From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934712AbbLPSFL (ORCPT ); Wed, 16 Dec 2015 13:05:11 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:49889 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966505AbbLPRk3 (ORCPT ); Wed, 16 Dec 2015 12:40:29 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Dave Hansen , Andrew Morton , Dave Hansen , "H. Peter Anvin" , Linus Torvalds , Peter Zijlstra , Ingo Molnar , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 006/128] x86/mpx: Add temporary variable to reduce masking Date: Wed, 16 Dec 2015 09:37:26 -0800 Message-Id: <1450287568-19808-7-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1450287568-19808-1-git-send-email-kamal@canonical.com> References: <1450287568-19808-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19.8-ckt12 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Dave Hansen commit a1149fc83a1f97612e72ec24a0bdbabff7b85e77 upstream. When we allocate a bounds table, we call mmap(), then add a "valid" bit to the value before storing it in to the bounds directory. If we fail along the way, we go and mask that valid bit _back_ out. That seems a little silly, and this makes it much more clear when we have a plain address versus an actual table _entry_. Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Andrew Morton Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20150607183704.3D69D5F4@viggo.jf.intel.com Signed-off-by: Ingo Molnar [ kamal: 3.19-stable prereq for "46561c3 x86/mpx: Do proper get_user() when running 32-bit binaries on 64-bit kernels" ] Signed-off-by: Kamal Mostafa --- arch/x86/mm/mpx.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 4d1c11c..9c208e4 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -409,6 +409,7 @@ static int allocate_bt(long __user *bd_entry) unsigned long expected_old_val = 0; unsigned long actual_old_val = 0; unsigned long bt_addr; + unsigned long bd_new_entry; int ret = 0; /* @@ -421,7 +422,7 @@ static int allocate_bt(long __user *bd_entry) /* * Set the valid flag (kinda like _PAGE_PRESENT in a pte) */ - bt_addr = bt_addr | MPX_BD_ENTRY_VALID_FLAG; + bd_new_entry = bt_addr | MPX_BD_ENTRY_VALID_FLAG; /* * Go poke the address of the new bounds table in to the @@ -435,7 +436,7 @@ static int allocate_bt(long __user *bd_entry) * of the MPX code that have to pagefault_disable(). */ ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry, - expected_old_val, bt_addr); + expected_old_val, bd_new_entry); if (ret) goto out_unmap; @@ -465,7 +466,7 @@ static int allocate_bt(long __user *bd_entry) } return 0; out_unmap: - vm_munmap(bt_addr & MPX_BT_ADDR_MASK, MPX_BT_SIZE_BYTES); + vm_munmap(bt_addr, MPX_BT_SIZE_BYTES); return ret; } -- 1.9.1