Re: [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

From: Greg KH
Date: Thu Dec 12 2024 - 07:11:36 EST


On Wed, Dec 11, 2024 at 06:15:44PM +0800, jianqi.ren.cn@xxxxxxxxxxxxx wrote:
> From: Wayne Lin <wayne.lin@xxxxxxx>
>
> [ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]
>
> [Why]
> When unplug one of monitors connected after mst hub, encounter null pointer dereference.
>
> It's due to dc_sink get released immediately in early_unregister() or detect_ctx(). When
> commit new state which directly referring to info stored in dc_sink will cause null pointer
> dereference.
>
> [how]
> Remove redundant checking condition. Relevant condition should already be covered by checking
> if dsc_aux is null or not. Also reset dsc_aux to NULL when the connector is disconnected.
>
> Reviewed-by: Jerry Zuo <jerry.zuo@xxxxxxx>
> Acked-by: Zaeem Mohamed <zaeem.mohamed@xxxxxxx>
> Signed-off-by: Wayne Lin <wayne.lin@xxxxxxx>
> Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
> Signed-off-by: Jianqi Ren <jianqi.ren.cn@xxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 4 ++++
> 1 file changed, 4 insertions(+)

You sent this 3 times, all different, so I have no idea what to do.

Ok, I give up. I'm deleting ALL of your pending stable patches from my
review queue now due to all of the problems that these have had.

Please work with a more experienced kernel developer at your company to
get these backports correct, and complete, and send them as a patch
series with the correct information and documentation as to what is
going on, so that we have a chance to get this right.

thanks,

greg k-h