Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753855AbdGJIqr (ORCPT ); Mon, 10 Jul 2017 04:46:47 -0400 Received: from mail-oi0-f43.google.com ([209.85.218.43]:34686 "EHLO mail-oi0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753751AbdGJIqo (ORCPT ); Mon, 10 Jul 2017 04:46:44 -0400 MIME-Version: 1.0 In-Reply-To: <20170706220114.142438-3-ghackmann@google.com> References: <20170706220114.142438-1-ghackmann@google.com> <20170706220114.142438-3-ghackmann@google.com> From: Dmitry Vyukov Date: Mon, 10 Jul 2017 10:46:13 +0200 Message-ID: Subject: Re: [PATCH 2/4] kasan: added functions for unpoisoning stack variables To: Greg Hackmann Cc: Andrey Ryabinin , Alexander Potapenko , Masahiro Yamada , Michal Marek , LKML , kasan-dev , "linux-mm@kvack.org" , "open list:KERNEL BUILD + fi..." , Matthias Kaehlcke , Michael Davidson Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1856 Lines: 46 On Fri, Jul 7, 2017 at 12:01 AM, Greg Hackmann wrote: > From: Alexander Potapenko > > As a code-size optimization, LLVM builds since r279383 may > bulk-manipulate the shadow region when (un)poisoning large memory > blocks. This requires new callbacks that simply do an uninstrumented > memset(). > > This fixes linking the Clang-built kernel when using KASAN. > > Signed-off-by: Alexander Potapenko > [ghackmann@google.com: fix memset() parameters, and tweak > commit message to describe new callbacks] > Signed-off-by: Greg Hackmann > --- > mm/kasan/kasan.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c > index 892b626f564b..89911e5c69f9 100644 > --- a/mm/kasan/kasan.c > +++ b/mm/kasan/kasan.c > @@ -828,6 +828,21 @@ void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom) > } > EXPORT_SYMBOL(__asan_allocas_unpoison); > > +/* Emitted by the compiler to [un]poison local variables. */ > +#define DEFINE_ASAN_SET_SHADOW(byte) \ > + void __asan_set_shadow_##byte(const void *addr, size_t size) \ > + { \ > + __memset((void *)addr, 0x##byte, size); \ > + } \ > + EXPORT_SYMBOL(__asan_set_shadow_##byte) > + > +DEFINE_ASAN_SET_SHADOW(00); > +DEFINE_ASAN_SET_SHADOW(f1); > +DEFINE_ASAN_SET_SHADOW(f2); > +DEFINE_ASAN_SET_SHADOW(f3); > +DEFINE_ASAN_SET_SHADOW(f5); > +DEFINE_ASAN_SET_SHADOW(f8); > + > #ifdef CONFIG_MEMORY_HOTPLUG > static int kasan_mem_notifier(struct notifier_block *nb, > unsigned long action, void *data) Reviewed-by: Dmitry Vyukov