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

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Date: Tue, 16 Jan 2024 12:21:25 -0600
From: Sam Protsenko <semen.protsenko@...aro.org>
To: Tudor Ambarus <tudor.ambarus@...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 Wed, Jan 10, 2024 at 4:23 AM Tudor Ambarus <tudor.ambarus@...aroorg> 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?

>         unsigned int fifocnt = 0;
> -       int max_count = port->fifosize;
>         u32 ufcon, ufstat, uerstat;
>         u8 ch, flag;
>
> --
> 2.43.0.472.g3155946c3a-goog
>
>