linux-kernel - Re: [PATCH] x86/resctrl: Fix potential memory leak

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Message-ID: <1da649da-6527-d4c2-7d12-40126856ae75@intel.com>
Date:   Thu, 19 Dec 2019 15:26:29 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Shakeel Butt <shakeelb@...gle.com>,
        Fenghua Yu <fenghua.yu@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/resctrl: Fix potential memory leak

Hi Shakeel,

On 12/19/2019 2:38 PM, Shakeel Butt wrote:
> The set_cache_qos_cfg() is leaking memory when the given level is not
> RDT_RESOURCE_L3 or RDT_RESOURCE_L2. Fix that.

I think it would be valuable to those considering whether they need to
backport to know that RDT_RESOURCE_L3 and RDT_RESOURCE_L2 are currently
the only possible levels with which this function is called. It is thus
not currently possible for this leak to occur. Indeed a valuable safety
to add in case this code may change in the future. Thank you very much.

> 
> Fixes: 99adde9b370de ("x86/intel_rdt: Enable L2 CDP in MSR IA32_L2_QOS_CFG")
> Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
> ---
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 2e3b06d6bbc6..a0c279c7f4b9 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1748,8 +1748,10 @@ static int set_cache_qos_cfg(int level, bool enable)
>  		update = l3_qos_cfg_update;
>  	else if (level == RDT_RESOURCE_L2)
>  		update = l2_qos_cfg_update;
> -	else
> +	else {
> +		free_cpumask_var(cpu_mask);
>  		return -EINVAL;
> +	}
>  
>  	r_l = &rdt_resources_all[level];
>  	list_for_each_entry(d, &r_l->domains, list) {
> 

Reinette