linux-kernel - Re: [PATCH] drm/amd/display: Fix potential null dereference

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Date:   Wed, 5 Apr 2023 14:29:06 -0400
From:   Hamza Mahfooz <hamza.mahfooz@....com>
To:     Igor Artemiev <Igor.A.Artemiev@...t.ru>,
        David Airlie <airlied@...il.com>
Cc:     lvc-project@...uxtesting.org,
        Harry Wentland <harry.wentland@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, Daniel Vetter <daniel@...ll.ch>,
        Alex Deucher <alexander.deucher@....com>,
        Nicholas Kazlauskas <Nicholas.Kazlauskas@....com>
Subject: Re: [PATCH] drm/amd/display: Fix potential null dereference

On 4/3/23 09:10, Igor Artemiev wrote:
> The adev->dm.dc pointer can be NULL and dereferenced in amdgpu_dm_fini()
> without checking.
> 
> Add a NULL pointer check before calling dc_dmub_srv_destroy().
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 9a71c7d31734 ("drm/amd/display: Register DMUB service with DC")
> Signed-off-by: Igor Artemiev <Igor.A.Artemiev@...t.ru>

Applied, thanks!

> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> 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 a01fd41643fc..27f7a554874e 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -1854,7 +1854,8 @@ static void amdgpu_dm_fini(struct amdgpu_device *adev)
>   		dc_deinit_callbacks(adev->dm.dc);
>   #endif
>   
> -	dc_dmub_srv_destroy(&adev->dm.dc->ctx->dmub_srv);
> +	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);
-- 
Hamza