Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752758AbdHVTKH (ORCPT ); Tue, 22 Aug 2017 15:10:07 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:43466 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752687AbdHVTKE (ORCPT ); Tue, 22 Aug 2017 15:10:04 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kees Cook , Kostya Serebryany , Will Deacon , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Andrew Morton , Linus Torvalds Subject: [PATCH 4.4 11/20] mm: revert x86_64 and arm64 ELF_ET_DYN_BASE base changes Date: Tue, 22 Aug 2017 12:09:54 -0700 Message-Id: <20170822190915.816065387@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170822190915.345029476@linuxfoundation.org> References: <20170822190915.345029476@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 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: 3416 Lines: 82 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook commit c715b72c1ba406f133217b509044c38d8e714a37 upstream. Moving the x86_64 and arm64 PIE base from 0x555555554000 to 0x000100000000 broke AddressSanitizer. This is a partial revert of: eab09532d400 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE") 02445990a96e ("arm64: move ELF_ET_DYN_BASE to 4GB / 4MB") The AddressSanitizer tool has hard-coded expectations about where executable mappings are loaded. The motivation for changing the PIE base in the above commits was to avoid the Stack-Clash CVEs that allowed executable mappings to get too close to heap and stack. This was mainly a problem on 32-bit, but the 64-bit bases were moved too, in an effort to proactively protect those systems (proofs of concept do exist that show 64-bit collisions, but other recent changes to fix stack accounting and setuid behaviors will minimize the impact). The new 32-bit PIE base is fine for ASan (since it matches the ET_EXEC base), so only the 64-bit PIE base needs to be reverted to let x86 and arm64 ASan binaries run again. Future changes to the 64-bit PIE base on these architectures can be made optional once a more dynamic method for dealing with AddressSanitizer is found. (e.g. always loading PIE into the mmap region for marked binaries.) Link: http://lkml.kernel.org/r/20170807201542.GA21271@beast Fixes: eab09532d400 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE") Fixes: 02445990a96e ("arm64: move ELF_ET_DYN_BASE to 4GB / 4MB") Signed-off-by: Kees Cook Reported-by: Kostya Serebryany Acked-by: Will Deacon Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/elf.h | 4 ++-- arch/x86/include/asm/elf.h | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -121,10 +121,10 @@ typedef struct user_fpsimd_state elf_fpr /* * This is the base location for PIE (ET_DYN with INTERP) loads. On - * 64-bit, this is raised to 4GB to leave the entire 32-bit address + * 64-bit, this is above 4GB to leave the entire 32-bit address * space open for things that want to use the area for 32-bit pointers. */ -#define ELF_ET_DYN_BASE 0x100000000UL +#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) /* * When the program starts, a1 contains a pointer to a function to be --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -247,11 +247,11 @@ extern int force_personality32; /* * This is the base location for PIE (ET_DYN with INTERP) loads. On - * 64-bit, this is raised to 4GB to leave the entire 32-bit address + * 64-bit, this is above 4GB to leave the entire 32-bit address * space open for things that want to use the area for 32-bit pointers. */ #define ELF_ET_DYN_BASE (mmap_is_ia32() ? 0x000400000UL : \ - 0x100000000UL) + (TASK_SIZE / 3 * 2)) /* This yields a mask that user programs can use to figure out what instruction set this CPU supports. This could be done in user space,