Re: [PATCH v5.3-rc2] Bluetooth: hci_uart: check for missing tty operations

[Al Cho <ACho@suse.com>]

On Tue, 2019-07-30 at 11:33 +0200, Marcel Holtmann wrote:
> From: Vladis Dronov <vdronov@redhat.com>
> 
> Certain ttys operations (pty_unix98_ops) lack tiocmget() and
> tiocmset()
> functions which are called by the certain HCI UART protocols
> (hci_ath,
> hci_bcm, hci_intel, hci_mrvl, hci_qca) via
> hci_uart_set_flow_control()
> or directly. This leads to an execution at NULL and can be triggered
> by
> an unprivileged user. Fix this by adding a helper function and a
> check
> for the missing tty operations in the protocols code.
> 
> This fixes CVE-2019-10207. The Fixes: lines list commits where calls
> to
> tiocm[gs]et() or hci_uart_set_flow_control() were added to the HCI
> UART
> protocols.
> 
> Link: 
> https://syzkaller.appspot.com/bug?id=1b42faa2848963564a5b1b7f8c837ea7b55ffa50
> Reported-by: syzbot+79337b501d6aa974d0f6@syzkaller.appspotmail.com
> Cc: stable@vger.kernel.org # v2.6.36+
> Fixes: b3190df62861 ("Bluetooth: Support for Atheros AR300x serial
> chip")
> Fixes: 118612fb9165 ("Bluetooth: hci_bcm: Add suspend/resume PM
> functions")
> Fixes: ff2895592f0f ("Bluetooth: hci_intel: Add Intel baudrate
> configuration support")
> Fixes: 162f812f23ba ("Bluetooth: hci_uart: Add Marvell support")
> Fixes: fa9ad876b8e0 ("Bluetooth: hci_qca: Add support for Qualcomm
> Bluetooth chip wcn3990")
> Signed-off-by: Vladis Dronov <vdronov@redhat.com>
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Reviewed-by: Yu-Chen, Cho <acho@suse.com>
Tested-by: Yu-Chen, Cho <acho@suse.com>

