Re: [PATCH] drm/amd/display: fix the system memory page fault because of copy overflow

[Lee Jones <lee.jones@linaro.org>]

On Sat, 16 Jan 2021, Huang Rui wrote:

> The buffer is allocated with the size of pointer and copy with the size of
> data structure. Then trigger the system memory page fault. Use the
> orignal data structure to get the object size.
> 
> Fixes: a8e30005b drm/amd/display/dc/core/dc_link: Move some local data
> from the stack to the heap
> 
> Signed-off-by: Huang Rui <ray.huang@amd.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> ---
>  drivers/gpu/drm/amd/display/dc/core/dc_link.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> index 69573d67056d..73178978ae74 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> @@ -1380,7 +1380,7 @@ static bool dc_link_construct(struct dc_link *link,
>  
>  	DC_LOGGER_INIT(dc_ctx->logger);
>  
> -	info = kzalloc(sizeof(info), GFP_KERNEL);

Ah sorry, this should be (*info).

> +	info = kzalloc(sizeof(struct integrated_info), GFP_KERNEL);

Using the full name like this is usually discouraged.

>  	if (!info)
>  		goto create_fail;
>  
> @@ -1545,7 +1545,7 @@ static bool dc_link_construct(struct dc_link *link,
>  	}
>  
>  	if (bios->integrated_info)
> -		memcpy(info, bios->integrated_info, sizeof(*info));

This should be correct.

> +		memcpy(info, bios->integrated_info, sizeof(struct integrated_info));
>  
>  	/* Look for channel mapping corresponding to connector and device tag */
>  	for (i = 0; i < MAX_NUMBER_OF_EXT_DISPLAY_PATH; i++) {

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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