linux-kernel - Re: [PATCH] drm/i915/gvt/scheduler: fix potential NULL pointer dereference

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Message-ID: <8f70ff7b-9575-006b-2384-88899f24fda6@embeddedor.com>
Date:   Mon, 19 Mar 2018 15:50:12 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Chris Wilson <chris@...is-wilson.co.uk>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Zhi Wang <zhi.a.wang@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>
Cc:     intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/i915/gvt/scheduler: fix potential NULL pointer
 dereference

Hi Chris,

On 03/19/2018 03:38 PM, Chris Wilson wrote:
> Quoting Gustavo A. R. Silva (2018-03-19 19:30:53)
>> _workload_ is being dereferenced before it is null checked, hence
>> there is a potential null pointer dereference.
>>
>> Fix this by moving the pointer dereference after _workload_ has
>> been null checked.
> 
> The checks are misleading and not required.

All of them?

if (!workload || !reg_state || workload->ring_id != RCS)
	return;

or just the null check on workload ?

Thanks for the feedback.
--
Gustavo