From patchwork Thu Sep 6 05:43:38 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 10589883 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1FD686CB for ; Thu, 6 Sep 2018 05:50:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0FA742A547 for ; Thu, 6 Sep 2018 05:50:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 043152A55B; Thu, 6 Sep 2018 05:50:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 986E32A547 for ; Thu, 6 Sep 2018 05:50:19 +0000 (UTC) Received: from localhost ([::1]:59481 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxnBL-0002wP-18 for patchwork-qemu-devel@patchwork.kernel.org; Thu, 06 Sep 2018 01:50:19 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59270) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxn8H-00087u-8Q for qemu-devel@nongnu.org; Thu, 06 Sep 2018 01:47:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fxn5N-0008WA-Vv for qemu-devel@nongnu.org; Thu, 06 Sep 2018 01:44:14 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:50558 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fxn5N-0008Um-NZ for qemu-devel@nongnu.org; Thu, 06 Sep 2018 01:44:09 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 54CB2402332F; Thu, 6 Sep 2018 05:44:09 +0000 (UTC) Received: from lemon.usersys.redhat.com (ovpn-12-55.pek2.redhat.com [10.72.12.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id E7CE6202322A; Thu, 6 Sep 2018 05:44:02 +0000 (UTC) From: Fam Zheng To: qemu-devel@nongnu.org Date: Thu, 6 Sep 2018 13:43:38 +0800 Message-Id: <20180906054340.28988-3-famz@redhat.com> In-Reply-To: <20180906054340.28988-1-famz@redhat.com> References: <20180906054340.28988-1-famz@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Thu, 06 Sep 2018 05:44:09 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Thu, 06 Sep 2018 05:44:09 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'famz@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH v2 2/4] slirp: Add sanity check for str option length X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Thomas Huth , Fam Zheng , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Gerd Hoffmann , Samuel Thibault , Paolo Bonzini , =?utf-8?q?Alex_Benn=C3=A9e?= , Brad Smith Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP When user provides a long domainname or hostname that doesn't fit in the DHCP packet, we mustn't overflow the response packet buffer. Instead, report errors, following the g_warning() in the slirp->vdnssearch branch. Also check the strlen against 256 when initializing slirp, which limit is also from the protocol where one byte represents the string length. This gives an early error before the warning which is harder to notice or diagnose. Reported-by: Thomas Huth Signed-off-by: Fam Zheng Reviewed-by: Thomas Huth --- net/slirp.c | 9 +++++++++ slirp/bootp.c | 32 ++++++++++++++++++++++---------- 2 files changed, 31 insertions(+), 10 deletions(-) diff --git a/net/slirp.c b/net/slirp.c index 1e14318b4d..fd21dc728c 100644 --- a/net/slirp.c +++ b/net/slirp.c @@ -365,6 +365,15 @@ static int net_slirp_init(NetClientState *peer, const char *model, return -1; } + if (vdomainname && strlen(vdomainname) > 255) { + error_setg(errp, "'domainname' parameter cannot exceed 255 bytes"); + return -1; + } + + if (vhostname && strlen(vhostname) > 255) { + error_setg(errp, "'vhostname' parameter cannot exceed 255 bytes"); + return -1; + } nc = qemu_new_net_client(&net_slirp_info, peer, model, name); diff --git a/slirp/bootp.c b/slirp/bootp.c index 9e7b53ba94..1e8185f0ec 100644 --- a/slirp/bootp.c +++ b/slirp/bootp.c @@ -159,6 +159,7 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp) struct in_addr preq_addr; int dhcp_msg_type, val; uint8_t *q; + uint8_t *end; uint8_t client_ethaddr[ETH_ALEN]; /* extract exact DHCP msg type */ @@ -240,6 +241,7 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp) rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */ q = rbp->bp_vend; + end = (uint8_t *)&rbp[1]; memcpy(q, rfc1533_cookie, 4); q += 4; @@ -292,24 +294,33 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp) if (*slirp->client_hostname) { val = strlen(slirp->client_hostname); - *q++ = RFC1533_HOSTNAME; - *q++ = val; - memcpy(q, slirp->client_hostname, val); - q += val; + if (q + val + 2 >= end) { + g_warning("DHCP packet size exceeded, " + "omitting host name option."); + } else { + *q++ = RFC1533_HOSTNAME; + *q++ = val; + memcpy(q, slirp->client_hostname, val); + q += val; + } } if (slirp->vdomainname) { val = strlen(slirp->vdomainname); - *q++ = RFC1533_DOMAINNAME; - *q++ = val; - memcpy(q, slirp->vdomainname, val); - q += val; + if (q + val + 2 >= end) { + g_warning("DHCP packet size exceeded, " + "omitting domain name option."); + } else { + *q++ = RFC1533_DOMAINNAME; + *q++ = val; + memcpy(q, slirp->vdomainname, val); + q += val; + } } if (slirp->vdnssearch) { - size_t spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend); val = slirp->vdnssearch_len; - if (val + 1 > spaceleft) { + if (q + val >= end) { g_warning("DHCP packet size exceeded, " "omitting domain-search option."); } else { @@ -331,6 +342,7 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp) memcpy(q, nak_msg, sizeof(nak_msg) - 1); q += sizeof(nak_msg) - 1; } + assert(q < end); *q = RFC1533_END; daddr.sin_addr.s_addr = 0xffffffffu;