Re: [PATCH] staging: fbtft: Fix buffer overflow vulnerability

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Feb 15, 2017 at 11:42:54AM +1100, Tobin C. Harding wrote:
> Module copies a user supplied string (module parameter) into a buffer
> using strncpy() and does not check that the buffer is null terminated.
> 
> Replace call to strncpy() with call to strlcpy() ensuring that the
> buffer is null terminated.
> 
> Signed-off-by: Tobin C. Harding <me@tobin.cc>
> ---
>  drivers/staging/fbtft/fbtft_device.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/fbtft/fbtft_device.c b/drivers/staging/fbtft/fbtft_device.c
> index de46f8d..7b7223b 100644
> --- a/drivers/staging/fbtft/fbtft_device.c
> +++ b/drivers/staging/fbtft/fbtft_device.c
> @@ -1483,7 +1483,7 @@ static int __init fbtft_device_init(void)
>  			displays[i].pdev->name = name;
>  			displays[i].spi = NULL;
>  		} else {
> -			strncpy(displays[i].spi->modalias, name, SPI_NAME_SIZE);
> +			strlcpy(displays[i].spi->modalias, name, SPI_NAME_SIZE);

Shouldn't we properly check the return value here to know if the buffer
did get truncated?  Or do we really care?

thanks,

greg k-h