linux-kernel - [PATCH AUTOSEL 6.10 149/197] drm/amd/display: Check null-initialized variables

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Message-ID: <20240925115823.1303019-149-sashal@kernel.org>
Date: Wed, 25 Sep 2024 07:52:48 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Alex Hung <alex.hung@....com>,
	Nevenko Stupar <nevenko.stupar@....com>,
	Rodrigo Siqueira <rodrigo.siqueira@....com>,
	Jerry Zuo <jerry.zuo@....com>,
	Daniel Wheeler <daniel.wheeler@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	harry.wentland@....com,
	sunpeng.li@....com,
	Rodrigo.Siqueira@....com,
	christian.koenig@....com,
	Xinhui.Pan@....com,
	airlied@...il.com,
	daniel@...ll.ch,
	alvin.lee2@....com,
	chaitanya.dhere@....com,
	hamza.mahfooz@....com,
	wenjing.liu@....com,
	sohaib.nadeem@....com,
	samson.tam@....com,
	Qingqing.Zhuo@....com,
	dillon.varone@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.10 149/197] drm/amd/display: Check null-initialized variables

From: Alex Hung <alex.hung@....com>

[ Upstream commit 367cd9ceba1933b63bc1d87d967baf6d9fd241d2 ]

[WHAT & HOW]
drr_timing and subvp_pipe are initialized to null and they are not
always assigned new values. It is necessary to check for null before
dereferencing.

This fixes 2 FORWARD_NULL issues reported by Coverity.

Reviewed-by: Nevenko Stupar <nevenko.stupar@....com>
Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@....com>
Signed-off-by: Jerry Zuo <jerry.zuo@....com>
Signed-off-by: Alex Hung <alex.hung@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c
index ebcf5ece209a4..bf8c89fe95a7e 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c
@@ -871,8 +871,9 @@ static bool subvp_drr_schedulable(struct dc *dc, struct dc_state *context)
 	 * for VBLANK: (VACTIVE region of the SubVP pipe can fit the MALL prefetch, VBLANK frame time,
 	 * and the max of (VBLANK blanking time, MALL region)).
 	 */
-	if (stretched_drr_us < (1 / (double)drr_timing->min_refresh_in_uhz) * 1000000 * 1000000 &&
-			subvp_active_us - prefetch_us - stretched_drr_us - max_vblank_mallregion > 0)
+	if (drr_timing &&
+	    stretched_drr_us < (1 / (double)drr_timing->min_refresh_in_uhz) * 1000000 * 1000000 &&
+	    subvp_active_us - prefetch_us - stretched_drr_us - max_vblank_mallregion > 0)
 		schedulable = true;
 
 	return schedulable;
@@ -937,7 +938,7 @@ static bool subvp_vblank_schedulable(struct dc *dc, struct dc_state *context)
 		if (!subvp_pipe && pipe_mall_type == SUBVP_MAIN)
 			subvp_pipe = pipe;
 	}
-	if (found) {
+	if (found && subvp_pipe) {
 		phantom_stream = dc_state_get_paired_subvp_stream(context, subvp_pipe->stream);
 		main_timing = &subvp_pipe->stream->timing;
 		phantom_timing = &phantom_stream->timing;
-- 
2.43.0