Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755844AbbLGK00 (ORCPT ); Mon, 7 Dec 2015 05:26:26 -0500 Received: from hqemgate15.nvidia.com ([216.228.121.64]:5097 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755097AbbLGK0X convert rfc822-to-8bit (ORCPT ); Mon, 7 Dec 2015 05:26:23 -0500 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Mon, 07 Dec 2015 02:12:45 -0800 Subject: Re: [PATCH v5 3/4] arm64: mm: support ARCH_MMAP_RND_BITS. To: Daniel Cashman , References: <1449000658-11475-1-git-send-email-dcashman@android.com> <1449000658-11475-2-git-send-email-dcashman@android.com> <1449000658-11475-3-git-send-email-dcashman@android.com> <1449000658-11475-4-git-send-email-dcashman@android.com> CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , From: Jon Hunter Message-ID: <56655EC8.6030905@nvidia.com> Date: Mon, 7 Dec 2015 10:26:16 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <1449000658-11475-4-git-send-email-dcashman@android.com> X-Originating-IP: [10.21.132.159] X-ClientProxiedBy: UKMAIL101.nvidia.com (10.26.138.13) To UKMAIL101.nvidia.com (10.26.138.13) Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2561 Lines: 76 On 01/12/15 20:10, Daniel Cashman wrote: > From: dcashman > > arm64: arch_mmap_rnd() uses STACK_RND_MASK to generate the > random offset for the mmap base address. This value represents a > compromise between increased ASLR effectiveness and avoiding > address-space fragmentation. Replace it with a Kconfig option, which > is sensibly bounded, so that platform developers may choose where to > place this compromise. Keep default values as new minimums. > > Signed-off-by: Daniel Cashman > --- > arch/arm64/Kconfig | 31 +++++++++++++++++++++++++++++++ > arch/arm64/mm/mmap.c | 8 ++++++-- > 2 files changed, 37 insertions(+), 2 deletions(-) [snip] > diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c > index ed17747..af461b9 100644 > --- a/arch/arm64/mm/mmap.c > +++ b/arch/arm64/mm/mmap.c > @@ -51,8 +51,12 @@ unsigned long arch_mmap_rnd(void) > { > unsigned long rnd; > > - rnd = (unsigned long)get_random_int() & STACK_RND_MASK; > - > +ifdef CONFIG_COMPAT > + if (test_thread_flag(TIF_32BIT)) > + rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_compat_bits); > + else > +#endif > + rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_bits); > return rnd << PAGE_SHIFT; > } The above is causing a build failure on -next today. commit 42a6c8953112a9856dd09148c3d6a2cc106b6003 Author: Jon Hunter Date: Mon Dec 7 10:15:47 2015 +0000 ARM64: mm: Fix build failure caused by invalid ifdef statement Commit 2e4614190421 ("arm64-mm-support-arch_mmap_rnd_bits-v4") caused the following build failure due to a missing "#". Fix this. arch/arm64/mm/mmap.c: In function ?arch_mmap_rnd?: arch/arm64/mm/mmap.c:54:1: error: ?ifdef? undeclared (first use in this function) ifdef CONFIG_COMPAT ^ Signed-off-by: Jon Hunter diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index af461b935137..e59a75a308bc 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -51,7 +51,7 @@ unsigned long arch_mmap_rnd(void) { unsigned long rnd; -ifdef CONFIG_COMPAT +#ifdef CONFIG_COMPAT if (test_thread_flag(TIF_32BIT)) rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_compat_bits); else Cheers Jon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/