From: Dan Carpenter dan.carpenter@oracle.com
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: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- 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 d4e2a16..e506c51 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; }