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Subject: Re: [RESEND PATCH] cpufreq: unnecesary double free in
 pcc_cpufreq_do_osc
From: Davidlohr Bueso <dave@gnu.org>
Reply-To: dave@gnu.org
To: Dave Jones <davej@redhat.com>
Cc: David Rientjes <rientjes@google.com>, cpufreq@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
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Date: Thu, 30 Sep 2010 16:17:31 -0400
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On Thu, 2010-09-30 at 16:08 -0400, Dave Jones wrote:
> 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.

Yep, anyways, at least we got the correct "fix".

> You, and Pekka are of course correct.  I'll merge up Pekka's patch.
> 
> thanks,
> 
> 	Dave
> 
>