Re: [PATCH V2 1/2] tty: serial: qcom_geni_serial: Allocate port->rx_fifo buffer in probe

[skakit@codeaurora.org]

On 2020-02-29 04:24, Stephen Boyd wrote:
> Quoting satya priya (2020-02-25 05:54:21)
>> To fix the RX cancel command failure, rx_fifo buffer needs to be
>> flushed in stop_rx() by calling handle_rx().
>> 
>> If set_termios is called before startup, by this time memory is not
>> allocated to port->rx_fifo buffer, which leads to a NULL pointer
>> dereference.
>> 
>> To avoid this NULL pointer dereference allocate memory to 
>> port->rx_fifo
>> in probe itself.
>> 
>> Signed-off-by: satya priya <skakit@codeaurora.org>
> 
> Please give me reported-by credit.
> 
> Reported-by: Stephen Boyd <swboyd@chromium.org>

Ok.

> 
>> ---
>>  drivers/tty/serial/qcom_geni_serial.c | 13 +++++++------
>>  1 file changed, 7 insertions(+), 6 deletions(-)
>> 
>> diff --git a/drivers/tty/serial/qcom_geni_serial.c 
>> b/drivers/tty/serial/qcom_geni_serial.c
>> index 191abb1..d2a909c 100644
>> --- a/drivers/tty/serial/qcom_geni_serial.c
>> +++ b/drivers/tty/serial/qcom_geni_serial.c
>> @@ -858,12 +858,6 @@ static int qcom_geni_serial_port_setup(struct 
>> uart_port *uport)
>>                                                 false, false, true);
>>         geni_se_init(&port->se, UART_RX_WM, port->rx_fifo_depth - 2);
>>         geni_se_select_mode(&port->se, GENI_SE_FIFO);
>> -       if (!uart_console(uport)) {
>> -               port->rx_fifo = devm_kcalloc(uport->dev,
>> -                       port->rx_fifo_depth, sizeof(u32), GFP_KERNEL);
>> -               if (!port->rx_fifo)
>> -                       return -ENOMEM;
>> -       }
>>         port->setup = true;
>> 
>>         return 0;
>> @@ -1274,6 +1268,13 @@ static int qcom_geni_serial_probe(struct 
>> platform_device *pdev)
>>         port->rx_fifo_depth = DEF_FIFO_DEPTH_WORDS;
>>         port->tx_fifo_width = DEF_FIFO_WIDTH_BITS;
>> 
>> +       if (!console) {
>> +               port->rx_fifo = devm_kcalloc(uport->dev,
>> +                       port->rx_fifo_depth, sizeof(u32), GFP_KERNEL);
>> +               if (!port->rx_fifo)
>> +                       return -ENOMEM;
>> +       }
> 
> Is there any reason the rx_fifo pointer is a u32 instead of a u8 or 
> void
> pointer? ioread32_rep() doesn't care what the pointer is and then we
> have to cast it, so it seems like we should do something like below 
> too.
> 

Yes, we can use void instead of u32, will add this change in next patch.

> -----8<-----
> 
> diff --git a/drivers/tty/serial/qcom_geni_serial.c
> b/drivers/tty/serial/qcom_geni_serial.c
> index 191abb18fc2a..b4875dfef6aa 100644
> --- a/drivers/tty/serial/qcom_geni_serial.c
> +++ b/drivers/tty/serial/qcom_geni_serial.c
> @@ -113,7 +113,7 @@ struct qcom_geni_serial_port {
>  	unsigned int baud;
>  	unsigned int tx_bytes_pw;
>  	unsigned int rx_bytes_pw;
> -	u32 *rx_fifo;
> +	u8 *rx_fifo;
>  	u32 loopback;
>  	bool brk;
> 
> @@ -504,7 +504,6 @@ static int handle_rx_console(struct uart_port
> *uport, u32 bytes, bool drop)
> 
>  static int handle_rx_uart(struct uart_port *uport, u32 bytes, bool 
> drop)
>  {
> -	unsigned char *buf;
>  	struct tty_port *tport;
>  	struct qcom_geni_serial_port *port = to_dev_port(uport, uport);
>  	u32 num_bytes_pw = port->tx_fifo_width / BITS_PER_BYTE;
> @@ -516,8 +515,7 @@ static int handle_rx_uart(struct uart_port *uport,
> u32 bytes, bool drop)
>  	if (drop)
>  		return 0;
> 
> -	buf = (unsigned char *)port->rx_fifo;
> -	ret = tty_insert_flip_string(tport, buf, bytes);
> +	ret = tty_insert_flip_string(tport, port->rx_fifo, bytes);
>  	if (ret != bytes) {
>  		dev_err(uport->dev, "%s:Unable to push data ret %d_bytes %d\n",
>  				__func__, ret, bytes);