netrom: fix locking in nr_find_socket()

nr_find_socket(), nr_find_peer() and nr_find_listener() lock the sock after finding it in the global list. However, the call path requires BH disabled for the sock lock consistently. Actually the locking is unnecessary at this point, we can just hold the sock refcnt to make sure it is not gone after we unlock the global list, and lock it later only when needed. Reported-and-tested-by: [email protected] Signed-off-by: Cong Wang <[email protected]> Signed-off-by: David S. Miller <[email protected]>
bignaux · Dec 31, 2018 · 7314f54 · 7314f54
1 parent d5c7c74
commit 7314f54
Showing 1 changed file with 10 additions and 5 deletions.
diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
@@ -153,7 +153,7 @@ static struct sock *nr_find_listener(ax25_address *addr)
 	sk_for_each(s, &nr_list)
 		if (!ax25cmp(&nr_sk(s)->source_addr, addr) &&
 		    s->sk_state == TCP_LISTEN) {
-			bh_lock_sock(s);
+			sock_hold(s);
 			goto found;
 		}
 	s = NULL;
@@ -174,7 +174,7 @@ static struct sock *nr_find_socket(unsigned char index, unsigned char id)
 		struct nr_sock *nr = nr_sk(s);
 
 		if (nr->my_index == index && nr->my_id == id) {
-			bh_lock_sock(s);
+			sock_hold(s);
 			goto found;
 		}
 	}
@@ -198,7 +198,7 @@ static struct sock *nr_find_peer(unsigned char index, unsigned char id,
 
 		if (nr->your_index == index && nr->your_id == id &&
 		    !ax25cmp(&nr->dest_addr, dest)) {
-			bh_lock_sock(s);
+			sock_hold(s);
 			goto found;
 		}
 	}
@@ -224,7 +224,7 @@ static unsigned short nr_find_next_circuit(void)
 		if (i != 0 && j != 0) {
 			if ((sk=nr_find_socket(i, j)) == NULL)
 				break;
-			bh_unlock_sock(sk);
+			sock_put(sk);
 		}
 
 		id++;
@@ -920,6 +920,7 @@ int nr_rx_frame(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	if (sk != NULL) {
+		bh_lock_sock(sk);
 		skb_reset_transport_header(skb);
 
 		if (frametype == NR_CONNACK && skb->len == 22)
@@ -929,6 +930,7 @@ int nr_rx_frame(struct sk_buff *skb, struct net_device *dev)
 
 		ret = nr_process_rx_frame(sk, skb);
 		bh_unlock_sock(sk);
+		sock_put(sk);
 		return ret;
 	}
 
@@ -960,10 +962,12 @@ int nr_rx_frame(struct sk_buff *skb, struct net_device *dev)
 	    (make = nr_make_new(sk)) == NULL) {
 		nr_transmit_refusal(skb, 0);
 		if (sk)
-			bh_unlock_sock(sk);
+			sock_put(sk);
 		return 0;
 	}
 
+	bh_lock_sock(sk);
+
 	window = skb->data[20];
 
 	skb->sk             = make;
@@ -1016,6 +1020,7 @@ int nr_rx_frame(struct sk_buff *skb, struct net_device *dev)
 		sk->sk_data_ready(sk);
 
 	bh_unlock_sock(sk);
+	sock_put(sk);
 
 	nr_insert_socket(make);