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From: Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: LABBE Corentin
	<montjoie.mailing-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: LABBE Corentin
	<clabbe.montjoie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	gnurou-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org,
	swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org,
	wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] i2c: tegra: fix a possible NULL dereference
Date: Thu, 12 Nov 2015 14:28:37 +0100	[thread overview]
Message-ID: <20151112132837.GF31671@ulmo> (raw)
In-Reply-To: <20151112125422.GA3758@Red>

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On Thu, Nov 12, 2015 at 01:54:22PM +0100, LABBE Corentin wrote:
> On Thu, Nov 12, 2015 at 01:29:23PM +0100, Thierry Reding wrote:
> > On Thu, Nov 12, 2015 at 08:26:03AM +0100, LABBE Corentin wrote:
> > > of_match_device could return NULL, and so cause a NULL pointer
> > 
> > No. There is no way that of_match_device() can ever fail. The driver
> > core uses the same table to match the OF device to the driver, so the
> > only case where of_match_device() would return NULL is if no match was
> > found, in which case the tegra_i2c_probe() function would never have
> > been called in the first place.
> > 
> > Thierry
> > 
> 
> In a parallel thread for i2c-rcar, the conclusion was different.
> https://lkml.org/lkml/2015/11/12/83

The conclusion was the same: there should be no case where this happens.
The example that Uwe gave is hypothetical and not valid DT in the first
place. So instead of chickening out I think it'd be better to just crash
to make sure people fix the DT.

On a side-note I think that platform_match() should be stricter and do
something like this instead:

	if (dev->of_node) {
		if (of_driver_match_device(dev, drv))
			return 1;

		return 0;
	}

Thierry

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WARNING: multiple messages have this Message-ID
From: Thierry Reding <thierry.reding@gmail.com>
To: LABBE Corentin <montjoie.mailing@gmail.com>
Cc: LABBE Corentin <clabbe.montjoie@gmail.com>,
	gnurou@gmail.com, ldewangan@nvidia.com, swarren@wwwdotorg.org,
	wsa@the-dreams.de, linux-i2c@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org
Subject: Re: [PATCH] i2c: tegra: fix a possible NULL dereference
Date: Thu, 12 Nov 2015 14:28:37 +0100	[thread overview]
Message-ID: <20151112132837.GF31671@ulmo> (raw)
In-Reply-To: <20151112125422.GA3758@Red>

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On Thu, Nov 12, 2015 at 01:54:22PM +0100, LABBE Corentin wrote:
> On Thu, Nov 12, 2015 at 01:29:23PM +0100, Thierry Reding wrote:
> > On Thu, Nov 12, 2015 at 08:26:03AM +0100, LABBE Corentin wrote:
> > > of_match_device could return NULL, and so cause a NULL pointer
> > 
> > No. There is no way that of_match_device() can ever fail. The driver
> > core uses the same table to match the OF device to the driver, so the
> > only case where of_match_device() would return NULL is if no match was
> > found, in which case the tegra_i2c_probe() function would never have
> > been called in the first place.
> > 
> > Thierry
> > 
> 
> In a parallel thread for i2c-rcar, the conclusion was different.
> https://lkml.org/lkml/2015/11/12/83

The conclusion was the same: there should be no case where this happens.
The example that Uwe gave is hypothetical and not valid DT in the first
place. So instead of chickening out I think it'd be better to just crash
to make sure people fix the DT.

On a side-note I think that platform_match() should be stricter and do
something like this instead:

	if (dev->of_node) {
		if (of_driver_match_device(dev, drv))
			return 1;

		return 0;
	}

Thierry

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  reply	other threads:[~2015-11-12 13:28 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-12  7:26 [PATCH] i2c: tegra: fix a possible NULL dereference LABBE Corentin
2015-11-12 12:29 ` Thierry Reding
2015-11-12 12:54   ` LABBE Corentin
2015-11-12 13:28     ` Thierry Reding [this message]
2015-11-12 13:28       ` Thierry Reding
2015-11-12 13:45       ` Uwe Kleine-König
     [not found]         ` <20151112134519.GJ24008-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2015-11-12 13:55           ` Thierry Reding
2015-11-12 13:55             ` Thierry Reding
2015-11-12 14:54             ` LABBE Corentin
2015-11-12 16:14               ` Thierry Reding
2015-11-12 16:14                 ` Thierry Reding
2016-01-23 11:07               ` Wolfram Sang
2016-01-23 11:07                 ` Wolfram Sang
2016-01-23 10:56           ` Wolfram Sang
2016-01-23 10:56             ` Wolfram Sang
2015-11-12 13:40   ` Jon Hunter
2015-11-12 13:40     ` Jon Hunter
2015-11-12 13:55     ` Thierry Reding

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