linux-kernel - Re: [RESEND PATCH] cpufreq: unnecesary double free in pcc_cpufreq_do

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Message-ID: <20100930200617.GA4120@redhat.com>
Date:	Thu, 30 Sep 2010 16:06:17 -0400
From:	Dave Jones <davej@...hat.com>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	dave@....org, cpufreq@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	x86 maintainers <x86@...nel.org>
Subject: Re: [RESEND PATCH] cpufreq: unnecesary double free in
 pcc_cpufreq_do_osc

On Thu, Sep 30, 2010 at 10:59:51PM +0300, Pekka Enberg wrote:
 > > +++ b/arch/x86/kernel/cpu/cpufreq/pcc-cpufreq.c
 > > @@ -379,6 +379,8 @@ static int __init pcc_cpufreq_do_osc(acpi_handle *handle)
 > >        if (!(supported & 0x1))
 > >                return -ENODEV;
 > >
 > > +       return ret;
 > > +
 > >  out_free:
 > >        kfree(output.pointer);
 > >        return ret;
 > 
 > Where is the double free here? I can't see it. I do see memory leaks
 > happening in error handling paths of pcc_cpufreq_do_osc() which makes
 > me think we need something like the attached patch.

I think Dave's patch is correct.  There's a kfree(output.pointer) at line 359.
If we fall all the way through without hitting any of the return -ENODEVs,
we end up doing a 2nd kfree in the out_free:

	Dave

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