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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 9DA10C433B4 for ; Fri, 14 May 2021 19:32:10 +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 1F6236145D for ; Fri, 14 May 2021 19:32:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F6236145D 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]:52218 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lhdXd-0005g1-4T for qemu-devel@archiver.kernel.org; Fri, 14 May 2021 15:32:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59576) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lhdWW-0004uL-W1 for qemu-devel@nongnu.org; Fri, 14 May 2021 15:31:01 -0400 Received: from indium.canonical.com ([91.189.90.7]:43914) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lhdWV-0006PM-9E for qemu-devel@nongnu.org; Fri, 14 May 2021 15:31:00 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.93 #5 (Debian)) id 1lhdWR-0002FE-Ko for ; Fri, 14 May 2021 19:30:55 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 135382E820A for ; Fri, 14 May 2021 19:30:50 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Fri, 14 May 2021 19:24:11 -0000 From: Thomas Huth <1912780@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=In Progress; importance=High; assignee=None; X-Launchpad-Bug-Tags: cve security X-Launchpad-Bug-Information-Type: Public Security X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: yes X-Launchpad-Bug-Commenters: pjps X-Launchpad-Bug-Reporter: P J P (pjps) X-Launchpad-Bug-Modifier: Thomas Huth (th-huth) References: <161131902674.28690.10783050287084462937.malonedeb@soybean.canonical.com> Message-Id: <162102025205.21058.11647336541646820342.launchpad@soybean.canonical.com> Subject: [Bug 1912780] Re: QEMU: Null Pointer Failure in fdctrl_read() in hw/block/fdc.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="5321c3f40fa4d4b847f4e47fb766e7b95ed5036c"; Instance="production" X-Launchpad-Hash: c77ece257272890e4d7c301382cdc94d62d620fa 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=0.248, 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 1912780 <1912780@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" ** Changed in: qemu Status: New =3D> In Progress ** Changed in: qemu Importance: Undecided =3D> High -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1912780 Title: QEMU: Null Pointer Failure in fdctrl_read() in hw/block/fdc.c Status in QEMU: In Progress Bug description: [via qemu-security list] This is Gaoning Pan from Zhejiang University & Ant Security Light-Year La= b. I found a Null Pointer issue locates in fdctrl_read() in hw/block/fdc.c. This flaw allows a malicious guest user or process in a denial of service= condition. This issus was discovered in the latest Qemu-5.2.0. When using floppy dev= ice, there are several choices to get specific drive in get_drv(), depending on fdctrl->cur_drv.= But not all drives are initialized properly, leaving fdctrl->drives[0]->blk as NULL. So when the= drive was used in blk_pread(cur_drv->blk, fd_offset(cur_drv), fdctrl->fifo, BDRV_SECTOR_SIZ= E) at line 1918, null pointer access triggers, thus denial of service.My reproduced enviro= nment is as follows: Host: ubuntu 18.04 Guest: ubuntu 18.04 My boot command is as follows: qemu-system-x86_64 -enable-kvm -boot c -m 2G -drive format=3Dqcow2,file= =3D./ubuntu.img \ -nic user,hostfwd=3Dtcp:0.0.0.0:5555-:22 -device