[Qemu-devel] [Bug 1755912] Re: qemu-system-x86_64 crashed with SIGABRT when using option -vga qxl

[ Christian Ehrhardt ]

Running the Bionic ISO like:
$ qemu-system-x86_64 -cpu host -smp cores=4,threads=2 -boot d -m 2048 
-enable-kvm -vga qxl -vnc :21 -cdrom ubuntu-18.04-desktop-amd64.iso

Attaching like:
$ vncviewer FullColor=1 AutoSelect=0 10.245.168.42:5921
(alternatives on tigervnc)
Well for me it had "-k de" as well :-)

Then boot into the "try Ubuntu" live CD mode.
There opened a terminal to loop on xrandr.

Running the loop of above in that guest to crash it after a while.


Upgrade to proposed:
$ sudo apt install qemu-system-x86=1:2.11+dfsg-1ubuntu7.5
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Suggested packages:
  samba vde2 qemu-block-extra sgabios ovmf
The following packages will be upgraded:
  qemu-system-x86
1 upgraded, 0 newly installed, 0 to remove and 16 not upgraded.
Need to get 5.168 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu bionic-proposed/main amd64 
qemu-system-x86 amd64 1:2.11+dfsg-1ubuntu7.5 [5.168 kB]
Fetched 5.168 kB in 1s (7.666 kB/s)          
(Reading database ... 127990 files and directories currently installed.)
Preparing to unpack .../qemu-system-x86_1%3a2.11+dfsg-1ubuntu7.5_amd64.deb ...
Unpacking qemu-system-x86 (1:2.11+dfsg-1ubuntu7.5) over 
(1:2.11+dfsg-1ubuntu7.4) ...
Setting up qemu-system-x86 (1:2.11+dfsg-1ubuntu7.5) ...
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...


Running the loop again with the same setup  - no crash in 15 minutes - assume 
that means good now.
I'd be glad about someone else checking the result as well, best someone 
formerly affected by it.
(and having a tick in the eye for seeing my right screen change sizes and 
flicker all the time)

Setting verified

** Tags removed: verification-needed
** Tags added: verification-done

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https://bugs.launchpad.net/bugs/1755912

Title:
  qemu-system-x86_64 crashed with SIGABRT when using option -vga qxl

Status in QEMU:
  Fix Released
Status in qemu package in Ubuntu:
  Fix Released
Status in qemu source package in Bionic:
  Fix Committed

Bug description:
  [Impact]

   * There are conditions where the vga/qxl driver can crash the qemu 
     process.

   * It is like a very complex case of a non initialized var - without the 
     fix it might try to ask for updates without having a valid primary 
     surface.

   * Backport from upstream
  
https://git.qemu.org/?p=qemu.git;a=commit;h=5bd5c27c7d284d01477c5cc022ce22438c46bf9f
  to avoid the crash

  
  [Test Case]

   * Sometimes booting xubuntu was reported to be enough, at other times
  it was needed to change resolution a few times to trigger.

    # get xubuntu iso (actually other UI Isos should do as well)
    $ qemu-system-x86_64 -vga qxl -enable-kvm -cpu host -smp cores=2,threads=2 
-m 2048 -cdrom xubuntu-18.04-desktop-amd64.iso
    # If it boots successfully, change resolution until it crashes.
    $ while true ; do xrandr --output Virtual-0 --mode 640x480 ; sleep 1 ; 
xrandr --output Virtual-0 --mode 1280x720 ; sleep 1 ; xrandr --output Virtual-0 
--mode 1920x1080 ; sleep 1 ; done

   * Without the fix that will trigger the qemu crash

  [Regression Potential]

   * The change "just" adds QXL_MODE_UNDEFINED as one more trigger to leave 
     the rendering update. That sounds rather safe. But thinking hard on 
     potential updates I could think of theoretical setups that were  in 
     undefined mode all the time (unlikely or impossible I think) that now 
     would get no updates anymore. Well I really don't think this is an 
     issue, but since this section should be open thinking on "potential" 
     regressions that is what comes to my mind.

  [Other Info]
   
   * Thanks to Leonardo for most of the bisecting and discussion work!

