[Group.of.nepali.translators] [Bug 1743637] Re: QEMU vhost-user shutdown suffers from use after free (missing clean shutdown)
This bug was fixed in the package qemu - 1:2.5+dfsg-5ubuntu10.28 --- qemu (1:2.5+dfsg-5ubuntu10.28) xenial-security; urgency=medium * SECURITY UPDATE: arbitrary code execution via load_multiboot - debian/patches/CVE-2018-7550.patch: handle bss_end_addr being zero in hw/i386/multiboot.c. - CVE-2018-7550 -- Marc Deslauriers Fri, 11 May 2018 13:34:24 -0400 ** Changed in: qemu (Ubuntu Xenial) Status: Fix Committed => Fix Released ** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2018-7550 -- You received this bug notification because you are a member of नेपाली भाषा समायोजकहरुको समूह, which is subscribed to Xenial. Matching subscriptions: Ubuntu 16.04 Bugs https://bugs.launchpad.net/bugs/1743637 Title: QEMU vhost-user shutdown suffers from use after free (missing clean shutdown) Status in qemu package in Ubuntu: Fix Released Status in qemu source package in Xenial: Fix Released Bug description: [Impact] * vhost-user resources aren't cleaned on QEMU shutdown * this can lead to memory leak (specially bad if hugepages) * QEMU bad assertion blocks the cleanup logic [Test Case] * to use QEMU with vhost-user and stress test the shutdown * eventually the faulty logic (race on the variable "name") will happen [Regression Potential] * based on upstream code * based on core dump analysis * could make qemu vhost-user virtio nic shutdown even worse [Other Info] * Check initial case description: # BUG Description after dump analysis - The logic net_cleanup calls the vhost_net_stop. - This last one iterates over all vhost networks to stop one by one. - Idea behind is to cleanly do the virtqueue stop, releasing resources. - In order to stop the virtqueue, vhost has to get the vring base address (by sending a msg of VHOST_USER_GET_VERING_BASE) - the char device would read from the socket the base address. - if it reads nothing, the qemu tcp channel driver would disconnect the socket. - when the socket is disconnected, vhost_user stops all the queues to that vhost_user socket. From the dump: By disconnecting charnet2 device we reach the error. Since the char device has already been disconnected, the vhost_user_stop tries to stop all queues but it accidentally treats all of them the same (and charnet4 is a TAP device, not a VHOST USER). Logic Error: Here is the charnet2 data at the time of the error: Name : filename (from CharDriverState) Details:0x556a934b0a90 "disconnected:unix:/run/openvswitch/vhostuser-vcic" Default:0x556a934b0a90 "disconnected:unix:/run/openvswitch/vhostuser-vcic" Decimal:93916226062992 Hex:0x556a934b0a90 Binary:101010101101010100100110100101110101001 Octal:02526522322605220 When it realizes the connection is gone it creates an event: qemu_chr_be_event(chr, CHR_EVENT_CLOSED); Which will call: net_vhost_user_event This last function finds all NetClientState using a pointer called "name". The event was originated the device charnet2 and the event callback is running using charnet4, which explains why the bad decision (assert) was made (trying to assert if a TAP device is a VHOST_USER one). Possible Fix There is already a commit upstream that might address this: commit c1bf3531aecf4a0ba25bb150dd5fe21edf406c88 Author: Marc-André Lureau 2016-02-23 18:10:49 Committer: Michael S. Tsirkin 2016-03-11 14:59:12 Branches: master, origin/HEAD, origin/master, origin/stable-2.10, origin/stable-2.6, origin/stable-2.7, origin/stable-2.8, origin/stable-2.9 vhost-user: fix use after free "name" is freed after visiting options, instead use the first NetClientState name. Adds a few assert() for clarifying and checking some impossible states. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1743637/+subscriptions ___ Mailing list: https://launchpad.net/~group.of.nepali.translators Post to : group.of.nepali.translators@lists.launchpad.net Unsubscribe : https://launchpad.net/~group.of.nepali.translators More help : https://help.launchpad.net/ListHelp
[Group.of.nepali.translators] [Bug 1743637] Re: QEMU vhost-user shutdown suffers from use after free (missing clean shutdown)
** Changed in: qemu (Ubuntu Xenial) Status: New => In Progress ** Changed in: qemu (Ubuntu) Status: In Progress => Fix Released ** Changed in: qemu (Ubuntu) Assignee: Rafael David Tinoco (inaddy) => (unassigned) ** Changed in: qemu (Ubuntu Xenial) Assignee: (unassigned) => Rafael David Tinoco (inaddy) ** Changed in: qemu (Ubuntu Xenial) Importance: Undecided => Medium -- You received this bug notification because you are a member of नेपाली भाषा समायोजकहरुको समूह, which is subscribed to Xenial. Matching subscriptions: Ubuntu 16.04 Bugs https://bugs.launchpad.net/bugs/1743637 Title: QEMU vhost-user shutdown suffers from use after free (missing clean shutdown) Status in qemu package in Ubuntu: Fix Released Status in qemu source package in Xenial: In Progress Bug description: # BUG Description after dump analysis - The logic net_cleanup calls the vhost_net_stop. - This last one iterates over all vhost networks to stop one by one. - Idea behind is to cleanly do the virtqueue stop, releasing resources. - In order to stop the virtqueue, vhost has to get the vring base address (by sending a msg of