Re: [PATCH 3/4] drm/imx: fix -Wformat-truncation warning in imx_ldb_probe()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, May 23, 2024 at 06:51:08PM +0300, Jani Nikula wrote:
> Enabling -Wformat-truncation yields the following warning:
> 
> ../drivers/gpu/drm/imx/ipuv3/imx-ldb.c: In function ‘imx_ldb_probe’:
> ../drivers/gpu/drm/imx/ipuv3/imx-ldb.c:658:57: error: ‘_sel’ directive output may be truncated writing 4 bytes into a region of size between 3 and 13 [-Werror=format-truncation=]
>   658 |                 snprintf(clkname, sizeof(clkname), "di%d_sel", i);
>       |                                                         ^~~~
> ../drivers/gpu/drm/imx/ipuv3/imx-ldb.c:658:17: note: ‘snprintf’ output between 8 and 18 bytes into a destination of size 16
>   658 |                 snprintf(clkname, sizeof(clkname), "di%d_sel", i);
>       |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If only the compiler could count to three...

> 
> Silence the warning by checking the snprintf() return value.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> 
> ---
> 
> Cc: Philipp Zabel <p.zabel@pengutronix.de>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: imx@lists.linux.dev
> ---
>  drivers/gpu/drm/imx/ipuv3/imx-ldb.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/imx/ipuv3/imx-ldb.c b/drivers/gpu/drm/imx/ipuv3/imx-ldb.c
> index 71d70194fcbd..46f779fe60ee 100644
> --- a/drivers/gpu/drm/imx/ipuv3/imx-ldb.c
> +++ b/drivers/gpu/drm/imx/ipuv3/imx-ldb.c
> @@ -654,8 +654,12 @@ static int imx_ldb_probe(struct platform_device *pdev)
>  	 */
>  	for (i = 0; i < 4; i++) {
>  		char clkname[16];
> +		int len;
> +
> +		len = snprintf(clkname, sizeof(clkname), "di%d_sel", i);
> +		if (len >= sizeof(clkname))
> +			dev_err(dev, "clkname truncated\n");
>  
> -		snprintf(clkname, sizeof(clkname), "di%d_sel", i);
>  		imx_ldb->clk_sel[i] = devm_clk_get(imx_ldb->dev, clkname);
>  		if (IS_ERR(imx_ldb->clk_sel[i])) {
>  			ret = PTR_ERR(imx_ldb->clk_sel[i]);
> -- 
> 2.39.2

-- 
Ville Syrjälä
Intel