linux-kernel - Re: [PATCH] i2c: tegra: fix a possible NULL dereference

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Message-ID: <20151112122923.GA31671@ulmo>
Date:	Thu, 12 Nov 2015 13:29:23 +0100
From:	Thierry Reding <thierry.reding@...il.com>
To:	LABBE Corentin <clabbe.montjoie@...il.com>
Cc:	gnurou@...il.com, ldewangan@...dia.com, swarren@...dotorg.org,
	wsa@...-dreams.de, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH] i2c: tegra: fix a possible NULL dereference

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

> dereference later at line 809:
> i2c_dev->hw = match->data;
> 
> Signed-off-by: LABBE Corentin <clabbe.montjoie@...il.com>
> ---
>  drivers/i2c/busses/i2c-tegra.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index a0522fc..c803551 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -806,7 +806,10 @@ static int tegra_i2c_probe(struct platform_device *pdev)
>  
>  	if (pdev->dev.of_node) {
>  		const struct of_device_id *match;
> +
>  		match = of_match_device(tegra_i2c_of_match, &pdev->dev);
> +		if (!match)
> +			return -ENODEV;
>  		i2c_dev->hw = match->data;
>  		i2c_dev->is_dvc = of_device_is_compatible(pdev->dev.of_node,
>  						"nvidia,tegra20-i2c-dvc");
> -- 
> 2.4.10
> 

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