  
  ---

  
  When using qemu-system-x86_64 with the option -vga qxl, it crashes. The 
easiest way to crash it is by trying to change the guest's resolution. However, 
the system may randomly crash too, not happening only when changing resolution. 
Here is the terminal output of one of these random crashes:

  --------

  $ qemu-system-x86_64 -hda /dev/sdb -m 2048 -enable-kvm -cpu host -vga qxl 
-nodefaults -netdev user,id=hostnet0 -device 
virtio-net-pci,id=net0,netdev=hostnet0
  WARNING: Image format was not specified for '/dev/sdb' and probing guessed 
raw.
           Automatically detecting the format is dangerous for raw images, 
write operations on block 0 will be restricted.
           Specify the 'raw' format explicitly to remove the restrictions.

  (process:21313): Spice-WARNING **: 16:01:45.759: display-
  channel.c:2431:display_channel_validate_surface: canvas address is
  0x7f8eb948ab18 for 0 (and is NULL)

  (process:21313): Spice-WARNING **: 16:01:45.759: display-
  channel.c:2432:display_channel_validate_surface: failed on 0

  (process:21313): Spice-CRITICAL **: 16:01:45.759: 
display-channel.c:2035:display_channel_update: condition 
`display_channel_validate_surface(display, surface_id)' failed
  Abortado (imagem do núcleo gravada)

  --------

  I was running QEMU as a normal user which is on the groups kvm and
  disk. Initially I supposed the problem was because I was running QEMU
  as root, but as a normal user this happens too.

  I have tested with guests with different Ubuntu version: 18.04, 17.10
  and 16.04. It is happening with them all.

  ProblemType: Crash
  DistroRelease: Ubuntu 18.04
  Package: qemu-system-x86 1:2.11+dfsg-1ubuntu4
  ProcVersionSignature: Ubuntu 4.15.0-10.11-generic 4.15.3
  Uname: Linux 4.15.0-10-generic x86_64
  ApportVersion: 2.20.8-0ubuntu10
  Architecture: amd64
  CurrentDesktop: XFCE
  Date: Wed Mar 14 17:13:52 2018
  ExecutablePath: /usr/bin/qemu-system-x86_64
  InstallationDate: Installed on 2017-06-13 (273 days ago)
  InstallationMedia: Xubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
  KvmCmdLine: COMMAND         STAT  EUID  RUID   PID  PPID %CPU COMMAND
  MachineType: LENOVO 80UG
  ProcCmdline: qemu-system-x86_64 -hda /dev/sdb -smp cpus=2 -m 512 -enable-kvm 
-cpu host -vga qxl -nodefaults -netdev user,id=hostnet0 -device 
virtio-net-pci,id=net0,netdev=hostnet0
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-10-generic.efi.signed 
root=UUID=6b4ae5c0-c78c-49a6-a1ba-029192618a7a ro quiet
  Signal: 6
  SourcePackage: qemu
  StacktraceTop:
   () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1
   () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1
   () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1
   () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1
   () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1
  Title: qemu-system-x86_64 crashed with SIGABRT
  UpgradeStatus: Upgraded to bionic on 2017-10-20 (145 days ago)
  UserGroups: adm bluetooth cdrom dialout dip disk kvm libvirt lpadmin netdev 
plugdev sambashare sudo
  dmi.bios.date: 07/10/2017
  dmi.bios.vendor: LENOVO
  dmi.bios.version: 0XCN43WW
  dmi.board.asset.tag: NO Asset Tag
  dmi.board.name: Toronto 4A2
  dmi.board.vendor: LENOVO
  dmi.board.version: SDK0J40679 WIN
  dmi.chassis.asset.tag: NO Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Lenovo ideapad 310-14ISK
  dmi.modalias: 
dmi:bvnLENOVO:bvr0XCN43WW:bd07/10/2017:svnLENOVO:pn80UG:pvrLenovoideapad310-14ISK:rvnLENOVO:rnToronto4A2:rvrSDK0J40679WIN:cvnLENOVO:ct10:cvrLenovoideapad310-14ISK:
  dmi.product.family: IDEAPAD
  dmi.product.name: 80UG
  dmi.product.version: Lenovo ideapad 310-14ISK
  dmi.sys.vendor: LENOVO

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