[PATCH 1/3] drm/amd/display: Add NULL check for function pointer in dcn20_set_output_transfer_func

[Chung, ChiaHsuan (Tom)]

Reviewed-by: Tom Chung <chiahsuan.chung at amd.com>

On 7/31/2024 3:57 PM, Srinivasan Shanmugam wrote:
> This commit adds a null check for the set_output_gamma function pointer
> in the dcn20_set_output_transfer_func function. Previously,
> set_output_gamma was being checked for null at line 1030, but then it
> was being dereferenced without any null check at line 1048. This could
> potentially lead to a null pointer dereference error if set_output_gamma
> is null.
>
> To fix this, we now ensure that set_output_gamma is not null before
> dereferencing it. We do this by adding a null check for set_output_gamma
> before the call to set_output_gamma at line 1048.
>
> Cc: Tom Chung <chiahsuan.chung at amd.com>
> Cc: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
> Cc: Roman Li <roman.li at amd.com>
> Cc: Alex Hung <alex.hung at amd.com>
> Cc: Aurabindo Pillai <aurabindo.pillai at amd.com>
> Cc: Harry Wentland <harry.wentland at amd.com>
> Cc: Hamza Mahfooz <hamza.mahfooz at amd.com>
> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
> ---
>   drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
> index 5a6064999033..425432ca497f 100644
> --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
> @@ -1045,7 +1045,8 @@ bool dcn20_set_output_transfer_func(struct dc *dc, struct pipe_ctx *pipe_ctx,
>   	/*
>   	 * if above if is not executed then 'params' equal to 0 and set in bypass
>   	 */
> -	mpc->funcs->set_output_gamma(mpc, mpcc_id, params);
> +	if (mpc->funcs->set_output_gamma)
> +		mpc->funcs->set_output_gamma(mpc, mpcc_id, params);
>   
>   	return true;
>   }