From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755986AbZFGOnd (ORCPT ); Sun, 7 Jun 2009 10:43:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755702AbZFGOnS (ORCPT ); Sun, 7 Jun 2009 10:43:18 -0400 Received: from hera.kernel.org ([140.211.167.34]:52876 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755633AbZFGOnR (ORCPT ); Sun, 7 Jun 2009 10:43:17 -0400 Date: Sun, 7 Jun 2009 14:42:33 GMT From: tip-bot for Lubomir Rintel To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, mingo@elte.hu, lkundrak@v3.sk Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, lkundrak@v3.sk, mingo@elte.hu In-Reply-To: <1244384628.2323.4.camel@bimbo> References: <1244384628.2323.4.camel@bimbo> Subject: [tip:x86/urgent] x86: Fix non-lazy GS handling in sys_vm86() Message-ID: Git-Commit-ID: 3aa6b186f86c5d06d6d92d14311ffed51f091f40 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Sun, 07 Jun 2009 14:42:47 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 3aa6b186f86c5d06d6d92d14311ffed51f091f40 Gitweb: http://git.kernel.org/tip/3aa6b186f86c5d06d6d92d14311ffed51f091f40 Author: Lubomir Rintel AuthorDate: Sun, 7 Jun 2009 16:23:48 +0200 Committer: Ingo Molnar CommitDate: Sun, 7 Jun 2009 16:31:23 +0200 x86: Fix non-lazy GS handling in sys_vm86() This fixes a stack corruption panic or null dereference oops due to a bad GS in resume_userspace() when returning from sys_vm86() and calling lockdep_sys_exit(). Only a problem when CONFIG_LOCKDEP and CONFIG_CC_STACKPROTECTOR enabled. Signed-off-by: Lubomir Rintel Cc: H. Peter Anvin LKML-Reference: <1244384628.2323.4.camel@bimbo> Signed-off-by: Ingo Molnar --- arch/x86/kernel/vm86_32.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c index d7ac84e..6a17769 100644 --- a/arch/x86/kernel/vm86_32.c +++ b/arch/x86/kernel/vm86_32.c @@ -287,10 +287,9 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk info->regs.pt.ds = 0; info->regs.pt.es = 0; info->regs.pt.fs = 0; - -/* we are clearing gs later just before "jmp resume_userspace", - * because it is not saved/restored. - */ +#ifndef CONFIG_X86_32_LAZY_GS + info->regs.pt.gs = 0; +#endif /* * The flags register is also special: we cannot trust that the user @@ -343,7 +342,9 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk __asm__ __volatile__( "movl %0,%%esp\n\t" "movl %1,%%ebp\n\t" +#ifdef CONFIG_X86_32_LAZY_GS "mov %2, %%gs\n\t" +#endif "jmp resume_userspace" : /* no outputs */ :"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0));