Commit 56897b21 authored Feb 23, 2019 by Kefeng Wang Committed by Marcel Holtmann Feb 26, 2019

Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto()



task A:                                task B:
hci_uart_set_proto                     flush_to_ldisc
 - p->open(hu) -> h5_open  //alloc h5  - receive_buf
 - set_bit HCI_UART_PROTO_READY         - tty_port_default_receive_buf
 - hci_uart_register_dev                 - tty_ldisc_receive_buf
                                          - hci_uart_tty_receive
				           - test_bit HCI_UART_PROTO_READY
				            - h5_recv
 - clear_bit HCI_UART_PROTO_READY             while() {
 - p->open(hu) -> h5_close //free h5
				              - h5_rx_3wire_hdr
				               - h5_reset()  //use-after-free
                                              }

It could use ioctl to set hci uart proto, but there is
a use-after-free issue when hci_uart_register_dev() fail in
hci_uart_set_proto(), see stack above, fix this by setting
HCI_UART_PROTO_READY bit only when hci_uart_register_dev()
return success.

Reported-by:  <syzbot+899a33dc0fa0dbaf06a6@syzkaller.appspotmail.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Jeremy Cline <jcline@redhat.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

parent 4a67e5d4

drivers/bluetooth/hci_ldisc.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -696,14 +696,13 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
		return -EPROTONOSUPPORT;

		hu->proto = p;
		set_bit(HCI_UART_PROTO_READY, &hu->flags);

		err = hci_uart_register_dev(hu);
		if (err) {
		clear_bit(HCI_UART_PROTO_READY, &hu->flags);
		return err;
		}

		set_bit(HCI_UART_PROTO_READY, &hu->flags);
		return 0;
		}