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From: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
To: Emil Velikov <emil.l.velikov@gmail.com>
Cc: "Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Dave Airlie" <airlied@linux.ie>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christian König" <christian.koenig@amd.com>,
	"ML dri-devel" <dri-devel@lists.freedesktop.org>,
	"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
	"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
	linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
	skhan@linuxfoundation.org,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>
Subject: Re: [PATCH v5 3/3] drm: protect drm_master pointers in drm_lease.c
Date: Wed, 30 Jun 2021 14:37:23 +0800	[thread overview]
Message-ID: <e2ca777f-f185-688a-5813-0ff2e5025f77@gmail.com> (raw)
In-Reply-To: <CACvgo514T=PZCWwhNsYqCC504SJ+2WivcRtmHhDoKsWMSLFU4A@mail.gmail.com>

On 30/6/21 8:16 am, Emil Velikov wrote:
> Hi Desmond,
> 
> Couple of small suggestions, with those the series is:
> Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
> 
> On Tue, 29 Jun 2021 at 04:38, Desmond Cheong Zhi Xi
> <desmondcheongzx@gmail.com> wrote:
> 
>> @@ -128,13 +137,20 @@ bool drm_lease_held(struct drm_file *file_priv, int id)
>>          struct drm_master *master;
>>          bool ret;
>>
>> -       if (!file_priv || !file_priv->master || !file_priv->master->lessor)
>> +       if (!file_priv)
>>                  return true;
>>
>> -       master = file_priv->master;
>> +       master = drm_file_get_master(file_priv);
>> +       if (master == NULL)
>> +               return true;
>> +       if (!master->lessor) {
>> +               drm_master_put(&master);
>> +               return true;
> 
> Let's add a "ret = true; goto unlock;" here, so we can have a single
> drm_master_put() in the function.
> Nearly all code paths touched by this patch already follow this approach.
> 
>> @@ -154,10 +170,16 @@ uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs_in)
>>          int count_in, count_out;
>>          uint32_t crtcs_out = 0;
>>
>> -       if (!file_priv || !file_priv->master || !file_priv->master->lessor)
>> +       if (!file_priv)
>>                  return crtcs_in;
>>
>> -       master = file_priv->master;
>> +       master = drm_file_get_master(file_priv);
>> +       if (master == NULL)
>> +               return crtcs_in;
>> +       if (!master->lessor) {
>> +               drm_master_put(&master);
>> +               return crtcs_in;
> 
> Ditto
> 
> Thanks
> Emil
> 

Sounds good to me, I'll revise these functions. Thanks for the review 
and suggestions, Emil.

Best wishes,
Desmond

      reply	other threads:[~2021-06-30  6:37 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-29  3:37 [PATCH v5 0/3] drm: address potential UAF bugs with drm_master ptrs Desmond Cheong Zhi Xi
2021-06-29  3:37 ` [PATCH v5 1/3] drm: avoid circular locks in drm_mode_getconnector Desmond Cheong Zhi Xi
2021-06-29  3:37 ` [PATCH v5 2/3] drm: add a locked version of drm_is_current_master Desmond Cheong Zhi Xi
2021-06-29  3:37 ` [PATCH v5 3/3] drm: protect drm_master pointers in drm_lease.c Desmond Cheong Zhi Xi
2021-06-29 16:07   ` Daniel Vetter
2021-06-30  7:18     ` Desmond Cheong Zhi Xi
2021-06-30  8:02       ` Daniel Vetter
2021-06-30 10:39         ` Desmond Cheong Zhi Xi
2021-06-30  0:16   ` Emil Velikov
2021-06-30  6:37     ` Desmond Cheong Zhi Xi [this message]

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