Re: [RESEND PATCH] cpufreq: unnecesary double free inpcc_cpufreq_do_osc

From: Dave Jones
Date: Thu Sep 30 2010 - 16:06:49 EST


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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