From f7ea1305437ccf4a5ef9d008d4df709b35a955c7 Mon Sep 17 00:00:00 2001
From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Date: Fri, 17 Dec 2021 14:18:59 -0500
Subject: drm/amd/display: Fix USB4 null pointer dereference in
update_psp_stream_config
Git-commit: 33bb63915fee190102cae7d6576bc51a0bc342b2
Patch-mainline: v5.16-rc8
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
Alt-commit: 88eabcb8e6965b38331618f60567dfe92ad3c42c
[Why]
A porting error on a previous patch left the block of code that
causes the crash from a NULL pointer dereference.
More specifically, we try to access link_enc before it's assigned in
the USB4 case in the following assignment:
config.dio_output_idx = link_enc->transmitter - TRANSMITTER_UNIPHY_A;
[How]
That assignment occurs later depending on the ASIC version. It's only
needed on DCN31 and only after link_enc is already assigned.
Fixes: 986430446c917b ("drm/amd/display: fix a crash on USB4 over C20 PHY")
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/amd/display/dc/core/dc_link.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index c8457babfdea..c0bdc23702c8 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -3945,12 +3945,9 @@ static void update_psp_stream_config(struct pipe_ctx *pipe_ctx, bool dpms_off)
config.dig_be = pipe_ctx->stream->link->link_enc_hw_inst;
#if defined(CONFIG_DRM_AMD_DC_DCN)
config.stream_enc_idx = pipe_ctx->stream_res.stream_enc->id - ENGINE_ID_DIGA;
-
+
if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_PHY ||
pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA) {
- link_enc = pipe_ctx->stream->link->link_enc;
- config.dio_output_type = pipe_ctx->stream->link->ep_type;
- config.dio_output_idx = link_enc->transmitter - TRANSMITTER_UNIPHY_A;
if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_PHY)
link_enc = pipe_ctx->stream->link->link_enc;
else if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA)
--
2.38.1