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From: Cengiz Can <cengiz@kernel.wtf>
To: Dan Carpenter <dan.carpenter@oracle.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "open list:STAGING SUBSYSTEM" <devel@driverdev.osuosl.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: [PATCH] staging: atomisp: move null check to earlier point
Date: Thu, 30 Jul 2020 11:59:10 +0300
Message-ID: <1739ef25b30.2bfa.85c738e3968116fc5c0dc2de74002084@kernel.wtf> (raw)
In-Reply-To: <20200730084545.GB1793@kadam>



On July 30, 2020 11:48:06 Dan Carpenter <dan.carpenter@oracle.com> wrote:

> On Wed, Jul 29, 2020 at 06:13:44PM +0300, Andy Shevchenko wrote:
>> On Wed, Jul 29, 2020 at 5:00 PM Cengiz Can <cengiz@kernel.wtf> wrote:
>>>
>>> `find_gmin_subdev` function that returns a pointer to `struct
>>> gmin_subdev` can return NULL.
>>>
>>> In `gmin_v2p8_ctrl` there's a call to this function but the possibility
>>> of a NULL was not checked before its being dereferenced. ie:
>>>
>>> ```
>>> /* Acquired here --------v */
>>> struct gmin_subdev *gs = find_gmin_subdev(subdev);
>>> int ret;
>>> int value;
>>>
>>> /*  v------Dereferenced here */
>>> if (gs->v2p8_gpio >= 0) {
>>>  pr_info("atomisp_gmin_platform: 2.8v power on GPIO %d\n",
>>>          gs->v2p8_gpio);
>>>  ret = gpio_request(gs->v2p8_gpio, "camera_v2p8");
>>>  if (!ret)
>>>          ret = gpio_direction_output(gs->v2p8_gpio, 0);
>>>  if (ret)
>>>          pr_err("V2P8 GPIO initialization failed\n");
>>> }
>>> ```
>>>
>>> I have moved the NULL check before deref point.
>>
>> "Move the NULL check..."
>> See Submitting Patches documentation how to avoid "This patch", "I", "we", etc.

Noted. Sorry. I'm not a native English speaker.

>>
>
> I always feel like this is a pointless requirement.  We're turning into
> bureaucracts.
>
>>
>>> diff --git a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c 
>>> b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
>>> index 0df46a1af5f0..8e9c5016f299 100644
>>> --- a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
>>> +++ b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
>>> @@ -871,6 +871,11 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev, 
>>> int on)
>>>  int ret;
>>>  int value;
>>>
>>> +       if (!gs) {
>>> +               pr_err("Unable to find gmin subdevice\n");
>>
>>> +               return -EINVAL;
>>
>> And here is a change of semantics...
>
> Yeah.  The change of semantics should be documented in the commit
> message, but it's actually correct.  I discussed this with Mauro earlier
> but my bug reporting script didn't CC a mailing list and I didn't
> catch it.  Mauro suggested:
>
>    53  > Yet, it could make sense to have something like:
>    54  >
>    55  >       if (WARN_ON(!gs))
>    56  >               return -ENODEV;
>    57  >
>    58  > at the beginning of the functions that call find_gmin_subdev().

I will be updating v2 according to this.

>
> regards,
> dan carpenter




  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-29 13:56 Cengiz Can
2020-07-29 15:13 ` Andy Shevchenko
2020-07-30  8:45   ` Dan Carpenter
2020-07-30  8:59     ` Cengiz Can [this message]
2020-07-30 22:17     ` [PATCH v2] " Cengiz Can
2020-07-31  8:38       ` Andy Shevchenko
2020-08-01 21:51         ` [PATCH v3] " Cengiz Can
2020-08-01 21:55         ` [PATCHi v4] " Cengiz Can
2020-08-01 21:58         ` [PATCH v5] " Cengiz Can
2020-08-01 22:01         ` [PATCH v6] " Cengiz Can
2020-08-06 18:34           ` Cengiz Can
2020-08-06 18:39             ` Greg KH
2020-08-06 20:38               ` Cengiz Can
2020-08-06 22:15     ` [PATCH] " Bjorn Helgaas
2020-08-07  9:53       ` Dan Carpenter

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