[PATCH 6.1 474/798] drm/amd/display: Add null check for top_pipe_to_program in commit_planes_for_stream

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Srinivasan Shanmugam <srinivasan.shanmugam@amd.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@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: Alex Hung <alex.hung@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.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 d7bca680805d3..b424465238afc 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -3727,7 +3727,8 @@ 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