From 11eb85ec42dc8c7a7ec519b90ccf2eeae9409de8 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Wed, 15 Jan 2020 20:49:04 +0300 Subject: [PATCH] Bluetooth: Fix race condition in hci_release_sock() Syzbot managed to trigger a use after free "KASAN: use-after-free Write in hci_sock_bind". I have reviewed the code manually and one possibly cause I have found is that we are not holding lock_sock(sk) when we do the hci_dev_put(hdev) in hci_sock_release(). My theory is that the bind and the release are racing against each other which results in this use after free. Reported-by: syzbot+eba992608adf3d796bcc@syzkaller.appspotmail.com Signed-off-by: Dan Carpenter Signed-off-by: Johan Hedberg --- net/bluetooth/hci_sock.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c index 5756b124c2cb..9c4a093f8960 100644 --- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -839,6 +839,8 @@ static int hci_sock_release(struct socket *sock) if (!sk) return 0; + lock_sock(sk); + switch (hci_pi(sk)->channel) { case HCI_CHANNEL_MONITOR: atomic_dec(&monitor_promisc); @@ -886,6 +888,7 @@ static int hci_sock_release(struct socket *sock) skb_queue_purge(&sk->sk_receive_queue); skb_queue_purge(&sk->sk_write_queue); + release_sock(sk); sock_put(sk); return 0; }