linux-kernel - Re: [PATCH 10/18] tty: serial: samsung: make max

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Message-ID: <b21a54a7-fe13-4a29-8e7e-6b653d5c24ef@linaro.org>
Date: Wed, 17 Jan 2024 15:21:04 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Sam Protsenko <semen.protsenko@...aro.org>
Cc: krzysztof.kozlowski@...aro.org, alim.akhtar@...sung.com,
 gregkh@...uxfoundation.org, jirislaby@...nel.org,
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
 andre.draszik@...aro.org, peter.griffin@...aro.org, kernel-team@...roid.com,
 willmcvicker@...gle.com
Subject: Re: [PATCH 10/18] tty: serial: samsung: make max_count unsigned int



On 1/16/24 18:21, Sam Protsenko wrote:
> On Wed, Jan 10, 2024 at 4:23 AM Tudor Ambarus <tudor.ambarus@...aro.org> wrote:
>>
>> ``max_count`` negative values are not used. Since ``port->fifosize``
>> is an unsigned int, make ``max_count`` the same.
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
>> ---
>>  drivers/tty/serial/samsung_tty.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
>> index 90c49197efc7..dbbe6b8e3ceb 100644
>> --- a/drivers/tty/serial/samsung_tty.c
>> +++ b/drivers/tty/serial/samsung_tty.c
>> @@ -760,8 +760,8 @@ static irqreturn_t s3c24xx_serial_rx_chars_dma(void *dev_id)
>>  static void s3c24xx_serial_rx_drain_fifo(struct s3c24xx_uart_port *ourport)
>>  {
>>         struct uart_port *port = &ourport->port;
>> +       unsigned int max_count = port->fifosize;
> 
> What if port->fifosize is 0? Then this code below:
> 
>     while (max_count-- > 0) {
> 
> would cause int overflow, if max_count is unsigned?
> 

good catch, Sam!

I'm thinking of amending this and add at the beginning of the method:

if (!max_count)
	return tty_flip_buffer_push(&port->state->port);

Thanks!
ta