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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 D88B6C3A5A2 for ; Fri, 23 Aug 2019 09:32:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B11AE21726 for ; Fri, 23 Aug 2019 09:32:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732174AbfHWJcC (ORCPT ); Fri, 23 Aug 2019 05:32:02 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:7698 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726956AbfHWJcC (ORCPT ); Fri, 23 Aug 2019 05:32:02 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x7N9RY6Q101636 for ; Fri, 23 Aug 2019 05:32:01 -0400 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ujd4ps4ye-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 23 Aug 2019 05:32:00 -0400 Received: from localhost by e06smtp04.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) Fri, 23 Aug 2019 10:31:55 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x7N9Vrk451118266 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 23 Aug 2019 09:31:54 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DCD7C5204E; Fri, 23 Aug 2019 09:31:53 +0000 (GMT) Received: from [9.145.147.29] (unknown [9.145.147.29]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 9C77552050; Fri, 23 Aug 2019 09:31:53 +0000 (GMT) Subject: Re: [PATCH net] s390/qeth: reject oversized SNMP requests To: David Miller Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, Heiko Carstens , Stefan Raspl , Ursula Braun , Dan Carpenter References: <20190823092923.8507-1-jwi@linux.ibm.com> From: Julian Wiedmann Date: Fri, 23 Aug 2019 11:31:53 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190823092923.8507-1-jwi@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19082309-0016-0000-0000-000002A215B5 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19082309-0017-0000-0000-0000330252FB Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-23_03:,, 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=8.0.1-1906280000 definitions=main-1908230098 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org +cc Dan On 23.08.19 11:29, Julian Wiedmann wrote: > Commit d4c08afafa04 ("s390/qeth: streamline SNMP cmd code") removed > the bounds checking for req_len, under the assumption that the check in > qeth_alloc_cmd() would suffice. > > But that code path isn't sufficiently robust to handle a user-provided > data_length, which could overflow (when adding the cmd header overhead) > before being checked against QETH_BUFSIZE. We end up allocating just a > tiny iob, and the subsequent copy_from_user() writes past the end of > that iob. > > Special-case this path and add a coarse bounds check, to protect against > maliciuous requests. This let's the subsequent code flow do its normal > job and precise checking, without risk of overflow. > > Fixes: d4c08afafa04 ("s390/qeth: streamline SNMP cmd code") > Reported-by: Dan Carpenter > Signed-off-by: Julian Wiedmann > Reviewed-by: Ursula Braun > --- > drivers/s390/net/qeth_core_main.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c > index 9c3310c4d61d..6502b148541e 100644 > --- a/drivers/s390/net/qeth_core_main.c > +++ b/drivers/s390/net/qeth_core_main.c > @@ -4374,6 +4374,10 @@ static int qeth_snmp_command(struct qeth_card *card, char __user *udata) > get_user(req_len, &ureq->hdr.req_len)) > return -EFAULT; > > + /* Sanitize user input, to avoid overflows in iob size calculation: */ > + if (req_len > QETH_BUFSIZE) > + return -EINVAL; > + > iob = qeth_get_adapter_cmd(card, IPA_SETADP_SET_SNMP_CONTROL, req_len); > if (!iob) > return -ENOMEM; >