From 429b64a9eb90b22c5000d008763b4cabf0db4fb5 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Sat, 29 Dec 2018 13:56:38 -0800 Subject: netrom: fix locking in nr_find_socket() [ 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/netrom/af_netrom.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'net/netrom') diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c index ed212ffc1d9d..046ae1caecea 100644 --- 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++; @@ -918,6 +918,7 @@ 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) @@ -927,6 +928,7 @@ 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; } @@ -958,10 +960,12 @@ 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; @@ -1014,6 +1018,7 @@ 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); -- cgit v1.2.3