Patch "drm/amd/display: Check link_res->hpo_dp_link_enc before using it" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/amd/display: Check link_res->hpo_dp_link_enc before using it

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amd-display-check-link_res-hpo_dp_link_enc-befor.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7f9dfc71e72f01f2d53185ddec3909bec9c71aed
Author: Alex Hung <alex.hung@xxxxxxx>
Date:   Thu Jun 27 16:45:39 2024 -0600

    drm/amd/display: Check link_res->hpo_dp_link_enc before using it
    
    [ Upstream commit 0beca868cde8742240cd0038141c30482d2b7eb8 ]
    
    [WHAT & HOW]
    Functions dp_enable_link_phy and dp_disable_link_phy can pass link_res
    without initializing hpo_dp_link_enc and it is necessary to check for
    null before dereferencing.
    
    This fixes 2 FORWARD_NULL issues reported by Coverity.
    
    Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@xxxxxxx>
    Signed-off-by: Jerry Zuo <jerry.zuo@xxxxxxx>
    Signed-off-by: Alex Hung <alex.hung@xxxxxxx>
    Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/amd/display/dc/link/hwss/link_hwss_hpo_dp.c b/drivers/gpu/drm/amd/display/dc/link/hwss/link_hwss_hpo_dp.c
index e1257404357b1..d0148f10dfc0a 100644
--- a/drivers/gpu/drm/amd/display/dc/link/hwss/link_hwss_hpo_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/link/hwss/link_hwss_hpo_dp.c
@@ -28,6 +28,8 @@
 #include "dccg.h"
 #include "clk_mgr.h"
 
+#define DC_LOGGER link->ctx->logger
+
 void set_hpo_dp_throttled_vcp_size(struct pipe_ctx *pipe_ctx,
 		struct fixed31_32 throttled_vcp_size)
 {
@@ -124,6 +126,11 @@ void disable_hpo_dp_link_output(struct dc_link *link,
 		const struct link_resource *link_res,
 		enum signal_type signal)
 {
+	if (!link_res->hpo_dp_link_enc) {
+		DC_LOG_ERROR("%s: invalid hpo_dp_link_enc\n", __func__);
+		return;
+	}
+
 		link_res->hpo_dp_link_enc->funcs->link_disable(link_res->hpo_dp_link_enc);
 		link_res->hpo_dp_link_enc->funcs->disable_link_phy(
 				link_res->hpo_dp_link_enc, signal);