From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:52347 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752679AbbIKWke (ORCPT ); Fri, 11 Sep 2015 18:40:34 -0400 Subject: Patch "arm64/mm: Remove hack in mmap randomize layout" has been added to the 3.10-stable tree To: ydroneaud@opteya.com, anton@samba.org, benh@kernel.crashing.org, davem@davemloft.net, dpmcgee@gmail.com, gregkh@linuxfoundation.org, mbrugger@suse.com, will.deacon@arm.com Cc: , From: Date: Fri, 11 Sep 2015 15:40:32 -0700 Message-ID: <14420112327118@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled arm64/mm: Remove hack in mmap randomize layout to the 3.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm64-mm-remove-hack-in-mmap-randomize-layout.patch and it can be found in the queue-3.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From d6c763afab142a85e4770b4bc2a5f40f256d5c5d Mon Sep 17 00:00:00 2001 From: Yann Droneaud Date: Mon, 17 Nov 2014 23:02:19 +0000 Subject: arm64/mm: Remove hack in mmap randomize layout From: Yann Droneaud commit d6c763afab142a85e4770b4bc2a5f40f256d5c5d upstream. Since commit 8a0a9bd4db63 ('random: make get_random_int() more random'), get_random_int() returns a random value for each call, so comment and hack introduced in mmap_rnd() as part of commit 1d18c47c735e ('arm64: MMU fault handling and page table management') are incorrects. Commit 1d18c47c735e seems to use the same hack introduced by commit a5adc91a4b44 ('powerpc: Ensure random space between stack and mmaps'), latter copied in commit 5a0efea09f42 ('sparc64: Sharpen address space randomization calculations.'). But both architectures were cleaned up as part of commit fa8cbaaf5a68 ('powerpc+sparc64/mm: Remove hack in mmap randomize layout') as hack is no more needed since commit 8a0a9bd4db63. So the present patch removes the comment and the hack around get_random_int() on AArch64's mmap_rnd(). Cc: David S. Miller Cc: Anton Blanchard Cc: Benjamin Herrenschmidt Acked-by: Will Deacon Acked-by: Dan McGee Signed-off-by: Yann Droneaud Signed-off-by: Will Deacon Cc: Matthias Brugger Signed-off-by: Greg Kroah-Hartman --- arch/arm64/mm/mmap.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -47,22 +47,14 @@ static int mmap_is_legacy(void) return sysctl_legacy_va_layout; } -/* - * Since get_random_int() returns the same value within a 1 jiffy window, we - * will almost always get the same randomisation for the stack and mmap - * region. This will mean the relative distance between stack and mmap will be - * the same. - * - * To avoid this we can shift the randomness by 1 bit. - */ static unsigned long mmap_rnd(void) { unsigned long rnd = 0; if (current->flags & PF_RANDOMIZE) - rnd = (long)get_random_int() & (STACK_RND_MASK >> 1); + rnd = (long)get_random_int() & STACK_RND_MASK; - return rnd << (PAGE_SHIFT + 1); + return rnd << PAGE_SHIFT; } static unsigned long mmap_base(void) Patches currently in stable-queue which might be from ydroneaud@opteya.com are queue-3.10/arm64-mm-remove-hack-in-mmap-randomize-layout.patch