Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754866Ab3CATry (ORCPT ); Fri, 1 Mar 2013 14:47:54 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:52090 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754709Ab3CATqz (ORCPT ); Fri, 1 Mar 2013 14:46:55 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Rosenberg , Brad Spengler , Kees Cook , "H. Peter Anvin" , "Paul E. McKenney" , Frederic Weisbecker , "Eric W. Biederman" , Linus Torvalds , Andrew Morton , Peter Zijlstra , Ingo Molnar , CAI Qian Subject: [ 22/30] x86: Do not leak kernel page mapping locations Date: Fri, 1 Mar 2013 11:45:43 -0800 Message-Id: <20130301194530.386673314@linuxfoundation.org> X-Mailer: git-send-email 1.8.1.rc1.5.g7e0651a In-Reply-To: <20130301194527.988540148@linuxfoundation.org> References: <20130301194527.988540148@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2400 Lines: 67 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook commit e575a86fdc50d013bf3ad3aa81d9100e8e6cc60d upstream. Without this patch, it is trivial to determine kernel page mappings by examining the error code reported to dmesg[1]. Instead, declare the entire kernel memory space as a violation of a present page. Additionally, since show_unhandled_signals is enabled by default, switch branch hinting to the more realistic expectation, and unobfuscate the setting of the PF_PROT bit to improve readability. [1] http://vulnfactory.org/blog/2013/02/06/a-linux-memory-trick/ Reported-by: Dan Rosenberg Suggested-by: Brad Spengler Signed-off-by: Kees Cook Acked-by: H. Peter Anvin Cc: Paul E. McKenney Cc: Frederic Weisbecker Cc: Eric W. Biederman Cc: Linus Torvalds Cc: Andrew Morton Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20130207174413.GA12485@www.outflux.net Signed-off-by: Ingo Molnar Signed-off-by: CAI Qian Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/fault.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -720,12 +720,15 @@ __bad_area_nosemaphore(struct pt_regs *r if (is_errata100(regs, address)) return; - if (unlikely(show_unhandled_signals)) + /* Kernel addresses are always protection faults: */ + if (address >= TASK_SIZE) + error_code |= PF_PROT; + + if (likely(show_unhandled_signals)) show_signal_msg(regs, error_code, address, tsk); - /* Kernel addresses are always protection faults: */ tsk->thread.cr2 = address; - tsk->thread.error_code = error_code | (address >= TASK_SIZE); + tsk->thread.error_code = error_code; tsk->thread.trap_no = 14; force_sig_info_fault(SIGSEGV, si_code, address, tsk, 0); -- 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/