linux-kernel - Re: [PATCH] pwm: sun4i: fix a possible NULL dereference

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Message-ID: <20151112123828.GB31671@ulmo>
Date:	Thu, 12 Nov 2015 13:38:28 +0100
From:	Thierry Reding <thierry.reding@...il.com>
To:	LABBE Corentin <clabbe.montjoie@...il.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	maxime.ripard@...e-electrons.com, wens@...e.org,
	linux-kernel@...r.kernel.org, linux-pwm@...r.kernel.org
Subject: Re: [PATCH] pwm: sun4i: fix a possible NULL dereference

On Thu, Nov 12, 2015 at 08:42:12AM +0100, LABBE Corentin wrote:
> of_match_device could return NULL, and so cause a NULL pointer
> dereference later.
> 
> Reported-by: coverity (CID 1324139)
> Signed-off-by: LABBE Corentin <clabbe.montjoie@...il.com>
> ---
>  drivers/pwm/pwm-sun4i.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index cd9dde5..3011fcc 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -291,6 +291,8 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>  	const struct of_device_id *match;
>  
>  	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
> +	if (!match)
> +		return -ENODEV;

I explained this in a reply to another similar patch, but that was a
different audience, so here goes again: the driver core will use the
same device ID table to match on the driver, so the case where NULL
would be returned is the same case in which sun4i_pwm_probe() would
never have been called in the first place.

Thierry

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