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Bluetooth: Fix race condition in hci_release_sock()

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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 <dan.carpenter@oracle.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
This commit is contained in:
Dan Carpenter 2020-01-15 20:49:04 +03:00 committed by Johan Hedberg
parent 18f81241b7
commit 11eb85ec42
1 changed files with 3 additions and 0 deletions
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3
net/bluetooth/hci_sock.c
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@ -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;
}