4.20-stable review patch. If anyone has any objections, please let me know.
------------------
From: Cong Wang xiyou.wangcong@gmail.com
[ Upstream commit 7314f5480f3e37e570104dc5e0f28823ef849e72 ]
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netrom/af_netrom.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
--- a/net/netrom/af_netrom.c +++ b/net/netrom/af_netrom.c @@ -153,7 +153,7 @@ static struct sock *nr_find_listener(ax2 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(unsig 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(unsigne
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_circu 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, str }
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, str
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, str (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, str sk->sk_data_ready(sk);
bh_unlock_sock(sk); + sock_put(sk);
nr_insert_socket(make);