drm/amd/display: Add null check for top_pipe_to_program in commit_planes_for_stream

[ 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>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 272252cd0500151da052ec872bf987074333acfd..05875980092334eaa538987793554d020350fb1b 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -2614,7 +2614,8 @@ static void commit_planes_for_stream(struct dc *dc,
                dc->hwss.pipe_control_lock(dc, top_pipe_to_program, false);
 
        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);