[Qemu-devel] [Bug 1484925] Re: Segfault with custom vnc client

[Launchpad Bug Tracker]

[Expired for QEMU because there has been no activity for 60 days.]

** Changed in: qemu
       Status: Incomplete => Expired

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https://bugs.launchpad.net/bugs/1484925

Title:
  Segfault with custom vnc client

Status in QEMU:
  Expired

Bug description:
  Hey,

  I'm using Citrix XenServer 6.5. I worte a script that uses noVNC to
  connect to the rfb console via xapi. When I use GRML and try to boot
  it, the QEMU process segfaults and kills my VM. This happens when the
  screen resizes and the kernel is loading:

  recvfrom(3, "\3\1\0\0\0\0\2\200\1\220\3\0\2\200\0\0\0P\1\220", 4096, 0, NULL, 
NULL) = 20
  --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0xb28000} ---

  I can see in the child process the following message, right before the parent 
Segfaults:
  read(4, "cirrus: blanking the screen line_offset=0 height=480\n", 53) = 53

  This issue only happens, when I have my custom php/novnc-client
  connected. I also tried the nodejs/novnc package from xen-orchestra -
  same result. Using the stock client from Citrix XenCenter it works
  just fine. So I think it is related to noVNC. I hope this is just a
  bug and not exploitable to force a VM to crash or execute code.

  XenServer launches the qemu with the following command line:

  qemu-dm-25 --syslog -d 25 -m 2048 -boot dc -serial pty -vcpus 1
  -videoram 4 -vncunused -k en-us -vnc 127.0.0.1:1 -usb -usbdevice
  tablet -net nic,vlan=0,macaddr=8a:43:e2:b1:57:df,model=rtl8139 -net
  tap,vlan=0,bridge=xenbr0,ifname=tap25.0 -acpi -monitor pty

  XenServer 6.5 is using the following version:
  # /usr/lib64/xen/bin/qemu-dm -help
  QEMU PC emulator version 0.10.2, Copyright (c) 2003-2008 Fabrice Bellard

  Greetings
  Uli Stärk

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