RE: linux-4.16-rc5/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c:1723]: (warning) Possible null pointer dereference: pipe_ctx

[Li, Roman]

There is a check just before for-loop that should ensure pipe_ctx is not null:

	/* Only supports single display */
	if (context->stream_count != 1)
		return false;

To remove the subject warning - we can rather add  an assert:
assert(pipe_ctx);

Thanks,
Roman

-----Original Message-----
From: Grodzovsky, Andrey 
Sent: Monday, March 12, 2018 6:23 PM
To: David Binderman <dcb314@xxxxxxxxxxx>; Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Koenig, Christian <Christian.Koenig@xxxxxxx>; Zhou, David(ChunMing) <David1.Zhou@xxxxxxx>; airlied@xxxxxxxx; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Wentland, Harry <Harry.Wentland@xxxxxxx>; Li, Roman <Roman.Li@xxxxxxx>
Subject: Re: linux-4.16-rc5/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c:1723]: (warning) Possible null pointer dereference: pipe_ctx



On 03/12/2018 06:22 AM, David Binderman wrote:
> hello there,
>
> Source code is
>
>
>  ÂÂÂ for (i = 0; i < dc->res_pool->pipe_count; i++) {
>  ÂÂÂÂÂÂÂ if (res_ctx->pipe_ctx[i].stream) {
>  ÂÂÂÂÂÂÂÂÂÂÂ pipe_ctx = &res_ctx->pipe_ctx[i];
>  ÂÂÂÂÂÂÂÂÂÂÂ *pipe_idx = i;
>  ÂÂÂÂÂÂÂÂÂÂÂ break;
>  ÂÂÂÂÂÂÂ }
>  ÂÂÂ }

Indeed something like

if (!pipe_ctx)
 ÂÂÂÂÂÂÂÂÂÂÂÂÂ return false;

seems the right thing here.

Harry, Roman , your opinion ?

Andrey

>
>  ÂÂÂ /* Only supports eDP */
>  ÂÂÂ if (pipe_ctx->stream->sink->link->connector_signal != 
> SIGNAL_TYPE_EDP)
>  ÂÂÂÂÂÂÂ return false;
>
> Suggest add some code to deal with the case that the for loop doesn't 
> find what it is looking for and so pipe_ctx is NULL.
>
> Regards
>
> David Binderman
>      
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