From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753979Ab0HRPIL (ORCPT ); Wed, 18 Aug 2010 11:08:11 -0400 Received: from kroah.org ([198.145.64.141]:47476 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753807Ab0HRPHh (ORCPT ); Wed, 18 Aug 2010 11:07:37 -0400 X-Mailbox-Line: From gregkh@clark.site Wed Aug 18 08:05:57 2010 Message-Id: <20100818150557.358157671@clark.site> User-Agent: quilt/0.48-11.2 Date: Wed, 18 Aug 2010 08:01:57 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk Subject: [3/6] x86: dont send SIGBUS for kernel page faults In-Reply-To: <20100818150615.GA4752@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ Based on commit 96054569190bdec375fe824e48ca1f4e3b53dd36 upstream, authored by Linus Torvalds. This is my backport to the .27 kernel tree, hopefully preserving the same functionality. Original commit message: It's wrong for several reasons, but the most direct one is that the fault may be for the stack accesses to set up a previous SIGBUS. When we have a kernel exception, the kernel exception handler does all the fixups, not some user-level signal handler. Even apart from the nested SIGBUS issue, it's also wrong to give out kernel fault addresses in the signal handler info block, or to send a SIGBUS when a system call already returns EFAULT. Cc: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/fault.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -589,6 +589,7 @@ void __kprobes do_page_fault(struct pt_r unsigned long address; int write, si_code; int fault; + int should_exit_no_context = 0; #ifdef CONFIG_X86_64 unsigned long flags; #endif @@ -876,6 +877,9 @@ no_context: oops_end(flags, regs, SIGKILL); #endif + if (should_exit_no_context) + return; + /* * We ran out of memory, or some other thing happened to us that made * us unable to handle the page fault gracefully. @@ -901,8 +905,11 @@ do_sigbus: up_read(&mm->mmap_sem); /* Kernel mode? Handle exceptions or die */ - if (!(error_code & PF_USER)) + if (!(error_code & PF_USER)) { + should_exit_no_context = 1; goto no_context; + } + #ifdef CONFIG_X86_32 /* User space => ok to do another page fault */ if (is_prefetch(regs, address, error_code))