From: Qian Cai <cai@lca.pw>
To: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Kees Cook <keescook@chromium.org>,
kasan-dev <kasan-dev@googlegroups.com>,
Linux-MM <linux-mm@kvack.org>,
linux-s390 <linux-s390@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>
Subject: Re: [PATCH] mm/page_alloc: silence a KASAN false positive
Date: Wed, 10 Jun 2020 08:28:17 -0400 [thread overview]
Message-ID: <20200610122817.GC954@lca.pw> (raw)
In-Reply-To: <CAG_fn=X-da3V0OC-Bzd2rmkNuZ_bVpH_n7Sp5P_hSGXD4ryyBA@mail.gmail.com>
On Wed, Jun 10, 2020 at 01:02:04PM +0200, Alexander Potapenko wrote:
> On Wed, Jun 10, 2020 at 7:55 AM Dmitry Vyukov <dvyukov@google.com> wrote:
> >
> > On Wed, Jun 10, 2020 at 7:22 AM Qian Cai <cai@lca.pw> wrote:
> > >
> > > kernel_init_free_pages() will use memset() on s390 to clear all pages
> > > from kmalloc_order() which will override KASAN redzones because a
> > > redzone was setup from the end of the allocation size to the end of the
> > > last page. Silence it by not reporting it there. An example of the
> > > report is,
> >
> > Interesting. The reason why we did not hit it on x86_64 is because
> > clear_page is implemented in asm (arch/x86/lib/clear_page_64.S) and
> > thus is not instrumented. Arm64 probably does the same. However, on
> > s390 clear_page is defined to memset.
>
> Can we define it to __memset() instead?
> __memset() is supposed to be ignored by KASAN, e.g. KASAN runtime uses
> it in the places where we don't care about bugs.
I suppose that could work if s390 maintains perfer this way.
next prev parent reply other threads:[~2020-06-10 12:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-10 5:21 [PATCH] mm/page_alloc: silence a KASAN false positive Qian Cai
2020-06-10 5:54 ` Dmitry Vyukov
2020-06-10 11:02 ` Alexander Potapenko
2020-06-10 12:28 ` Qian Cai [this message]
2020-06-10 12:26 ` Qian Cai
2020-06-23 8:48 ` Heiko Carstens
2020-06-30 12:33 ` Vasily Gorbik
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