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

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>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index b8a6c062426d9c77cbf102fb8f83f6a06bbd338a..95d6e29d5e472a8ab517bf0709931dbbc64ef318 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -4137,7 +4137,8 @@ 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);