Date:   Mon, 1 Apr 2019 14:35:40 -0700
From:   Matthias Kaehlcke <mka@chromium.org>
To:     Marcel Holtmann <marcel@holtmann.org>,
        Johan Hedberg <johan.hedberg@gmail.com>
Cc:     linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
        Balakrishna Godavarthi <bgodavar@codeaurora.org>,
        Hemantg <hemantg@codeaurora.org>,
        Rocky Liao <rjliao@codeaurora.org>
Subject: Re: [PATCH] Bluetooth: hci_qca: Fix crash with non-serdev devices
Message-ID: <20190401213540.GJ112750@google.com>
References: <CAG5bF+TCPc=m_O33RHXHrt34T1Dz1zHLSkXfpxAoOTmrffGJ7w@mail.gmail.com>
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Hi Marcel,

do you have any comments or can this fix be landed?

Thanks

Matthias

On Wed, Mar 13, 2019 at 04:52:19PM -0700, Matthias Kaehlcke wrote:
> qca_set_baudrate() calls serdev_device_wait_until_sent() assuming that
> the HCI is always associated with a serdev device. This isn't true for
> ROME controllers instantiated through ldisc, where the call causes a
> crash due to a NULL pointer dereferentiation. Only call the function
> when we have a serdev device. The timeout for ROME devices at the end
> of qca_set_baudrate() is long enough to be reasonably sure that the
> command was sent.
> 
> Fixes: fa9ad876b8e0 ("Bluetooth: hci_qca: Add support for Qualcomm
> Bluetooth chip wcn3990")
> Reported-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
> Reported-by: Rocky Liao <rjliao@codeaurora.org>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
>  drivers/bluetooth/hci_qca.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index 4ea995d610d2..714a6a16f9d5 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -1004,7 +1004,8 @@ static int qca_set_baudrate(struct hci_dev
> *hdev, uint8_t baudrate)
>  	while (!skb_queue_empty(&qca->txq))
>  		usleep_range(100, 200);
> 
> -	serdev_device_wait_until_sent(hu->serdev,
> +	if (hu->serdev)
> +		serdev_device_wait_until_sent(hu->serdev,
>  		      msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS));
> 
>  	/* Give the controller time to process the request */