linux-kernel - [PATCH] drm/amd/display: Fix pointer dereferenced before checking

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Date:   Thu, 24 Mar 2022 17:46:02 +0800
From:   Haowen Bai <baihaowen@...zu.com>
To:     <harry.wentland@....com>, <sunpeng.li@....com>,
        <Rodrigo.Siqueira@....com>, <alexander.deucher@....com>,
        <christian.koenig@....com>, <Xinhui.Pan@....com>,
        <airlied@...ux.ie>, <daniel@...ll.ch>
CC:     <amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>, Haowen Bai <baihaowen@...zu.com>
Subject: [PATCH] drm/amd/display: Fix pointer dereferenced before checking

The value actual_pix_clk_100Hz is dereferencing pointer pix_clk_params
before pix_clk_params is being null checked. Fix this by assigning
pix_clk_params->requested_pix_clk_100hz to actual_pix_clk_100Hz only if
pix_clk_params is not NULL, otherwise just NULL.

Signed-off-by: Haowen Bai <baihaowen@...zu.com>
---
 drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
index 2c7eb98..4db45bb 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
@@ -1162,7 +1162,7 @@ static uint32_t dcn3_get_pix_clk_dividers(
 		struct pixel_clk_params *pix_clk_params,
 		struct pll_settings *pll_settings)
 {
-	unsigned long long actual_pix_clk_100Hz = pix_clk_params->requested_pix_clk_100hz;
+	unsigned long long actual_pix_clk_100Hz = pix_clk_params ? pix_clk_params->requested_pix_clk_100hz : 0;
 	struct dce110_clk_src *clk_src;
 
 	clk_src = TO_DCE110_CLK_SRC(cs);
-- 
2.7.4