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

[Christian König]

Am 15.01.21 um 19:46 schrieb Huang Rui:
> 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 at amd.com>
> Cc: Lee Jones <lee.jones at 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);
> +	info = kzalloc(sizeof(struct integrated_info), GFP_KERNEL);

That should probably be sizeof(*info) instead, we usually try to avoid 
sizeof(struct ...) in the kernel.

There are some automated scripts in place which will send you a patch to 
change it otherwise.

>   	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));
> +		memcpy(info, bios->integrated_info, sizeof(struct integrated_info));

This can then also stay as it is.

Apart from that good catch.

Regards,
Christian.

>   
>   	/* Look for channel mapping corresponding to connector and device tag */
>   	for (i = 0; i < MAX_NUMBER_OF_EXT_DISPLAY_PATH; i++) {