> ---
>  drivers/bluetooth/hci_ath.c   |  3 +++
>  drivers/bluetooth/hci_bcm.c   |  3 +++
>  drivers/bluetooth/hci_intel.c |  3 +++
>  drivers/bluetooth/hci_ldisc.c | 13 +++++++++++++
>  drivers/bluetooth/hci_mrvl.c  |  3 +++
>  drivers/bluetooth/hci_qca.c   |  3 +++
>  drivers/bluetooth/hci_uart.h  |  1 +
>  7 files changed, 29 insertions(+)
> 
> diff --git a/drivers/bluetooth/hci_ath.c
> b/drivers/bluetooth/hci_ath.c
> index a55be205b91a..dbfe34664633 100644
> --- a/drivers/bluetooth/hci_ath.c
> +++ b/drivers/bluetooth/hci_ath.c
> @@ -98,6 +98,9 @@ static int ath_open(struct hci_uart *hu)
>  
>  	BT_DBG("hu %p", hu);
>  
> +	if (!hci_uart_has_flow_control(hu))
> +		return -EOPNOTSUPP;
> +
>  	ath = kzalloc(sizeof(*ath), GFP_KERNEL);
>  	if (!ath)
>  		return -ENOMEM;
> diff --git a/drivers/bluetooth/hci_bcm.c
> b/drivers/bluetooth/hci_bcm.c
> index 8905ad2edde7..ae2624fce913 100644
> --- a/drivers/bluetooth/hci_bcm.c
> +++ b/drivers/bluetooth/hci_bcm.c
> @@ -406,6 +406,9 @@ static int bcm_open(struct hci_uart *hu)
>  
>  	bt_dev_dbg(hu->hdev, "hu %p", hu);
>  
> +	if (!hci_uart_has_flow_control(hu))
> +		return -EOPNOTSUPP;
> +
>  	bcm = kzalloc(sizeof(*bcm), GFP_KERNEL);
>  	if (!bcm)
>  		return -ENOMEM;
> diff --git a/drivers/bluetooth/hci_intel.c
> b/drivers/bluetooth/hci_intel.c
> index 207bae5e0d46..31f25153087d 100644
> --- a/drivers/bluetooth/hci_intel.c
> +++ b/drivers/bluetooth/hci_intel.c
> @@ -391,6 +391,9 @@ static int intel_open(struct hci_uart *hu)
>  
>  	BT_DBG("hu %p", hu);
>  
> +	if (!hci_uart_has_flow_control(hu))
> +		return -EOPNOTSUPP;
> +
>  	intel = kzalloc(sizeof(*intel), GFP_KERNEL);
>  	if (!intel)
>  		return -ENOMEM;
> diff --git a/drivers/bluetooth/hci_ldisc.c
> b/drivers/bluetooth/hci_ldisc.c
> index 8950e07889fe..85a30fb9177b 100644
> --- a/drivers/bluetooth/hci_ldisc.c
> +++ b/drivers/bluetooth/hci_ldisc.c
> @@ -292,6 +292,19 @@ static int hci_uart_send_frame(struct hci_dev
> *hdev, struct sk_buff *skb)
>  	return 0;
>  }
>  
> +/* Check the underlying device or tty has flow control support */
> +bool hci_uart_has_flow_control(struct hci_uart *hu)
> +{
> +	/* serdev nodes check if the needed operations are present */
> +	if (hu->serdev)
> +		return true;
> +
> +	if (hu->tty->driver->ops->tiocmget && hu->tty->driver->ops-
> >tiocmset)
> +		return true;
> +
> +	return false;
> +}
> +
>  /* Flow control or un-flow control the device */
>  void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
>  {
> diff --git a/drivers/bluetooth/hci_mrvl.c
> b/drivers/bluetooth/hci_mrvl.c
> index f98e5cc343b2..fbc3f7c3a5c7 100644
> --- a/drivers/bluetooth/hci_mrvl.c
> +++ b/drivers/bluetooth/hci_mrvl.c
> @@ -59,6 +59,9 @@ static int mrvl_open(struct hci_uart *hu)
>  
>  	BT_DBG("hu %p", hu);
>  
> +	if (!hci_uart_has_flow_control(hu))
> +		return -EOPNOTSUPP;
> +
>  	mrvl = kzalloc(sizeof(*mrvl), GFP_KERNEL);
>  	if (!mrvl)
>  		return -ENOMEM;
> diff --git a/drivers/bluetooth/hci_qca.c
> b/drivers/bluetooth/hci_qca.c
> index 9a5c9c1f9484..82a0a3691a63 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -473,6 +473,9 @@ static int qca_open(struct hci_uart *hu)
>  
>  	BT_DBG("hu %p qca_open", hu);
>  
> +	if (!hci_uart_has_flow_control(hu))
> +		return -EOPNOTSUPP;
> +
>  	qca = kzalloc(sizeof(struct qca_data), GFP_KERNEL);
>  	if (!qca)
>  		return -ENOMEM;
> diff --git a/drivers/bluetooth/hci_uart.h
> b/drivers/bluetooth/hci_uart.h
> index f11af3912ce6..6ab631101019 100644
> --- a/drivers/bluetooth/hci_uart.h
> +++ b/drivers/bluetooth/hci_uart.h
> @@ -104,6 +104,7 @@ int hci_uart_wait_until_sent(struct hci_uart
> *hu);
>  int hci_uart_init_ready(struct hci_uart *hu);
>  void hci_uart_init_work(struct work_struct *work);
>  void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed);
> +bool hci_uart_has_flow_control(struct hci_uart *hu);
>  void hci_uart_set_flow_control(struct hci_uart *hu, bool enable);
>  void hci_uart_set_speeds(struct hci_uart *hu, unsigned int
> init_speed,
>  			 unsigned int oper_speed);