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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
Not tested! Please review very very carefully!
I feel like maybe someone should audit the (struct proto_ops)->release()
functions because there may be similar bugs to this in other drivers.
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 5d0ed28c0d3a..c86598ff4283 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -831,6 +831,8 @@ 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);
@@ -878,6 +880,7 @@ 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;
}
--
2.11.0
