Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932404AbaGVWWl (ORCPT ); Tue, 22 Jul 2014 18:22:41 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:44340 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757144AbaGVWWe (ORCPT ); Tue, 22 Jul 2014 18:22:34 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: "H. Peter Anvin" , Kamal Mostafa Subject: [PATCH 3.8 012/116] x86-32, espfix: Remove filter for espfix32 due to race Date: Tue, 22 Jul 2014 15:20:23 -0700 Message-Id: <1406067727-19683-13-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1406067727-19683-1-git-send-email-kamal@canonical.com> References: <1406067727-19683-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.27 -stable review patch. If anyone has any objections, please let me know. ------------------ From: "H. Peter Anvin" commit 246f2d2ee1d715e1077fc47d61c394569c8ee692 upstream. It is not safe to use LAR to filter when to go down the espfix path, because the LDT is per-process (rather than per-thread) and another thread might change the descriptors behind our back. Fortunately it is always *safe* (if a bit slow) to go down the espfix path, and a 32-bit LDT stack segment is extremely rare. Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com Signed-off-by: Kamal Mostafa --- arch/x86/kernel/entry_32.S | 5 ----- 1 file changed, 5 deletions(-) diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 1d7fdbe..60d03c2 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -554,11 +554,6 @@ ENTRY(iret_exc) CFI_RESTORE_STATE ldt_ss: - larl PT_OLDSS(%esp), %eax - jnz restore_nocheck - testl $0x00400000, %eax # returning to 32bit stack? - jnz restore_nocheck # allright, normal return - #ifdef CONFIG_PARAVIRT /* * The kernel can't run on a non-flat stack if paravirt mode -- 1.9.1 -- 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/