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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 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 78898C433E3 for ; Thu, 23 Jul 2020 14:30:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5714C20771 for ; Thu, 23 Jul 2020 14:30:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="SIdFDBZU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729311AbgGWOa5 (ORCPT ); Thu, 23 Jul 2020 10:30:57 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:59942 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726715AbgGWOa4 (ORCPT ); Thu, 23 Jul 2020 10:30:56 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06NETc5f177210; Thu, 23 Jul 2020 14:30:35 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=sC9ikgxCdAId2FjwuAiIMWAdpmWMyGPubI1xPl1Ci74=; b=SIdFDBZUeQfxAJn2svTXpXwgZNNciCu1DUh7fq6b8KCb49Zf7f6z/Y1T2E7NA/UNpYvP pIIEYqWYl+/apLvEGx4+sWp+8ORDdOkk2UhKeoS8Gcdcc75aRZrU+TvuE6wEgfiCYHvo UegwsySFybvAMf7PJ1CKN1GY58g4WuoC6FwR9twka5FQBzQoUetCnCJjpDWtXltXJ5PH LFhdCFw1kAWuqUFY1FN+WvAWOlqt0Gi8csmGpUiEREPK1IiQKvjVqpk6R8Uexvgeb+Fx 3Bobs8VVJmID+kUba8DZXsSbVpHiKHQgLqUH7vOG6rOPI3LOGxVEQ1bfryMxdh/bRdxN NA== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2130.oracle.com with ESMTP id 32brgrsq45-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 23 Jul 2020 14:30:34 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06NESUwT081469; Thu, 23 Jul 2020 14:28:34 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 32fc4qgfae-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 23 Jul 2020 14:28:33 +0000 Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 06NESOmL023964; Thu, 23 Jul 2020 14:28:25 GMT Received: from kadam (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 23 Jul 2020 14:28:24 +0000 Date: Thu, 23 Jul 2020 17:28:15 +0300 From: Dan Carpenter To: Peilin Ye Cc: Joerg Reuter , Ralf Baechle , Greg Kroah-Hartman , syzkaller-bugs@googlegroups.com, linux-kernel-mentees@lists.linuxfoundation.org, "David S . Miller" , Jakub Kicinski , linux-hams@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [Linux-kernel-mentees] [PATCH net] AX.25: Fix out-of-bounds read in ax25_connect() Message-ID: <20200723142814.GQ2549@kadam> References: <20200722151901.350003-1-yepeilin.cs@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200722151901.350003-1-yepeilin.cs@gmail.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9690 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 malwarescore=0 suspectscore=0 mlxlogscore=999 adultscore=0 spamscore=0 bulkscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007230107 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9690 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 bulkscore=0 spamscore=0 impostorscore=0 suspectscore=0 adultscore=0 clxscore=1011 mlxlogscore=999 priorityscore=1501 phishscore=0 lowpriorityscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007230107 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 22, 2020 at 11:19:01AM -0400, Peilin Ye wrote: > Checks on `addr_len` and `fsa->fsa_ax25.sax25_ndigis` are insufficient. > ax25_connect() can go out of bounds when `fsa->fsa_ax25.sax25_ndigis` > equals to 7 or 8. Fix it. > > This issue has been reported as a KMSAN uninit-value bug, because in such > a case, ax25_connect() reaches into the uninitialized portion of the > `struct sockaddr_storage` statically allocated in __sys_connect(). > > It is safe to remove `fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS` because > `addr_len` is guaranteed to be less than or equal to > `sizeof(struct full_sockaddr_ax25)`. > > Reported-by: syzbot+c82752228ed975b0a623@syzkaller.appspotmail.com > Link: https://syzkaller.appspot.com/bug?id=55ef9d629f3b3d7d70b69558015b63b48d01af66 > Signed-off-by: Peilin Ye > --- > net/ax25/af_ax25.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c > index fd91cd34f25e..ef5bf116157a 100644 > --- a/net/ax25/af_ax25.c > +++ b/net/ax25/af_ax25.c > @@ -1187,7 +1187,9 @@ static int __must_check ax25_connect(struct socket *sock, > if (addr_len > sizeof(struct sockaddr_ax25) && > fsa->fsa_ax25.sax25_ndigis != 0) { > /* Valid number of digipeaters ? */ > - if (fsa->fsa_ax25.sax25_ndigis < 1 || fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS) { > + if (fsa->fsa_ax25.sax25_ndigis < 1 || > + addr_len < sizeof(struct sockaddr_ax25) + > + sizeof(ax25_address) * fsa->fsa_ax25.sax25_ndigis) { The "sizeof(ax25_address) * fsa->fsa_ax25.sax25_ndigis" can have an integer overflow so you still need the "fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS" check. regards, dan carpenter