linux-kernel - Re: [PATCH] PM / OPP: Initialize regulator pointer to an error value

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <17646703.2nZXD4icYj@wuerfel>
Date:	Mon, 15 Feb 2016 21:38:14 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	linaro-kernel@...ts.linaro.org
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	Rafael Wysocki <rjw@...ysocki.net>,
	Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Jon Hunter <jonathanh@...dia.com>,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH] PM / OPP: Initialize regulator pointer to an error value

On Monday 15 February 2016 21:56:42 Viresh Kumar wrote:
> We are currently required to do two checks for regulator pointer:
> IS_ERR() and IS_NULL().
> 
> And multiple instances are reported, about both of these not being used
> consistently and so resulting in crashes.
> 
> Fix that by initializing regulator pointer with an error value and
> checking it only against an error.
> 
> This makes code consistent and efficient.

There is usually something else wrong if you have to check for both.
Why exactly do you need to check for both IS_ERR and NULL?

> diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
> index d7cd4e265766..146b6197d598 100644
> --- a/drivers/base/power/opp/core.c
> +++ b/drivers/base/power/opp/core.c
> @@ -257,7 +257,7 @@ unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev)
>  	}
>  
>  	reg = dev_opp->regulator;
> -	if (IS_ERR_OR_NULL(reg)) {
> +	if (IS_ERR(reg)) {
>  		/* Regulator may not be required for device */
>  		if (reg)
>  			dev_err(dev, "%s: Invalid regulator (%ld)\n", __func__,
> @@ -798,6 +798,9 @@ static struct device_opp *_add_device_opp(struct device *dev)
>  		of_node_put(np);
>  	}
>  
> +	/* Set regulator to a non-NULL error value */
> +	dev_opp->regulator = ERR_PTR(-EFAULT);
> +
>  	/* Find clk for the device */
>  	dev_opp->clk = clk_get(dev, NULL);
>  	if (IS_ERR(dev_opp->clk)) {

-EFAULT has a very specific meaning (accessing an invalid pointer from
user space), I don't think you want that one.

	Arnd