linux-kernel - Re: [PATCH] powerpc: fix memory corruption by pnv_alloc_idle_core

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Message-ID: <551BBC49.707@linux.vnet.ibm.com>
Date:	Wed, 01 Apr 2015 15:07:13 +0530
From:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
To:	Jan Stancek <jstancek@...hat.com>, linuxppc-dev@...ts.ozlabs.org,
	mpe@...erman.id.au
CC:	linux-kernel@...r.kernel.org, benh@...nel.crashing.org,
	paulus@...ba.org, mikey@...ling.org, shreyas@...ux.vnet.ibm.com,
	sbest@...hat.com
Subject: Re: [PATCH] powerpc: fix memory corruption by pnv_alloc_idle_core_states

On 03/31/2015 09:41 PM, Jan Stancek wrote:
> Space allocated for paca is based off nr_cpu_ids,
> but pnv_alloc_idle_core_states() iterates paca with
> cpu_nr_cores()*threads_per_core, which is using NR_CPUS.
> 
> This causes pnv_alloc_idle_core_states() to write over memory,
> which is outside of paca array and may later lead to various panics.
> 
> Fixes: 7cba160ad789 (powernv/cpuidle: Redesign idle states management)
> Signed-off-by: Jan Stancek <jstancek@...hat.com>
> ---
>  arch/powerpc/include/asm/cputhreads.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/cputhreads.h b/arch/powerpc/include/asm/cputhreads.h
> index 2bf8e93..4c8ad59 100644
> --- a/arch/powerpc/include/asm/cputhreads.h
> +++ b/arch/powerpc/include/asm/cputhreads.h
> @@ -55,7 +55,7 @@ static inline cpumask_t cpu_thread_mask_to_cores(const struct cpumask *threads)
> 
>  static inline int cpu_nr_cores(void)
>  {
> -	return NR_CPUS >> threads_shift;
> +	return nr_cpu_ids >> threads_shift;
>  }

Thanks for the patch!

Reviewed-by: Preeti U. Murthy <preeti@...ux.vnet.ibm.com>
> 
>  static inline cpumask_t cpu_online_cores_map(void)
> 

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