linux-kernel - [PATCH 1/2] drm/amd/display: Fix null check for pipe_ctx->plane_state in dcn20_program

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Message-ID: <20241105140137.2465572-2-quzicheng@huawei.com>
Date: Tue, 5 Nov 2024 14:01:36 +0000
From: Zicheng Qu <quzicheng@...wei.com>
To: <harry.wentland@....com>, <sunpeng.li@....com>,
	<Rodrigo.Siqueira@....com>, <alexander.deucher@....com>,
	<christian.koenig@....com>, <Xinhui.Pan@....com>, <airlied@...il.com>,
	<simona@...ll.ch>, <Dillon.Varone@....com>, <Alvin.Lee2@....com>,
	<nicholas.kazlauskas@....com>, <alex.hung@....com>,
	<aurabindo.pillai@....com>, <relja.vojvodic@....com>,
	<chiahsuan.chung@....com>, <wenjing.liu@....com>, <george.shen@....com>,
	<mwen@...lia.com>, <yi-lchen@....com>, <martin.leung@....com>,
	<srinivasan.shanmugam@....com>, <stylon.wang@....com>, <jun.lei@....com>,
	<amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>
CC: <tanghui20@...wei.com>, <zhangqiao22@...wei.com>,
	<judy.chenhui@...wei.com>, <quzicheng@...wei.com>
Subject: [PATCH 1/2] drm/amd/display: Fix null check for pipe_ctx->plane_state in dcn20_program_pipe

This commit addresses a null pointer dereference issue in
dcn20_program_pipe(). Previously, commit 8e4ed3cf1642 ("drm/amd/display:
Add null check for pipe_ctx->plane_state in dcn20_program_pipe")
partially fixed the null pointer dereference issue. However, in
dcn20_update_dchubp_dpp(), the variable pipe_ctx is passed in, and
plane_state is accessed again through pipe_ctx. Multiple if statements
directly call attributes of plane_state, leading to potential null
pointer dereference issues. This patch adds necessary null checks to
ensure stability.

Fixes: 8e4ed3cf1642 ("drm/amd/display: Add null check for pipe_ctx->plane_state in dcn20_program_pipe")
Signed-off-by: Zicheng Qu <quzicheng@...wei.com>
---
 drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
index a80c08582932..36d12db8d022 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
@@ -1923,9 +1923,9 @@ static void dcn20_program_pipe(
 				dc->res_pool->hubbub, pipe_ctx->plane_res.hubp->inst, pipe_ctx->hubp_regs.det_size);
 	}
 
-	if (pipe_ctx->update_flags.raw ||
-	    (pipe_ctx->plane_state && pipe_ctx->plane_state->update_flags.raw) ||
-	    pipe_ctx->stream->update_flags.raw)
+	if (pipe_ctx->plane_state && (pipe_ctx->update_flags.raw ||
+	    pipe_ctx->plane_state->update_flags.raw ||
+	    pipe_ctx->stream->update_flags.raw))
 		dcn20_update_dchubp_dpp(dc, pipe_ctx, context);
 
 	if (pipe_ctx->plane_state && (pipe_ctx->update_flags.bits.enable ||
-- 
2.34.1