From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934228AbcBDWG5 (ORCPT ); Thu, 4 Feb 2016 17:06:57 -0500 Received: from mail-pf0-f181.google.com ([209.85.192.181]:34265 "EHLO mail-pf0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934114AbcBDWGv (ORCPT ); Thu, 4 Feb 2016 17:06:51 -0500 From: Daniel Cashman To: linux-kernel@vger.kernel.org Cc: linux@arm.linux.org.uk, akpm@linux-foundation.org, keescook@chromium.org, tytso@mit.edu, arnd@arndb.de, gregkh@linuxfoundation.org, catalin.marinas@arm.com, will.deacon@arm.com, ralf@linux-mips.org, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, viro@zeniv.linux.org.uk, nnk@google.com, jeffv@google.com, salyzyn@android.com, Daniel Cashman Subject: [PATCH 0/2] Fix mmap_base entropy for >31 bits. Date: Thu, 4 Feb 2016 14:06:29 -0800 Message-Id: <1454623591-17951-1-git-send-email-dcashman@android.com> X-Mailer: git-send-email 2.7.0.rc3.207.g0ac5344 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Upstream commit: d07e22597d1d355829b7b18ac19afa912cf758d1 added the ability to choose from a range of values to use for entropy count in generating the random offset to the mmap_base address. The maximum value on this range was set to 32 bits for 64-bit x86 systems, but this value could be increased further, requiring more than the 32 bits of randomness provided by get_random_int(), as is already possible for arm64. Add a new function: get_random_long() which more naturally fits with the mmap usage of get_random_int() but operates exactly the same as get_random_int(). Also, fix the shifting constant in mmap_rnd() to be an unsigned long so that values greater than 31 bits generate an appropriate mask without overflow. This is especially important on x86, as its shift instruction uses a 5-bit mask for the shift operand, which meant that any value for mmap_rnd_bits over 31 acts as a no-op and effectively disables mmap_base randomization. Finally, replace calls to get_random_int() with get_random_long() where appropriate. Daniel Cashman (2): drivers: char: random: Add get_random_long(). use get_random_long(). arch/arm/mm/mmap.c | 2 +- arch/arm64/mm/mmap.c | 4 ++-- arch/mips/mm/mmap.c | 4 ++-- arch/powerpc/kernel/process.c | 4 ++-- arch/powerpc/mm/mmap.c | 4 ++-- arch/sparc/kernel/sys_sparc_64.c | 2 +- arch/x86/mm/mmap.c | 6 +++--- drivers/char/random.c | 22 ++++++++++++++++++++++ fs/binfmt_elf.c | 2 +- include/linux/random.h | 1 + 10 files changed, 37 insertions(+), 14 deletions(-) -- 2.7.0.rc3.207.g0ac5344