Re: [PATCH 4.9/4.14/4.19/5.4] tty/serial: digicolor: fix possible null-ptr-deref in digicolor_uart_probe()

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, May 16, 2022 at 10:11:52PM +0800, Yang Yingliang wrote:
> commit 447ee1516f19f534a228dda237eddb202f23e163 upstream.
> 
> It will cause null-ptr-deref when using 'res', if platform_get_resource()
> returns NULL, so move using 'res' after devm_ioremap_resource() that
> will check it to avoid null-ptr-deref.
> And use devm_platform_get_and_ioremap_resource() to simplify code.
> 
> Fixes: 5930cb3511df ("serial: driver for Conexant Digicolor USART")
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> Reviewed-by: Baruch Siach <baruch@tkos.co.il>
> Cc: stable <stable@vger.kernel.org>
> Link: https://lore.kernel.org/r/20220505124621.1592697-1-yangyingliang@huawei.com
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> v1:
>   These stable versions don't have devm_platform_get_and_ioremap_resource(),
>   so just move using 'res' after devm_ioremap_resource().
> ---
>  drivers/tty/serial/digicolor-usart.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
> index 50ec5f1ac77f4..794864fac6250 100644
> --- a/drivers/tty/serial/digicolor-usart.c
> +++ b/drivers/tty/serial/digicolor-usart.c
> @@ -476,10 +476,10 @@ static int digicolor_uart_probe(struct platform_device *pdev)
>  		return PTR_ERR(uart_clk);
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	dp->port.mapbase = res->start;
>  	dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
>  	if (IS_ERR(dp->port.membase))
>  		return PTR_ERR(dp->port.membase);
> +	dp->port.mapbase = res->start;
>  
>  	irq = platform_get_irq(pdev, 0);
>  	if (irq < 0)
> -- 
> 2.25.1
> 

Now queued up, thanks.

greg k-h