From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757464AbbJIKSN (ORCPT ); Fri, 9 Oct 2015 06:18:13 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:38337 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753100AbbJIKSL (ORCPT ); Fri, 9 Oct 2015 06:18:11 -0400 MIME-Version: 1.0 In-Reply-To: <20151009094851.GA20507@leverpostej> References: <1442482692-6416-1-git-send-email-ryabinin.a.a@gmail.com> <20151007100411.GG3069@e104818-lin.cambridge.arm.com> <20151008111144.GC7275@leverpostej> <56165228.8060201@gmail.com> <20151008151144.GM17192@e104818-lin.cambridge.arm.com> <561789A2.5050601@gmail.com> <20151009094851.GA20507@leverpostej> Date: Fri, 9 Oct 2015 13:18:09 +0300 Message-ID: Subject: Re: [PATCH v6 0/6] KASAN for arm64 From: Andrey Ryabinin To: Mark Rutland Cc: Catalin Marinas , Ard Biesheuvel , "linux-efi@vger.kernel.org" , Arnd Bergmann , Yury , "linux-mm@kvack.org" , Linus Walleij , Mark Salter , Will Deacon , LKML , Alexey Klimov , Alexander Potapenko , Dmitry Vyukov , Andrey Konovalov , David Keitel , "linux-arm-kernel@lists.infradead.org" , Matt Fleming Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2015-10-09 12:48 GMT+03:00 Mark Rutland : > On Fri, Oct 09, 2015 at 12:32:18PM +0300, Andrey Ryabinin wrote: > [...] > >> I thought the EFI stub isolation patches create a copy of mem*() functions in the stub, >> but they are just create aliases with __efistub_ prefix. >> >> We only need to create some more aliases for KASAN. >> The following patch on top of the EFI stub isolation series works for me. >> >> >> Signed-off-by: Andrey Ryabinin >> --- >> arch/arm64/kernel/image.h | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h >> index e083af0..6eb8fee 100644 >> --- a/arch/arm64/kernel/image.h >> +++ b/arch/arm64/kernel/image.h >> @@ -80,6 +80,12 @@ __efistub_strcmp = __pi_strcmp; >> __efistub_strncmp = __pi_strncmp; >> __efistub___flush_dcache_area = __pi___flush_dcache_area; >> >> +#ifdef CONFIG_KASAN >> +__efistub___memcpy = __pi_memcpy; >> +__efistub___memmove = __pi_memmove; >> +__efistub___memset = __pi_memset; >> +#endif > > Ard's v4 stub isolation series has these aliases [1], as the stub > requires these aliases regardless of KASAN in order to link. Stub isolation series has __efistub_memcpy, not __efistub___memcpy (two additional '_'). The thing is, KASAN provides own implementation of memcpy() which checks memory before access. The original 'memcpy()' becomes __memcpy(), so we could still use it. In code that not instrumented by KASAN (like the EFI stub) we replace KASAN's memcpy() with the original __mempcy(): #define memcpy() __memcpy() So with CONFIG_KASAN=y the EFI stub uses __memcpy, thus we need to create the __efistub___memcpy alias. > > Thanks, > Mark. > > [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-October/375708.html