *node, struct sk_buff *skb,
 
 	ipc = qrtr_port_lookup(to->sq_port);
 	if (!ipc || &ipc->sk == skb->sk) { /* do not send to self */
+		if (ipc)
+			qrtr_port_put(ipc);
 		kfree_skb(skb);
 		return -ENODEV;
 	}