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 <[email protected]>
Cc: Tom Chung <[email protected]>
Cc: Rodrigo Siqueira <[email protected]>
Cc: Roman Li <[email protected]>
Cc: Hersen Wu <[email protected]>
Cc: Alex Hung <[email protected]>
Cc: Aurabindo Pillai <[email protected]>
Cc: Harry Wentland <[email protected]>
Cc: Hamza Mahfooz <[email protected]>
Signed-off-by: Srinivasan Shanmugam <[email protected]>
---
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;
}
