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    Subject[PATCH 5.0 40/52] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto()
    Date
    5.0-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Kefeng Wang <wangkefeng.wang@huawei.com>

    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 | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    --- a/drivers/bluetooth/hci_ldisc.c
    +++ b/drivers/bluetooth/hci_ldisc.c
    @@ -696,14 +696,13 @@ static int hci_uart_set_proto(struct hci
    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;
    }


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