From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5302DC43334 for ; Mon, 3 Sep 2018 17:17:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 180872077C for ; Mon, 3 Sep 2018 17:17:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 180872077C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730140AbeICViX (ORCPT ); Mon, 3 Sep 2018 17:38:23 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:42756 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728154AbeICViW (ORCPT ); Mon, 3 Sep 2018 17:38:22 -0400 Received: from localhost (ip-213-127-74-90.ip.prioritytelecom.net [213.127.74.90]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 54B82D10; Mon, 3 Sep 2018 17:17:17 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Paul Menzel , Thomas Gleixner , Alexander Shishkin , Arnaldo Carvalho de Melo , Borislav Petkov , Jiri Olsa , Linus Torvalds , Paul Menzel , Peter Zijlstra , Stephane Eranian , Vince Weaver , Ingo Molnar , Sasha Levin Subject: [PATCH 4.14 042/165] perf/x86/amd/ibs: Dont access non-started event Date: Mon, 3 Sep 2018 18:55:28 +0200 Message-Id: <20180903165657.250753353@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180903165655.003605184@linuxfoundation.org> References: <20180903165655.003605184@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner [ Upstream commit d2753e6b4882a637a0e8fb3b9c2e15f33265300e ] Paul Menzel reported the following bug: > Enabling the undefined behavior sanitizer and building GNU/Linux 4.18-rc5+ > (with some unrelated commits) with GCC 8.1.0 from Debian Sid/unstable, the > warning below is shown. > > > [ 2.111913] > > ================================================================================ > > [ 2.111917] UBSAN: Undefined behaviour in arch/x86/events/amd/ibs.c:582:24 > > [ 2.111919] member access within null pointer of type 'struct perf_event' > > [ 2.111926] CPU: 0 PID: 144 Comm: udevadm Not tainted 4.18.0-rc5-00316-g4864b68cedf2 #104 > > [ 2.111928] Hardware name: ASROCK E350M1/E350M1, BIOS TIMELESS 01/01/1970 > > [ 2.111930] Call Trace: > > [ 2.111943] dump_stack+0x55/0x89 > > [ 2.111949] ubsan_epilogue+0xb/0x33 > > [ 2.111953] handle_null_ptr_deref+0x7f/0x90 > > [ 2.111958] __ubsan_handle_type_mismatch_v1+0x55/0x60 > > [ 2.111964] perf_ibs_handle_irq+0x596/0x620 The code dereferences event before checking the STARTED bit. Patch below should cure the issue. The warning should not trigger, if I analyzed the thing correctly. (And Paul's testing confirms this.) Reported-by: Paul Menzel Tested-by: Paul Menzel Signed-off-by: Thomas Gleixner Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Jiri Olsa Cc: Linus Torvalds Cc: Paul Menzel Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Vince Weaver Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1807200958390.1580@nanos.tec.linutronix.de Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/events/amd/ibs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/arch/x86/events/amd/ibs.c +++ b/arch/x86/events/amd/ibs.c @@ -579,7 +579,7 @@ static int perf_ibs_handle_irq(struct pe { struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu); struct perf_event *event = pcpu->event; - struct hw_perf_event *hwc = &event->hw; + struct hw_perf_event *hwc; struct perf_sample_data data; struct perf_raw_record raw; struct pt_regs regs; @@ -602,6 +602,10 @@ fail: return 0; } + if (WARN_ON_ONCE(!event)) + goto fail; + + hwc = &event->hw; msr = hwc->config_base; buf = ibs_data.regs; rdmsrl(msr, *buf);