linux-kernel - Re: [PATCH mm] fix for "kasan, fork: reset pointer tags of vmapped stacks"

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Date:   Wed, 16 Feb 2022 16:20:49 +0100
From:   Andrey Konovalov <andreyknvl@...il.com>
To:     Marco Elver <elver@...gle.com>
Cc:     andrey.konovalov@...ux.dev,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: Re: [PATCH mm] fix for "kasan, fork: reset pointer tags of vmapped stacks"

On Wed, Feb 16, 2022 at 10:59 AM Marco Elver <elver@...gle.com> wrote:
>
> On Tue, 15 Feb 2022 at 17:52, <andrey.konovalov@...ux.dev> wrote:
> >
> > From: Andrey Konovalov <andreyknvl@...gle.com>
> >
> > That patch didn't update the case when a stack is retrived from
> > cached_stacks in alloc_thread_stack_node(). As cached_stacks stores
> > vm_structs and not stack pointers themselves, the pointer tag needs
> > to be reset there as well.
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
>
> Reviewed-by: Marco Elver <elver@...gle.com>
>
> Did the test catch this? If not, can this be tested?

Kind of, the kernel crashes on boot. I got KASAN_STACK accidentally
disabled in my SW_TAGS config, so I didn't see the crash until now.