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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 E5877C433FB for ; Mon, 22 Mar 2021 13:09:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C420D61992 for ; Mon, 22 Mar 2021 13:09:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233690AbhCVNIn (ORCPT ); Mon, 22 Mar 2021 09:08:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:47534 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230290AbhCVMy1 (ORCPT ); Mon, 22 Mar 2021 08:54:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 75DDE6191A; Mon, 22 Mar 2021 12:47:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1616417264; bh=Tm58TnChNl/jc/aRr3Ps8lOwEZ/u3ovewMnD333AJ3g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Np10NnhyNekAQzHlFKFGbC6fLpxO8Cn7EzyrlJBPck9PBvVqyI252G634AvBQXCzf vwnr6k93poY53/Jha8H6WrYCnDj8rfKTiAPLIOc3TVC1VLUJcTpcmmUMhhiwj1O5q1 kGO0kr2clKswle/JngwgJ/jq/U5ojvm1SgOkHsOE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vince Weaver , "Peter Zijlstra (Intel)" , Kan Liang Subject: [PATCH 4.9 18/25] perf/x86/intel: Fix a crash caused by zero PEBS status Date: Mon, 22 Mar 2021 13:29:08 +0100 Message-Id: <20210322121920.972540907@linuxfoundation.org> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210322121920.399826335@linuxfoundation.org> References: <20210322121920.399826335@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kan Liang commit d88d05a9e0b6d9356e97129d4ff9942d765f46ea upstream. A repeatable crash can be triggered by the perf_fuzzer on some Haswell system. https://lore.kernel.org/lkml/7170d3b-c17f-1ded-52aa-cc6d9ae999f4@maine.edu/ For some old CPUs (HSW and earlier), the PEBS status in a PEBS record may be mistakenly set to 0. To minimize the impact of the defect, the commit was introduced to try to avoid dropping the PEBS record for some cases. It adds a check in the intel_pmu_drain_pebs_nhm(), and updates the local pebs_status accordingly. However, it doesn't correct the PEBS status in the PEBS record, which may trigger the crash, especially for the large PEBS. It's possible that all the PEBS records in a large PEBS have the PEBS status 0. If so, the first get_next_pebs_record_by_bit() in the __intel_pmu_pebs_event() returns NULL. The at = NULL. Since it's a large PEBS, the 'count' parameter must > 1. The second get_next_pebs_record_by_bit() will crash. Besides the local pebs_status, correct the PEBS status in the PEBS record as well. Fixes: 01330d7288e0 ("perf/x86: Allow zero PEBS status with only single active event") Reported-by: Vince Weaver Suggested-by: Peter Zijlstra (Intel) Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1615555298-140216-1-git-send-email-kan.liang@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/events/intel/ds.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1473,7 +1473,7 @@ static void intel_pmu_drain_pebs_nhm(str */ if (!pebs_status && cpuc->pebs_enabled && !(cpuc->pebs_enabled & (cpuc->pebs_enabled-1))) - pebs_status = cpuc->pebs_enabled; + pebs_status = p->status = cpuc->pebs_enabled; bit = find_first_bit((unsigned long *)&pebs_status, x86_pmu.max_pebs_events);