Received-SPF: pass (google.com: domain of linux-kernel+bounces-29149-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Message-ID: <b21a54a7-fe13-4a29-8e7e-6b653d5c24ef@linaro.org>
Date: Wed, 17 Jan 2024 15:21:04 +0000
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 10/18] tty: serial: samsung: make max_count unsigned int
Content-Language: en-US
To: Sam Protsenko <semen.protsenko@linaro.org>
Cc: krzysztof.kozlowski@linaro.org, alim.akhtar@samsung.com,
 gregkh@linuxfoundation.org, jirislaby@kernel.org,
 linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
 andre.draszik@linaro.org, peter.griffin@linaro.org, kernel-team@android.com,
 willmcvicker@google.com
References: <20240110102102.61587-1-tudor.ambarus@linaro.org>
 <20240110102102.61587-11-tudor.ambarus@linaro.org>
 <CAPLW+4=YYdUSaaLcsdEyPswC4s6onxuSh24vSfw4xys=sPZG_Q@mail.gmail.com>
From: Tudor Ambarus <tudor.ambarus@linaro.org>
In-Reply-To: <CAPLW+4=YYdUSaaLcsdEyPswC4s6onxuSh24vSfw4xys=sPZG_Q@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit


On 1/16/24 18:21, Sam Protsenko wrote:
> On Wed, Jan 10, 2024 at 4:23 AM Tudor Ambarus <tudor.ambarus@linaro.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@linaro.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