blob: 7d54949c377835eb39bea0c81d846995f4caa6b9 [file] [log] [blame]
From cbd7ef980dc3b20278d2925343d6ac486d8f0c3c Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Wed, 15 Jan 2020 20:49:04 +0300
Subject: [PATCH] Bluetooth: Fix race condition in hci_release_sock()
commit 11eb85ec42dc8c7a7ec519b90ccf2eeae9409de8 upstream.
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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index d32077b28433..8159b344deef 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;
}
--
2.7.4