linux-kernel - Re: [PATCH] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set

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Date:   Tue, 26 Feb 2019 09:56:31 +0100
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     "open list:BLUETOOTH DRIVERS" <linux-bluetooth@...r.kernel.org>,
        linux-kernel@...r.kernel.org, Jeremy Cline <jcline@...hat.com>,
        Johan Hedberg <johan.hedberg@...il.com>,
        syzbot+899a33dc0fa0dbaf06a6@...kaller.appspotmail.com
Subject: Re: [PATCH] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit
 set in hci_uart_set_proto()

Hi Kefeng,

> 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@...kaller.appspotmail.com
> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> ---
> drivers/bluetooth/hci_ldisc.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel