From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758367Ab3EIWeq (ORCPT ); Thu, 9 May 2013 18:34:46 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46270 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758304Ab3EIWeo (ORCPT ); Thu, 9 May 2013 18:34:44 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andi Kleen , Peter Zijlstra , Ingo Molnar , eranian@google.com Subject: [ 05/26] perf/x86/intel/lbr: Fix LBR filter Date: Thu, 9 May 2013 15:34:19 -0700 Message-Id: <20130509223422.997735672@linuxfoundation.org> X-Mailer: git-send-email 1.8.3.rc0.20.gb99dd2e In-Reply-To: <20130509223422.368544659@linuxfoundation.org> References: <20130509223422.368544659@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra commit 6e15eb3ba6c0249c9e8c783517d131b47db995ca upstream. The LBR 'from' adddress is under full userspace control; ensure we validate it before reading from it. Note: is_module_text_address() can potentially be quite expensive; for those running into that with high overhead in modules optimize it using an RCU backed rb-tree. Reported-by: Andi Kleen Signed-off-by: Peter Zijlstra Cc: eranian@google.com Link: http://lkml.kernel.org/r/20130503121256.158211806@chello.nl Signed-off-by: Ingo Molnar Link: http://lkml.kernel.org/n/tip-mk8i82ffzax01cnqo829iy1q@git.kernel.org Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -442,8 +442,18 @@ static int branch_type(unsigned long fro return X86_BR_NONE; addr = buf; - } else - addr = (void *)from; + } else { + /* + * The LBR logs any address in the IP, even if the IP just + * faulted. This means userspace can control the from address. + * Ensure we don't blindy read any address by validating it is + * a known text address. + */ + if (kernel_text_address(from)) + addr = (void *)from; + else + return X86_BR_NONE; + } /* * decoder needs to know the ABI especially