VHOST_USER_GET_VERING_BASE) - the char device would read from the socket the base address. - if it reads nothing, the qemu tcp channel driver would disconnect the socket. - when the socket is disconnected, vhost_user stops all the queues to that vhost_user socket. From the dump: By disconnecting charnet2 device we reach the error. Since the char device has already been disconnected, the vhost_user_stop tries to stop all queues but it accidentally treats all of them the same (and charnet4 is a TAP device, not a VHOST USER). Logic Error: Here is the charnet2 data at the time of the error: Name : filename (from CharDriverState) Details:0x556a934b0a90 "disconnected:unix:/run/openvswitch/vhostuser-vcic" Default:0x556a934b0a90 "disconnected:unix:/run/openvswitch/vhostuser-vcic" Decimal:93916226062992 Hex:0x556a934b0a90 Binary:101010101101010100100110100101110101001 Octal:02526522322605220 When it realizes the connection is gone it creates an event: qemu_chr_be_event(chr, CHR_EVENT_CLOSED); Which will call: net_vhost_user_event This last function finds all NetClientState using a pointer called "name". The event was originated the device charnet2 and the event callback is running using charnet4, which explains why the bad decision (assert) was made (trying to assert if a TAP device is a VHOST_USER one). Possible Fix There is already a commit upstream that might address this: commit c1bf3531aecf4a0ba25bb150dd5fe21edf406c88 Author: Marc-André Lureau 2016-02-23 18:10:49 Committer: Michael S. Tsirkin 2016-03-11 14:59:12 Branches: master, origin/HEAD, origin/master, origin/stable-2.10, origin/stable-2.6, origin/stable-2.7, origin/stable-2.8, origin/stable-2.9 vhost-user: fix use after free "name" is freed after visiting options, instead use the first NetClientState name. Adds a few assert() for clarifying and checking some impossible states. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1743637/+subscriptions ___ Mailing list: https://launchpad.net/~group.of.nepali.translators Post to : group.of.nepali.translators@lists.launchpad.net Unsubscribe : https://launchpad.net/~group.of.nepali.translators More help : https://help.launchpad.net/ListHelp
[Group.of.nepali.translators] [Bug 1743637] Re: QEMU vhost-user shutdown suffers from use after free (missing clean shutdown)
** Also affects: qemu (Ubuntu Xenial) Importance: Undecided Status: New -- You received this bug notification because you are a member of नेपाली भाषा समायोजकहरुको समूह, which is subscribed to Xenial. Matching subscriptions: Ubuntu 16.04 Bugs https://bugs.launchpad.net/bugs/1743637 Title: QEMU vhost-user shutdown suffers from use after free (missing clean shutdown) Status in qemu package in Ubuntu: Fix Released Status in qemu source package in Xenial: In Progress Bug description: # BUG Description after dump analysis - The logic net_cleanup calls the vhost_net_stop. - This last one iterates over all vhost networks to stop one by one. - Idea behind is to cleanly do the virtqueue stop, releasing resources. - In order to stop the virtqueue, vhost has to get the vring base address (by sending a msg of VHOST_USER_GET_VERING_BASE) - the char device would read from the socket the base address. - if it reads nothing, the qemu tcp channel driver would disconnect the socket. - when the socket is disconnected, vhost_user stops all the queues to that vhost_user socket. From the dump: By disconnecting charnet2 device we reach the error. Since the char device has already been disconnected, the vhost_user_stop tries to stop all queues but it accidentally treats all of them the same (and charnet4 is a TAP device, not a VHOST USER). Logic Error: Here is the charnet2 data at the time of the error: Name : filename (from CharDriverState) Details:0x556a934b0a90 "disconnected:unix:/run/openvswitch/vhostuser-vcic" Default:0x556a934b0a90 "disconnected:unix:/run/openvswitch/vhostuser-vcic" Decimal:93916226062992 Hex:0x556a934b0a90 Binary:101010101101010100100110100101110101001 Octal:02526522322605220 When it realizes the connection is gone it creates an event: qemu_chr_be_event(chr, CHR_EVENT_CLOSED); Which will call: net_vhost_user_event This last function finds all NetClientState using a pointer called "name". The event was originated the device charnet2 and the event callback is running using charnet4, which explains why the bad decision (assert) was made (trying to assert if a TAP device is a VHOST_USER one). Possible Fix There is already a commit upstream that might address this: commit c1bf3531aecf4a0ba25bb150dd5fe21edf406c88 Author: Marc-André Lureau 2016-02-23 18:10:49 Committer: Michael S. Tsirkin 2016-03-11 14:59:12 Branches: master, origin/HEAD, origin/master, origin/stable-2.10, origin/stable-2.6, origin/stable-2.7, origin/stable-2.8, origin/stable-2.9 vhost-user: fix use after free "name" is freed after visiting options, instead use the first NetClientState name. Adds a few assert() for clarifying and checking some impossible states. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1743637/+subscriptions ___ Mailing list: https://launchpad.net/~group.of.nepali.translators Post to : group.of.nepali.translators@lists.launchpad.net Unsubscribe : https://launchpad.net/~group.of.nepali.translators More help : https://help.launchpad.net/ListHelp