Re: [Qemu-devel] [PULL 10/14] ui: fix VNC client throttling when audio capture is active

[Paolo Bonzini]

On 18/01/2018 15:12, Daniel P. Berrange wrote:
>> In addition to that, do we support a >= 2 GiB framebuffer at all? (Even
>> with unsigned ints, Coverity would rightly complain about a truncated
>> 32-bit multiplication being assigned to a 64-bit value).
> client_width/client_height are values that are initialized from the
> graphics card frontend config, and thus limited by amount of video
> RAM QEMU allows.   bytes_per_pixel is limited to 8/16/32.
> 
> So I think we're safe from 2GB overflow in any normal case.
> 
> That said, VGA RAM size is configurable, so I'm curious what would happen
> if someone configured an insanely large VGA RAM and asked for a big frame
> buffer in guest.
> 
> VNC is protocol limited to uint16 for width/height size, and so is X11
> so I imagine some exploding behavour would follow :-)

Indeed, and even 2^16 x 2^16 * 32bpp is already 34 bits.  So perhaps we
should limit VNC to 16384 pixels on each axis (maximum frame buffer size
1 GiB).

Paolo