[Qemu-devel] [Bug 1637447] [NEW] VNC/RFB: QEMU reports incorrect name (length)

[cardamon]

Public bug reported:

If the name of a machine (as set with the -name argument) has a length
longer than 1024, (RFB) VNC clients will not receive a correct RFB
ServerInit message.

I suspect this is the problem:

https://github.com/qemu/qemu/blob/master/ui/vnc.c#L2463

The return value of snprintf is used as the value for the name-length field in 
the ServerInit message.
This is problematic for names that were truncated to 1024, as the length will 
now be bigger than the actual name.

I think a quick fix would be to simply report min(size,1024) to the
client...

** Affects: qemu
     Importance: Undecided
         Status: New


** Tags: rfb vnc

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https://bugs.launchpad.net/bugs/1637447

Title:
  VNC/RFB: QEMU reports incorrect name (length)

Status in QEMU:
  New

Bug description:
  If the name of a machine (as set with the -name argument) has a length
  longer than 1024, (RFB) VNC clients will not receive a correct RFB
  ServerInit message.

  I suspect this is the problem:

  https://github.com/qemu/qemu/blob/master/ui/vnc.c#L2463

  The return value of snprintf is used as the value for the name-length field 
in the ServerInit message.
  This is problematic for names that were truncated to 1024, as the length will 
now be bigger than the actual name.

  I think a quick fix would be to simply report min(size,1024) to the
  client...

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