Received-SPF: pass (google.com: domain of linux-kernel+bounces-59778-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Precedence: bulk
MIME-Version: 1.0
References: <20240206165056.47116-1-n.zhandarovich@fintech.ru>
In-Reply-To: <20240206165056.47116-1-n.zhandarovich@fintech.ru>
From: Alex Deucher <alexdeucher@gmail.com>
Date: Fri, 9 Feb 2024 13:11:06 -0500
Message-ID: <CADnq5_Mj5aj10VyamcXUDuijDPYm9-nmrqR6z1YDhuYmiN7fkg@mail.gmail.com>
Subject: Re: [PATCH] drm/amd/display: fix NULL checks for adev->dm.dc in amdgpu_dm_fini()
To: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Cc: Harry Wentland <harry.wentland@amd.com>, Leo Li <sunpeng.li@amd.com>, 
	Alex Deucher <alexander.deucher@amd.com>, =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>, 
	Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>, "Pan, Xinhui" <Xinhui.Pan@amd.com>, 
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, amd-gfx@lists.freedesktop.org, 
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, 
	lvc-project@linuxtesting.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Applied.  Thanks!

Alex

On Tue, Feb 6, 2024 at 11:51=E2=80=AFAM Nikita Zhandarovich
<n.zhandarovich@fintech.ru> wrote:
>
> Since 'adev->dm.dc' in amdgpu_dm_fini() might turn out to be NULL
> before the call to dc_enable_dmub_notifications(), check
> beforehand to ensure there will not be a possible NULL-ptr-deref
> there.
>
> Also, since commit 1e88eb1b2c25 ("drm/amd/display: Drop
> CONFIG_DRM_AMD_DC_HDCP") there are two separate checks for NULL in
> 'adev->dm.dc' before dc_deinit_callbacks() and dc_dmub_srv_destroy().
> Clean up by combining them all under one 'if'.
>
> Found by Linux Verification Center (linuxtesting.org) with static
> analysis tool SVACE.
>
> Fixes: 81927e2808be ("drm/amd/display: Support for DMUB AUX")
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
> ---
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c    | 16 +++++++---------
>  1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/=
gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index d292f290cd6e..46ac3e6f42bb 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -1938,17 +1938,15 @@ static void amdgpu_dm_fini(struct amdgpu_device *=
adev)
>                 adev->dm.hdcp_workqueue =3D NULL;
>         }
>
> -       if (adev->dm.dc)
> +       if (adev->dm.dc) {
>                 dc_deinit_callbacks(adev->dm.dc);
> -
> -       if (adev->dm.dc)
>                 dc_dmub_srv_destroy(&adev->dm.dc->ctx->dmub_srv);
> -
> -       if (dc_enable_dmub_notifications(adev->dm.dc)) {
> -               kfree(adev->dm.dmub_notify);
> -               adev->dm.dmub_notify =3D NULL;
> -               destroy_workqueue(adev->dm.delayed_hpd_wq);
> -               adev->dm.delayed_hpd_wq =3D NULL;
> +               if (dc_enable_dmub_notifications(adev->dm.dc)) {
> +                       kfree(adev->dm.dmub_notify);
> +                       adev->dm.dmub_notify =3D NULL;
> +                       destroy_workqueue(adev->dm.delayed_hpd_wq);
> +                       adev->dm.delayed_hpd_wq =3D NULL;
> +               }
>         }
>
>         if (adev->dm.dmub_bo)
> --
> 2.25.1
>