drm/amd/display: Add null check for pipe_ctx->plane_state in dcn20_program_pipe

This commit addresses a null pointer dereference issue in the
`dcn20_program_pipe` function. The issue could occur when
`pipe_ctx->plane_state` is null.

The fix adds a check to ensure `pipe_ctx->plane_state` is not null
before accessing. This prevents a null pointer dereference.

Reported by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn20/dcn20_hwseq.c:1925 dcn20_program_pipe() error: we previously assumed 'pipe_ctx->plane_state' could be null (see line 1877)

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/hwss/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
index 270e337ae27bbcb5f6bf396cbd84c6a48f433851..5a6064999033b2ff7eb19fa13686113be485e445 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
@@ -1922,22 +1922,29 @@ static void dcn20_program_pipe(
                                dc->res_pool->hubbub, pipe_ctx->plane_res.hubp->inst, pipe_ctx->hubp_regs.det_size);
        }
 
-       if (pipe_ctx->update_flags.raw || pipe_ctx->plane_state->update_flags.raw || pipe_ctx->stream->update_flags.raw)
+       if (pipe_ctx->update_flags.raw ||
+           (pipe_ctx->plane_state && pipe_ctx->plane_state->update_flags.raw) ||
+           pipe_ctx->stream->update_flags.raw)
                dcn20_update_dchubp_dpp(dc, pipe_ctx, context);
 
-       if (pipe_ctx->update_flags.bits.enable
-                       || pipe_ctx->plane_state->update_flags.bits.hdr_mult)
+       if (pipe_ctx->update_flags.bits.enable ||
+           (pipe_ctx->plane_state && pipe_ctx->plane_state->update_flags.bits.hdr_mult))
                hws->funcs.set_hdr_multiplier(pipe_ctx);
 
        if (hws->funcs.populate_mcm_luts) {
-               hws->funcs.populate_mcm_luts(dc, pipe_ctx, pipe_ctx->plane_state->mcm_luts,
-                               pipe_ctx->plane_state->lut_bank_a);
-               pipe_ctx->plane_state->lut_bank_a = !pipe_ctx->plane_state->lut_bank_a;
+               if (pipe_ctx->plane_state) {
+                       hws->funcs.populate_mcm_luts(dc, pipe_ctx, pipe_ctx->plane_state->mcm_luts,
+                                                    pipe_ctx->plane_state->lut_bank_a);
+                       pipe_ctx->plane_state->lut_bank_a = !pipe_ctx->plane_state->lut_bank_a;
+               }
        }
        if (pipe_ctx->update_flags.bits.enable ||
-           pipe_ctx->plane_state->update_flags.bits.in_transfer_func_change ||
-           pipe_ctx->plane_state->update_flags.bits.gamma_change ||
-           pipe_ctx->plane_state->update_flags.bits.lut_3d)
+           (pipe_ctx->plane_state &&
+            pipe_ctx->plane_state->update_flags.bits.in_transfer_func_change) ||
+           (pipe_ctx->plane_state &&
+            pipe_ctx->plane_state->update_flags.bits.gamma_change) ||
+           (pipe_ctx->plane_state &&
+            pipe_ctx->plane_state->update_flags.bits.lut_3d))
                hws->funcs.set_input_transfer_func(dc, pipe_ctx, pipe_ctx->plane_state);
 
        /* dcn10_translate_regamma_to_hw_format takes 750us to finish
@@ -1947,7 +1954,8 @@ static void dcn20_program_pipe(
        if (pipe_ctx->update_flags.bits.enable ||
                        pipe_ctx->update_flags.bits.plane_changed ||
                        pipe_ctx->stream->update_flags.bits.out_tf ||
-                       pipe_ctx->plane_state->update_flags.bits.output_tf_change)
+                       (pipe_ctx->plane_state &&
+                        pipe_ctx->plane_state->update_flags.bits.output_tf_change))
                hws->funcs.set_output_transfer_func(dc, pipe_ctx, pipe_ctx->stream);
 
        /* If the pipe has been enabled or has a different opp, we
@@ -1971,7 +1979,7 @@ static void dcn20_program_pipe(
        }
 
        /* Set ABM pipe after other pipe configurations done */
-       if (pipe_ctx->plane_state->visible) {
+       if ((pipe_ctx->plane_state && pipe_ctx->plane_state->visible)) {
                if (pipe_ctx->stream_res.abm) {
                        dc->hwss.set_pipe(pipe_ctx);
                        pipe_ctx->stream_res.abm->funcs->set_abm_level(pipe_ctx->stream_res.abm,