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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 84F82C433DB for ; Wed, 24 Mar 2021 07:42:35 +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 A08D061477 for ; Wed, 24 Mar 2021 07:42:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A08D061477 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:36564 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lOy9x-0005zt-Nx for qemu-devel@archiver.kernel.org; Wed, 24 Mar 2021 03:42:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51852) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lOy8n-0005Ud-5w for qemu-devel@nongnu.org; Wed, 24 Mar 2021 03:41:21 -0400 Received: from indium.canonical.com ([91.189.90.7]:42736) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lOy8k-00022j-7k for qemu-devel@nongnu.org; Wed, 24 Mar 2021 03:41:20 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1lOy8i-0001AS-3m for ; Wed, 24 Mar 2021 07:41:16 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 1AEAE2E8055 for ; Wed, 24 Mar 2021 07:41:16 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Wed, 24 Mar 2021 07:31:22 -0000 From: P J P <1909247@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=New; importance=Undecided; assignee=None; X-Launchpad-Bug-Tags: cve fuzzer qemu security X-Launchpad-Bug-Information-Type: Public Security X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: yes X-Launchpad-Bug-Commenters: a1xndr mark-cave-ayland mauro-cascella pjps X-Launchpad-Bug-Reporter: Mauro Matteo Cascella (mauro-cascella) X-Launchpad-Bug-Modifier: P J P (pjps) References: <160882932286.4370.15587232403500958955.malonedeb@wampee.canonical.com> Message-Id: <161657108250.32717.5311086901810004029.malone@soybean.canonical.com> Subject: [Bug 1909247] Re: QEMU: use after free vulnerability in esp_do_dma() in hw/scsi/esp.c X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="4446feb642ca86be4f6eceb855b408397dad6a50"; Instance="production" X-Launchpad-Hash: ff668b90288a9c331e6728be40dee873397e3654 Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-Spam_score_int: -65 X-Spam_score: -6.6 X-Spam_bar: ------ X-Spam_report: (-6.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1909247 <1909247@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wednesday, 17 March, 2021, 10:26:36 pm IST, Cheolwoo Myung wrote: = > Hello PJP, Mauro > > Of course. you can post the details with our reproducers. = > I'm glad it helped you. > > Thank you. > - Cheolwoo Myung > 2021=EB=85=84 3=EC=9B=94 17=EC=9D=BC (=EC=88=98) =EC=98=A4=ED=9B=84 10:30, = P J P =EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1: > >On Monday, 15 March, 2021, 07:54:30 pm IST, Mauro Matteo Cascella wrote: = >>JFYI, CVE-2020-35506 was assigned to a very similar (if not the same) >>issue, see https://bugs.launchpad.net/qemu/+bug/1909247. > > * From the QEMU command lines below they do look similar. > = > * CVE bug above does not link to an upstream fix/patch. Maybe it's not fi= xed yet? > > >On Mon, Mar 15, 2021 at 6:58 AM P J P wrote: > >On Monday, 15 March, 2021, 11:11:14 am IST, Cheolwoo Myung wrote: > >Using hypervisor fuzzer, hyfuzz, I found a use-after-free issue in am53c= 974 emulator of QEMU enabled ASan. > > > ># To reproduce this issue, please run the QEMU process with the followin= g command line. > >$ ./qemu-system-i386 -m 512 -drive file=3D./hyfuzz.img,index=3D0,media= =3Ddisk,format=3Draw \ > > -device am53c974,id=3Dscsi -device scsi-hd,drive=3DSysDisk -drive >id= =3DSysDisk,if=3Dnone,file=3D./disk.img > > > > > > Using hypervisor fuzzer, hyfuzz, I found a stack buffer overflow issue = in am53c974 emulator of QEMU enabled ASan. > > > ># To reproduce this issue, please run the QEMU process with the followin= g command line. > >$ ./qemu-system-i386 -m 512 -drive file=3D./hyfuzz.img,index=3D0,media= =3Ddisk,format=3Draw \ > > -device am53c974,id=3Dscsi -device scsi-hd,drive=3DSysDisk -drive >id= =3DSysDisk,if=3Dnone,file=3D./disk.img > > * I