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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,URIBL_SBL,URIBL_SBL_A 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 03668C433FF for ; Thu, 8 Aug 2019 09:09:33 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CCA042171F for ; Thu, 8 Aug 2019 09:09:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CCA042171F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47746 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hveQO-0000Lb-2I for qemu-devel@archiver.kernel.org; Thu, 08 Aug 2019 05:09:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45742) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hvePs-0007vQ-PH for qemu-devel@nongnu.org; Thu, 08 Aug 2019 05:09:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hvePr-00086w-I6 for qemu-devel@nongnu.org; Thu, 08 Aug 2019 05:09:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37330) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hvePr-00086d-D6 for qemu-devel@nongnu.org; Thu, 08 Aug 2019 05:08:59 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 55D918E585; Thu, 8 Aug 2019 09:08:58 +0000 (UTC) Received: from localhost.localdomain (unknown [10.65.150.157]) by smtp.corp.redhat.com (Postfix) with ESMTPS id ACA1419C69; Thu, 8 Aug 2019 09:08:55 +0000 (UTC) From: P J P To: Stefano Garzarella Date: Thu, 8 Aug 2019 14:36:52 +0530 Message-Id: <20190808090652.2478-1-ppandit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 08 Aug 2019 09:08:58 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2] scsi: lsi: exit infinite loop while executing script (CVE-2019-12068) X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Paolo Bonzini , Bugs SysSec , QEMU Developers , Prasad J Pandit Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Prasad J Pandit When executing script in lsi_execute_script(), the LSI scsi adapter emulator advances 's->dsp' index to read next opcode. This can lead to an infinite loop if the next opcode is empty. Exit such loop after reading 10k empty opcodes. Reported-by: Bugs SysSec Signed-off-by: Prasad J Pandit --- hw/scsi/lsi53c895a.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) Update v2: define LSI_MAX_INSN 10000 -> https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg01370.html diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c index 10468c1ec1..2adab341b1 100644 --- a/hw/scsi/lsi53c895a.c +++ b/hw/scsi/lsi53c895a.c @@ -185,6 +185,9 @@ static const char *names[] =3D { /* Flag set if this is a tagged command. */ #define LSI_TAG_VALID (1 << 16) =20 +/* Maximum instructions to process. */ +#define LSI_MAX_INSN 10000 + typedef struct lsi_request { SCSIRequest *req; uint32_t tag; @@ -1132,7 +1135,10 @@ static void lsi_execute_script(LSIState *s) =20 s->istat1 |=3D LSI_ISTAT1_SRUN; again: - insn_processed++; + if (++insn_processed > LSI_MAX_INSN) { + s->waiting =3D LSI_NOWAIT; + goto exitloop; + } insn =3D read_dword(s, s->dsp); if (!insn) { /* If we receive an empty opcode increment the DSP by 4 bytes @@ -1569,7 +1575,8 @@ again: } } } - if (insn_processed > 10000 && s->waiting =3D=3D LSI_NOWAIT) { +exitloop: + if (insn_processed > LSI_MAX_INSN && s->waiting =3D=3D LSI_NOWAIT) { /* Some windows drivers make the device spin waiting for a memor= y location to change. If we have been executed a lot of code t= hen assume this is the case and force an unexpected device discon= nect. --=20 2.21.0