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Message-ID: <20130114173826.GA917@gmail.com>
Date: Mon, 14 Jan 2013 17:38:26 +0000
From: Cong Ding <dinggnu@...il.com>
To: Russell King - ARM Linux <linux@....linux.org.uk>
Cc: Will Deacon <will.deacon@....com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Paul Mackerras <paulus@...ba.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm: kernel/perf_event_cpu.c: fix error null pointer
dereference check
On Mon, Jan 14, 2013 at 05:23:46PM +0000, Russell King - ARM Linux wrote:
> On Mon, Jan 14, 2013 at 05:18:53PM +0000, Cong Ding wrote:
> > the pointer cpu_pmu is used without null pointer dereference check, and is
> > checked after the using of it, so we move the null pointer check to before the
> > first use.
>
> The NULL pointer check is not necessary. cpu_pmu_init() is called
> after cpu_pmu has already been dereferenced by its caller:
>
> cpu_pmu = pmu;
> cpu_pmu->plat_device = pdev;
> cpu_pmu_init(cpu_pmu);
>
> So...
>
> > - /* Ensure the PMU has sane values out of reset. */
> > - if (cpu_pmu && cpu_pmu->reset)
>
> Just replace this with:
> if (cpu_pmu->reset)
Thanks Russell, I will send version 2.
- cong
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