linux-kernel - [lvc-project] [PATCH] drm/amd/display: Fix potential null dereference

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Date:   Fri, 29 Sep 2023 18:33:45 +0300
From:   Igor Artemiev <Igor.A.Artemiev@...t.ru>
To:     Harry Wentland <harry.wentland@....com>
Cc:     Igor Artemiev <Igor.A.Artemiev@...t.ru>,
        Leo Li <sunpeng.li@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        lvc-project@...uxtesting.org
Subject: [lvc-project] [PATCH] drm/amd/display: Fix potential null dereference

The 'top_pipe_to_program pointer' can be NULL and it is checked 
at the first dereference, but not at the second. 

Add a check before using it.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Igor Artemiev <Igor.A.Artemiev@...t.ru>
---
 drivers/gpu/drm/amd/display/dc/core/dc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 3a9077b60029..154ad23ff931 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -3824,7 +3824,8 @@ static void commit_planes_for_stream(struct dc *dc,
 	}
 
 	if ((update_type != UPDATE_TYPE_FAST) && stream->update_flags.bits.dsc_changed)
-		if (top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
+		if (top_pipe_to_program &&
+				top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
 			top_pipe_to_program->stream_res.tg->funcs->wait_for_state(
 				top_pipe_to_program->stream_res.tg,
 				CRTC_STATE_VACTIVE);
-- 
2.30.2