On 7/21/2024 2:22 PM, Srinivasan Shanmugam wrote:
This commit adds a null check for the set_output_gamma function pointer in the dcn30_set_output_transfer_func function. Previously, set_output_gamma was being checked for nullity at line 386, but then it was being dereferenced without any nullity check at line 401. This could potentially lead to a null pointer dereference error if set_output_gamma is indeed null. To fix this, we now ensure that set_output_gamma is not null before dereferencing it. We do this by adding a nullity check for set_output_gamma before the call to set_output_gamma at line 401. If set_output_gamma is null, we log an error message and do not call the function. This fix prevents a potential null pointer dereference error. drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn30/dcn30_hwseq.c:401 dcn30_set_output_transfer_func() error: we previously assumed 'mpc->funcs->set_output_gamma' could be null (see line 386) drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn30/dcn30_hwseq.c 373 bool dcn30_set_output_transfer_func(struct dc *dc, 374 struct pipe_ctx *pipe_ctx, 375 const struct dc_stream_state *stream) 376 { 377 int mpcc_id = pipe_ctx->plane_res.hubp->inst; 378 struct mpc *mpc = pipe_ctx->stream_res.opp->ctx->dc->res_pool->mpc; 379 const struct pwl_params *params = NULL; 380 bool ret = false; 381 382 /* program OGAM or 3DLUT only for the top pipe*/ 383 if (pipe_ctx->top_pipe == NULL) { 384 /*program rmu shaper and 3dlut in MPC*/ 385 ret = dcn30_set_mpc_shaper_3dlut(pipe_ctx, stream); 386 if (ret == false && mpc->funcs->set_output_gamma) { ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ If this is NULL 387 if (stream->out_transfer_func.type == TF_TYPE_HWPWL) 388 params = &stream->out_transfer_func.pwl; 389 else if (pipe_ctx->stream->out_transfer_func.type == 390 TF_TYPE_DISTRIBUTED_POINTS && 391 cm3_helper_translate_curve_to_hw_format( 392 &stream->out_transfer_func, 393 &mpc->blender_params, false)) 394 params = &mpc->blender_params; 395 /* there are no ROM LUTs in OUTGAM */ 396 if (stream->out_transfer_func.type == TF_TYPE_PREDEFINED) 397 BREAK_TO_DEBUGGER(); 398 } 399 } 400 --> 401 mpc->funcs->set_output_gamma(mpc, mpcc_id, params); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Then it will crash 402 return ret; 403 } Fixes: d99f13878d6f ("drm/amd/display: Add DCN3 HWSEQ") Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: Tom Chung <chiahsuan.chung@xxxxxxx> Cc: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx> Cc: Roman Li <roman.li@xxxxxxx> Cc: Hersen Wu <hersenxs.wu@xxxxxxx> Cc: Alex Hung <alex.hung@xxxxxxx> Cc: Aurabindo Pillai <aurabindo.pillai@xxxxxxx> Cc: Harry Wentland <harry.wentland@xxxxxxx> Cc: Hamza Mahfooz <hamza.mahfooz@xxxxxxx> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@xxxxxxx> --- drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c index eaeeade31ed7..bd807eb79786 100644 --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c @@ -398,7 +398,11 @@ bool dcn30_set_output_transfer_func(struct dc *dc, } }- mpc->funcs->set_output_gamma(mpc, mpcc_id, params);+ if (mpc->funcs->set_output_gamma) + mpc->funcs->set_output_gamma(mpc, mpcc_id, params); + else + DRM_ERROR("set_output_gamma function pointer is NULL.\n");
Maybe we should use DC_LOG_ERROR() instead of DRM_ERROR() in here.
+ return ret; }
