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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: syzbot+f621cda8b7e598908efa@syzkaller.appspotmail.com
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Cong Wang 2018-12-29 13:56:38 -08:00 committed by David S. Miller
parent d5c7c745f2
commit 7314f5480f
1 changed files with 10 additions and 5 deletions
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15
net/netrom/af_netrom.c
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@ -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);