floppy,unit=3D1,drive= =3Dmydrive \ -drive id=3Dmydrive,file=3Dnull-co://,size=3D2M,format=3Draw,if=3Dnone= -display none ASAN output is as follows: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D14688=3D=3DERROR: AddressSanitizer: SEGV on unknown address 0x00000= 000034c (pc 0x5636eee9bbaf bp 0x7ff2a53fdea0 sp 0x7ff2a53fde90 T3) =3D=3D14688=3D=3DThe signal is caused by a WRITE memory access. =3D=3D14688=3D=3DHint: address points to the zero page. #0 0x5636eee9bbae in blk_inc_in_flight ../block/block-backend.c:1356 #1 0x5636eee9b766 in blk_prw ../block/block-backend.c:1328 #2 0x5636eee9cd76 in blk_pread ../block/block-backend.c:1491 #3 0x5636ee1adf24 in fdctrl_read_data ../hw/block/fdc.c:1918 #4 0x5636ee1a6654 in fdctrl_read ../hw/block/fdc.c:935 #5 0x5636eebb84c8 in portio_read ../softmmu/ioport.c:179 #6 0x5636ee9848c5 in memory_region_read_accessor ../softmmu/memory.c:= 442 #7 0x5636ee9855c2 in access_with_adjusted_size ../softmmu/memory.c:552 #8 0x5636ee98f0b7 in memory_region_dispatch_read1 ../softmmu/memory.c= :1420 #9 0x5636ee98f311 in memory_region_dispatch_read ../softmmu/memory.c:= 1449 #10 0x5636ee8ff64a in flatview_read_continue ../softmmu/physmem.c:2822 #11 0x5636ee8ff9e5 in flatview_read ../softmmu/physmem.c:2862 #12 0x5636ee8ffb83 in address_space_read_full ../softmmu/physmem.c:28= 75 #13 0x5636ee8ffdeb in address_space_rw ../softmmu/physmem.c:2903 #14 0x5636eea6a924 in kvm_handle_io ../accel/kvm/kvm-all.c:2285 #15 0x5636eea6c5e3 in kvm_cpu_exec ../accel/kvm/kvm-all.c:2531 #16 0x5636eeca492b in kvm_vcpu_thread_fn ../accel/kvm/kvm-cpus.c:49 #17 0x5636ef1bc296 in qemu_thread_start ../util/qemu-thread-posix.c:5= 21 #18 0x7ff337c736da in start_thread (/lib/x86_64-linux-gnu/libpthread.= so.0+0x76da) #19 0x7ff33799ca3e in __clone (/lib/x86_64-linux-gnu/libc.so.6+0x121a= 3e) AddressSanitizer can not provide additional info. SUMMARY: AddressSanitizer: SEGV ../block/block-backend.c:1356 in blk_inc_= in_flight Thread T3 created by T0 here: #0 0x7ff33c580d2f in __interceptor_pthread_create (/usr/lib/x86_64-li= nux-gnu/libasan.so.4+0x37d2f) #1 0x5636ef1bc673 in qemu_thread_create ../util/qemu-thread-posix.c:5= 58 #2 0x5636eeca4ce7 in kvm_start_vcpu_thread ../accel/kvm/kvm-cpus.c:73 #3 0x5636ee9aa965 in qemu_init_vcpu ../softmmu/cpus.c:622 #4 0x5636ee82a9b4 in x86_cpu_realizefn ../target/i386/cpu.c:6731 #5 0x5636eed002f4 in device_set_realized ../hw/core/qdev.c:886 #6 0x5636eecc59bc in property_set_bool ../qom/object.c:2251 #7 0x5636eecc0c28 in object_property_set ../qom/object.c:1398 #8 0x5636eecb6fb9 in object_property_set_qobject ../qom/qom-qobject.c= :28 #9 0x5636eecc1175 in object_property_set_bool ../qom/object.c:1465 #10 0x5636eecfc286 in qdev_realize ../hw/core/qdev.c:399 #11 0x5636ee739b34 in x86_cpu_new ../hw/i386/x86.c:111 #12 0x5636ee739d6d in x86_cpus_init ../hw/i386/x86.c:138 #13 0x5636ee6f843e in pc_init1 ../hw/i386/pc_piix.c:159 #14 0x5636ee6fab1e in pc_init_v5_2 ../hw/i386/pc_piix.c:438 #15 0x5636ee1cb4a7 in machine_run_board_init ../hw/core/machine.c:1134 #16 0x5636ee9c323d in qemu_init ../softmmu/vl.c:4369 #17 0x5636edd92c71 in main ../softmmu/main.c:49 #18 0x7ff33789cb96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.s= o.6+0x21b96) =3D=3D14688=3D=3DABORTING Reproducer is attached. Best regards. Gaoning Pan of Zhejiang University & Ant Security Light-Year Lab To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1912780/+subscriptions