Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto()
authorKefeng Wang <wangkefeng.wang@huawei.com>
Sat, 23 Feb 2019 04:33:27 +0000 (12:33 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 27 Mar 2019 05:13:53 +0000 (14:13 +0900)
commit 56897b217a1d0a91c9920cb418d6b3fe922f590a upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/bluetooth/hci_ldisc.c

index 6a3a3011b38e5ab422b1d4cf1a234754b9187576..3b63a781f10fce4d293422102d5689b348e40389 100644 (file)
@@ -692,14 +692,13 @@ 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;
 }