linux-kernel - Re: [PATCH] kasan: fix slab double free when cpu-hotplug

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Date:   Fri, 4 Dec 2020 20:01:35 +0800
From:   Kuan-Ying Lee <Kuan-Ying.Lee@...iatek.com>
To:     "qiang.zhang@...driver.com" <qiang.zhang@...driver.com>,
        "sfr@...b.auug.org.au" <sfr@...b.auug.org.au>
CC:     "aryabinin@...tuozzo.com" <aryabinin@...tuozzo.com>,
        "dvyukov@...gle.com" <dvyukov@...gle.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "andreyknvl@...gle.com" <andreyknvl@...gle.com>,
        "qcai@...hat.com" <qcai@...hat.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        <walter-zh.wu@...iatek.com>
Subject: Re: [PATCH] kasan: fix slab double free when cpu-hotplug

On Fri, 2020-12-04 at 18:22 +0800, qiang.zhang@...driver.com wrote:
> From: Zqiang <qiang.zhang@...driver.com>
> 
> When a CPU offline, the per-cpu quarantine's offline be set true,
> after this, if the quarantine_put be called in this CPU, the objects
> will be free and return false, free objects doesn't to be done, due
> to return false, the slab memory manager will free this objects.
> 
> Fixes: 41ab1aae781f ("kasan: fix object remaining in offline per-cpu quarantine")
> Signed-off-by: Zqiang <qiang.zhang@...driver.com>
> ---
>  mm/kasan/quarantine.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
> index d98b516f372f..55783125a767 100644
> --- a/mm/kasan/quarantine.c
> +++ b/mm/kasan/quarantine.c
> @@ -194,7 +194,6 @@ bool quarantine_put(struct kmem_cache *cache, void *object)
>  
>  	q = this_cpu_ptr(&cpu_quarantine);
>  	if (q->offline) {
> -		qlink_free(&meta->quarantine_link, cache);
>  		local_irq_restore(flags);
>  		return false;
>  	}

Hi Qiang,

Thanks for fixing this.
Due to that issue, my commit has been removed by Stephen from
linux-next.


Hi Stephen, Andrew,

Should I directly upload the v4 or Stephen can pick the commit which 
has been removed back to the linux-next.

What do you think?

Thanks a lot.

Kuan-Ying