was able to reproduce these issues against the latest upstream git sour= ce and following patch helps to fix above two issues. =3D=3D=3D $ git diff hw/scsi/ diff --git a/hw/scsi/esp-pci.c b/hw/scsi/esp-pci.c index c3d3dab05e..4a6f208069 100644 --- a/hw/scsi/esp-pci.c +++ b/hw/scsi/esp-pci.c @@ -98,6 +98,7 @@ static void esp_pci_handle_abort(PCIESPState *pci, uint32= _t val) trace_esp_pci_dma_abort(val); if (s->current_req) { scsi_req_cancel(s->current_req); + s->async_len =3D 0; } } = diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c index 507ab363bc..99bee7bc66 100644 --- a/hw/scsi/esp.c +++ b/hw/scsi/esp.c @@ -564,7 +564,7 @@ static void esp_do_dma(ESPState *s) int to_device =3D ((s->rregs[ESP_RSTAT] & 7) =3D=3D STAT_DO); uint8_t buf[ESP_CMDFIFO_SZ]; = - len =3D esp_get_tc(s); + len =3D MIN(esp_get_tc(s), sizeof(buf)); if (s->do_cmd) { /* =3D=3D=3D > >Using hypervisor fuzzer, hyfuzz, I found a heap buffer overflow issue in= am53c974 emulator of QEMU enabled ASan. > > > ># To reproduce this issue, please run the QEMU process with the followin= g command line. > >$ ./qemu-system-i386 -m 512 -drive file=3D./hyfuzz.img,index=3D0,media= =3Ddisk,format=3Draw \ > > -device am53c974,id=3Dscsi -device scsi-hd,drive=3DSysDisk -drive >id= =3DSysDisk,if=3Dnone,file=3D./disk.img * This heap OOB access issue seems to occur because static void do_busid_cmd(...) ... buf =3D (uint8_t *)fifo8_pop_buf(&s->cmdfifo, cmdlen, &n); <=3D=3D 'buf' points towards an end of the 32 byte buffer allocated via static void esp_init(Object *obj) ... fifo8_create(&s->cmdfifo, ESP_CMDFIFO_SZ(=3D32)); <=3D=3D and the OOB access could occur at numerous places, one of which is scsi_req_new -> scsi_req_parse_cdb -> memcpy(cmd->buf, buf, cmd->len); <=3D=3D buf=3D27, cmd->len=3D6 <=3D = 27+6 exceeds limit 32. * This one is quite tricky to fix. Because 'buf[]' is accessed at various places with hard coded index values. It's not easy to check access against 's->cmdfifo' object. @Cheolwoo: is it okay with you if we post above details and your reproducer= s on the upstream bug -> https://bugs.launchpad.net/qemu/+bug/1909247 It'll help to discuss/prepare a proper fix patch. Thank you. --- -P J P http://feedmug.com ** Attachment added: "hw-esp-oob-issues.zip" https://bugs.launchpad.net/qemu/+bug/1909247/+attachment/5480385/+files/= hw-esp-oob-issues.zip -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1909247 Title: QEMU: use after free vulnerability in esp_do_dma() in hw/scsi/esp.c Status in QEMU: New Bug description: A use-after-free vulnerability was found in the am53c974 SCSI host bus adapter emulation of QEMU. It could occur in the esp_do_dma() function in hw/scsi/esp.c while handling the 'Information Transfer' command (CMD_TI). A privileged guest user may abuse this flaw to crash the QEMU process on the host, resulting in a denial of service or potential code execution with the privileges of the QEMU process. This issue was reported by Cheolwoo Myung (Seoul National University). Original report: Using hypervisor fuzzer, hyfuzz, I found a use-after-free issue in am53c974 emulator of QEMU enabled ASan. It occurs while transferring information, as it does not check the buffer to be transferred. A malicious guest user/process could use this flaw to crash the QEMU process resulting in DoS scenario. To reproduce this issue, please run the QEMU with the following command line. # To enable ASan option, please set configuration with the following $ ./configure --target-list=3Di386-softmmu --disable-werror --enable-sani= tizers $ make # To reproduce this issue, please run the QEMU process with the following= command line $ ./qemu-system-i386 -m 512 -drive file=3D./hyfuzz.img,index=3D0,media=3D= disk,format=3Draw \ -device am53c974,id=3Dscsi -device scsi-hd,drive=3DSysDisk \ -drive id=3DSysDisk,if=3Dnone,file=3D./disk.img Please find attached the disk images to reproduce this issue. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1909247/+subscriptions