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

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Message-ID: <20100930200850.GB4120@redhat.com>
Date:	Thu, 30 Sep 2010 16:08:51 -0400
From:	Dave Jones <davej@...hat.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Davidlohr Bueso <dave@....org>, cpufreq@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH] cpufreq: unnecesary double free in
 pcc_cpufreq_do_osc

On Thu, Sep 30, 2010 at 01:02:54PM -0700, David Rientjes wrote:
  > > index 994230d..db7dc35 100644
 > > --- a/arch/x86/kernel/cpu/cpufreq/pcc-cpufreq.c
 > > +++ 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;
 > 
 > Why is the kfree() unnecessary?  acpi_evaluate_object() will allocate a 
 > new output.pointer if it returns 0, so at this point in the code you would 
 > now be leaking the buffer.
 > 
 > Instead, it would probably be better to fix the existing memory leaks in 
 > that function where we return -ENODEV without going to out_free when 
 > output.length is non-zero.

Oh, *duh*. That was subtle.
You, and Pekka are of course correct.  I'll merge up Pekka's patch.

thanks,

	Dave

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