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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Fri, 25 Mar 2022 15:57:22 -0400
Message-ID: <CADnq5_NyMsQ_NikyA4r=FULB4MwsjroENZGPgGo-tcAQhhxceQ@mail.gmail.com>
Subject: Re: [PATCH] drm/amd/display: Fix pointer dereferenced before checking
To:     Haowen Bai <baihaowen@meizu.com>
Cc:     "Wentland, Harry" <harry.wentland@amd.com>,
        "Leo (Sunpeng) Li" <sunpeng.li@amd.com>,
        "Siqueira, Rodrigo" <Rodrigo.Siqueira@amd.com>,
        "Deucher, Alexander" <alexander.deucher@amd.com>,
        Christian Koenig <christian.koenig@amd.com>,
        xinhui pan <Xinhui.Pan@amd.com>,
        Dave Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Maling list - DRI developers 
        <dri-devel@lists.freedesktop.org>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>
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Precedence: bulk

Applied both patches.  Thanks!

Alex

On Thu, Mar 24, 2022 at 9:46 AM Haowen Bai <baihaowen@meizu.com> wrote:
>
> 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@meizu.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
>