Commit 4b390513 authored Feb 02, 2019 by Myungho Jung Committed by Greg Kroah-Hartman Mar 27, 2019

Bluetooth: Fix decrementing reference count twice in releasing socket



commit e20a2e9c42c9e4002d9e338d74e7819e88d77162 upstream.

When releasing socket, it is possible to enter hci_sock_release() and
hci_sock_dev_event(HCI_DEV_UNREG) at the same time in different thread.
The reference count of hdev should be decremented only once from one of
them but if storing hdev to local variable in hci_sock_release() before
detached from socket and setting to NULL in hci_sock_dev_event(),
hci_dev_put(hdev) is unexpectedly called twice. This is resolved by
referencing hdev from socket after bt_sock_unlink() in
hci_sock_release().

Reported-by:  <syzbot+fdc00003f4efff43bc5b@syzkaller.appspotmail.com>
Signed-off-by: Myungho Jung <mhjungk@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 4e0ca4bf

net/bluetooth/hci_sock.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -831,8 +831,6 @@ static int hci_sock_release(struct socket *sock)
		if (!sk)
		return 0;

		hdev = hci_pi(sk)->hdev;

		switch (hci_pi(sk)->channel) {
		case HCI_CHANNEL_MONITOR:
		atomic_dec(&monitor_promisc);
		@@ -854,6 +852,7 @@ static int hci_sock_release(struct socket *sock)

		bt_sock_unlink(&hci_sk_list, sk);

		hdev = hci_pi(sk)->hdev;
		if (hdev) {
		if (hci_pi(sk)->channel == HCI_CHANNEL_USER) {
		/* When releasing a user channel exclusive access,