linux-kernel - [PATCH AUTOSEL 6.6 087/139] drm/amd/display: Add null check for top_pipe_to_program in commit_planes_for

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Message-ID: <20240925121137.1307574-87-sashal@kernel.org>
Date: Wed, 25 Sep 2024 08:08:27 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Srinivasan Shanmugam <srinivasan.shanmugam@....com>,
	Tom Chung <chiahsuan.chung@....com>,
	Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
	Roman Li <roman.li@....com>,
	Alex Hung <alex.hung@....com>,
	Aurabindo Pillai <aurabindo.pillai@....com>,
	Harry Wentland <harry.wentland@....com>,
	Hamza Mahfooz <hamza.mahfooz@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	sunpeng.li@....com,
	christian.koenig@....com,
	Xinhui.Pan@....com,
	airlied@...il.com,
	daniel@...ll.ch,
	alvin.lee2@....com,
	wenjing.liu@....com,
	sungjoon.kim@....com,
	dillon.varone@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.6 087/139] drm/amd/display: Add null check for top_pipe_to_program in commit_planes_for_stream

From: Srinivasan Shanmugam <srinivasan.shanmugam@....com>

[ Upstream commit 66d71a72539e173a9b00ca0b1852cbaa5f5bf1ad ]

This commit addresses a null pointer dereference issue in the
`commit_planes_for_stream` function at line 4140. The issue could occur
when `top_pipe_to_program` is null.

The fix adds a check to ensure `top_pipe_to_program` is not null before
accessing its stream_res. This prevents a null pointer dereference.

Reported by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:4140 commit_planes_for_stream() error: we previously assumed 'top_pipe_to_program' could be null (see line 3906)

Cc: Tom Chung <chiahsuan.chung@....com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@....com>
Cc: Roman Li <roman.li@....com>
Cc: Alex Hung <alex.hung@....com>
Cc: Aurabindo Pillai <aurabindo.pillai@....com>
Cc: Harry Wentland <harry.wentland@....com>
Cc: Hamza Mahfooz <hamza.mahfooz@....com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@....com>
Reviewed-by: Tom Chung <chiahsuan.chung@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 50e643bfdfbad..0b2eb2a6c8e14 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -3797,7 +3797,8 @@ 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);
-- 
2.43.0