Re: [PATCH] drm/komeda: Fix bit check to import to value of proper type

From: Liviu Dudau <liviu.dudau@arm.com>
To: carsten.haitzler@foss.arm.com
Cc: Carsten Haitzler <carsten.haitzler@arm.com>,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/komeda: Fix bit check to import to value of proper type
Date: Fri, 18 Dec 2020 16:08:14 +0000	[thread overview]
Message-ID: <X9zT7q0FzC+DBJpU@e110455-lin.cambridge.arm.com> (raw)
In-Reply-To: <20201218150812.68195-1-carsten.haitzler@foss.arm.com>

On Fri, Dec 18, 2020 at 03:08:12PM +0000, carsten.haitzler@foss.arm.com wrote:
> From: Carsten Haitzler <carsten.haitzler@arm.com>
> 
> KASAN found this problem. find_first_bit() expects to look at a
> pointer pointing to a long, but we look at a u32 - this is going to be
> an issue with endianess but, KSAN already flags this as out-of-bounds
> stack reads. This fixes it by just importing inot a local long.
> 
> Signed-off-by: Carsten Haitzler <carsten.haitzler@arm.com>

Acked-by: Liviu Dudau <liviu.dudau@arm.com>

Best regards,
Liviu

> ---
>  drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c
> index 452e505a1fd3..719a79728e24 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c
> @@ -137,9 +137,10 @@ komeda_pipeline_get_first_component(struct komeda_pipeline *pipe,
>  				    u32 comp_mask)
>  {
>  	struct komeda_component *c = NULL;
> +	unsigned long comp_mask_local = (unsigned long)comp_mask;
>  	int id;
>  
> -	id = find_first_bit((unsigned long *)&comp_mask, 32);
> +	id = find_first_bit(&comp_mask_local, 32);
>  	if (id < 32)
>  		c = komeda_pipeline_get_component(pipe, id);
>  
> -- 
> 2.29.2
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯
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