linux-kernel - Re: [PATCH] media: omap3isp: fix out-of-range warning

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Message-ID: <YZ68G09viJA/vkby@pendragon.ideasonboard.com>
Date:   Thu, 25 Nov 2021 00:26:35 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Vaibhav Hiremath <hvaibhav@...com>,
        Stanimir Varbanov <svarbanov@...sol.com>,
        Dominic Curran <dcurran@...com>,
        David Cohen <dacohen@...il.com>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] media: omap3isp: fix out-of-range warning

Hi Arnd,

Thank you for the patch.

On Wed, Nov 24, 2021 at 08:24:15PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> clang points out that the 8-bit height/width values never exceed
> the range of that type when building with 'make W=1 LLVM=1':
> 
> drivers/media/platform/omap3isp/isph3a_af.c:173:6: error: result of comparison of constant 256 with expression of type '__u8' (aka 'unsigned char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>         if (IS_OUT_OF_BOUNDS(paxel_cfg->height, OMAP3ISP_AF_PAXEL_HEIGHT_MIN,
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/media/platform/omap3isp/isph3a_af.c:24:33: note: expanded from macro 'IS_OUT_OF_BOUNDS'
>         (((value) < (min)) || ((value) > (max)))
>                                ~~~~~~~ ^ ~~~~~
> drivers/media/platform/omap3isp/isph3a_af.c:179:6: error: result of comparison of constant 256 with expression of type '__u8' (aka 'unsigned char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>         if (IS_OUT_OF_BOUNDS(paxel_cfg->width, OMAP3ISP_AF_PAXEL_WIDTH_MIN,
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/media/platform/omap3isp/isph3a_af.c:24:33: note: expanded from macro 'IS_OUT_OF_BOUNDS'
>         (((value) < (min)) || ((value) > (max)))
>                                ~~~~~~~ ^ ~~~~~
> 
> Add a cast to 32-bit to avoid the warning. Checking just the lower bounds
> would be sufficient as well, but it seems more consistent to use
> the IS_OUT_OF_BOUNDS() check for all members.

Mauro has submitted a fix that handles the cast in the
IS_OUT_OF_BOUNDS() macro, see
https://lore.kernel.org/all/b70f819b11e024649f113be1158f34b24914a1ed.1637573097.git.mchehab+huawei@kernel.org/.

> Fixes: 68e342b3068c ("[media] omap3isp: Statistics")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/media/platform/omap3isp/isph3a_af.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/omap3isp/isph3a_af.c b/drivers/media/platform/omap3isp/isph3a_af.c
> index a65cfdfa9637..c544d9c812b0 100644
> --- a/drivers/media/platform/omap3isp/isph3a_af.c
> +++ b/drivers/media/platform/omap3isp/isph3a_af.c
> @@ -170,13 +170,13 @@ static int h3a_af_validate_params(struct ispstat *af, void *new_conf)
>  			     OMAP3ISP_AF_PAXEL_VERTICAL_COUNT_MAX))
>  		return -EINVAL;
>  
> -	if (IS_OUT_OF_BOUNDS(paxel_cfg->height, OMAP3ISP_AF_PAXEL_HEIGHT_MIN,
> +	if (IS_OUT_OF_BOUNDS((u32)paxel_cfg->height, OMAP3ISP_AF_PAXEL_HEIGHT_MIN,
>  			     OMAP3ISP_AF_PAXEL_HEIGHT_MAX) ||
>  	    paxel_cfg->height % 2)
>  		return -EINVAL;
>  
>  	/* Check width */
> -	if (IS_OUT_OF_BOUNDS(paxel_cfg->width, OMAP3ISP_AF_PAXEL_WIDTH_MIN,
> +	if (IS_OUT_OF_BOUNDS((u32)paxel_cfg->width, OMAP3ISP_AF_PAXEL_WIDTH_MIN,
>  			     OMAP3ISP_AF_PAXEL_WIDTH_MAX) ||
>  	    paxel_cfg->width % 2)
>  		return -EINVAL;

-- 
Regards,

Laurent Pinchart