linux-kernel - Re: [PATCH] mm: kfence: fix using kfence_metadata without initialization in show

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Date:   Wed, 15 Mar 2023 12:54:25 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Marco Elver <elver@...gle.com>
Cc:     Muchun Song <songmuchun@...edance.com>, glider@...gle.com,
        dvyukov@...gle.com, jannh@...gle.com, sjpark@...zon.de,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, muchun.song@...ux.dev
Subject: Re: [PATCH] mm: kfence: fix using kfence_metadata without
 initialization in show_object()

On Wed, 15 Mar 2023 09:07:40 +0100 Marco Elver <elver@...gle.com> wrote:

> On Wed, 15 Mar 2023 at 04:45, Muchun Song <songmuchun@...edance.com> wrote:
> >
> > The variable kfence_metadata is initialized in kfence_init_pool(), then, it is
> > not initialized if kfence is disabled after booting. In this case, kfence_metadata
> > will be used (e.g. ->lock and ->state fields) without initialization when reading
> > /sys/kernel/debug/kfence/objects. There will be a warning if you enable
> > CONFIG_DEBUG_SPINLOCK. Fix it by creating debugfs files when necessary.
> >
> > Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
> > Signed-off-by: Muchun Song <songmuchun@...edance.com>
> 
> Tested-by: Marco Elver <elver@...gle.com>
> Reviewed-by: Marco Elver <elver@...gle.com>

Thanks, I'll add cc:stable to this.

I assume the warning is the only known adverse effect of this bug?