linux-kernel - Re: [PATCH drm-next] drm/bridge: it6505: Fix unreachable loop increment in KSV list check

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Message-ID: <qsylng4kkrosvdikotdiwsuppanlmg5kzmj6kkubx7wknuevit@d5rrej473gd4>
Date: Wed, 8 Jan 2025 04:08:05 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Dheeraj Reddy Jonnalagadda <dheeraj.linuxdev@...il.com>
Cc: andrzej.hajda@...el.com, neil.armstrong@...aro.org, rfoss@...nel.org, 
	Laurent.pinchart@...asonboard.com, jonas@...boo.se, jernej.skrabec@...il.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, 
	simona@...ll.ch, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH drm-next] drm/bridge: it6505: Fix unreachable loop
 increment in KSV list check

On Tue, Jan 07, 2025 at 04:37:40PM +0530, Dheeraj Reddy Jonnalagadda wrote:
> The inner loop in it6505_hdcp_part2_ksvlist_check had an unreachable
> increment due to returning true before the loop could continue.
> Restructure the loop to only return after verifying all 5 entries
> match, making the loop increment reachable.
> 
> Fixes: 0989c02c7a5c ("drm/bridge: it6505: fix HDCP CTS compare V matching")
> Closes: https://scan7.scan.coverity.com/#/project-view/52337/11354?selectedIssue=1602785
> Signed-off-by: Dheeraj Reddy Jonnalagadda <dheeraj.linuxdev@...il.com>
> ---
>  drivers/gpu/drm/bridge/ite-it6505.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 88ef76a37fe6..2ff2245abdeb 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -2255,8 +2255,10 @@ static bool it6505_hdcp_part2_ksvlist_check(struct it6505 *it6505)
>  			    av[i][1] != av[i][2] || bv[i][0] != av[i][3])
>  				break;
>  
> -			DRM_DEV_DEBUG_DRIVER(dev, "V' all match!! %d, %d", retry, i);
> -			return true;
> +			if (i == 4) {
> +				DRM_DEV_DEBUG_DRIVER(dev, "V' all match!! %d, %d", retry, i);
> +				return true;
> +			}

I think, it's more idiomatic if you move it out of the loop.

>  		}
>  	}
>  
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry