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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 4C92BC04AA7 for ; Mon, 13 May 2019 10:07:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2921520873 for ; Mon, 13 May 2019 10:07:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728919AbfEMKHP (ORCPT ); Mon, 13 May 2019 06:07:15 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:59312 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728701AbfEMKHO (ORCPT ); Mon, 13 May 2019 06:07:14 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x4DA2dFK142090 for ; Mon, 13 May 2019 06:07:13 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2sf3dsynbj-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 13 May 2019 06:07:13 -0400 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 13 May 2019 11:07:07 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4DA76Kc48758894 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 May 2019 10:07:06 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 666B3A405B; Mon, 13 May 2019 10:07:06 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1B01CA4053; Mon, 13 May 2019 10:07:05 +0000 (GMT) Received: from [9.124.31.49] (unknown [9.124.31.49]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 13 May 2019 10:07:04 +0000 (GMT) Subject: Re: [PATCH 1/2] perf ioctl: Add check for the sample_period value To: Peter Zijlstra Cc: jolsa@redhat.com, mpe@ellerman.id.au, maddy@linux.vnet.ibm.com, acme@kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ravi Bangoria References: <20190511024217.4013-1-ravi.bangoria@linux.ibm.com> <20190513074213.GH2623@hirez.programming.kicks-ass.net> <20190513085620.GN2650@hirez.programming.kicks-ass.net> From: Ravi Bangoria Date: Mon, 13 May 2019 15:37:04 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190513085620.GN2650@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19051310-0012-0000-0000-0000031B1158 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19051310-0013-0000-0000-00002153A35B Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-13_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905130072 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/13/19 2:26 PM, Peter Zijlstra wrote: > On Mon, May 13, 2019 at 09:42:13AM +0200, Peter Zijlstra wrote: >> On Sat, May 11, 2019 at 08:12:16AM +0530, Ravi Bangoria wrote: >>> Add a check for sample_period value sent from userspace. Negative >>> value does not make sense. And in powerpc arch code this could cause >>> a recursive PMI leading to a hang (reported when running perf-fuzzer). >>> >>> Signed-off-by: Ravi Bangoria >>> --- >>> kernel/events/core.c | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/kernel/events/core.c b/kernel/events/core.c >>> index abbd4b3b96c2..e44c90378940 100644 >>> --- a/kernel/events/core.c >>> +++ b/kernel/events/core.c >>> @@ -5005,6 +5005,9 @@ static int perf_event_period(struct perf_event *event, u64 __user *arg) >>> if (perf_event_check_period(event, value)) >>> return -EINVAL; >>> >>> + if (!event->attr.freq && (value & (1ULL << 63))) >>> + return -EINVAL; >> >> Well, perf_event_attr::sample_period is __u64. Would not be the site >> using it as signed be the one in error? > > You forgot to mention commit: 0819b2e30ccb9, so I guess this just makes > it consistent and is fine. > Yeah, I was about to reply :)