Re: [Qemu-devel] [PATCH] ui/vnc.c: Fix crash with VNC

[BALATON Zoltan]

On Mon, 12 Nov 2012, Gerd Hoffmann wrote:
> On 11/10/12 00:45, Marek Vasut wrote:
> > Dear Gerd Hoffmann,
> >
> > > On 11/09/12 10:50, Peter Maydell wrote:
> > > > On 9 November 2012 10:42, Anthony Liguori <address@hidden> wrote:
> > > > > While the abstract discussion is fun, it never hurts to be defensive.  I
> > > > > agree the root cause is vmware-vga but checking in vnc doesn't hurt.
> > > >
> > > > Defensive programming would suggest doing the clipping in the
> > > > console.c layer. That sounds a reasonable plan to me (especially
> > > > if we've hit similar problems multiple times in the past).
> > >
> > > Fully agree, I'll cook up a patch as I'm touching that anyway.
> > >
> > > Question is just whenever we'll go silently fixup stuff in console.c or
> > > use assert()s to enforce callers getting this correct.  I'd tend to use
> > > assert() as vmware-vga passing bogous stuff there IMHO indicates there
> > > is a bug in vmware-vga.
> >
> > Or rather some revisions of the guest X driver. Though it's worth investigating
> > it in the right place indeed.
>
> That too, but we must add a check to qemu nevertheless.  We can't trust
> the guest to not pass in bogous data, be it intentionally or by mistake.
> vmware-vga must sanity check the guest input no matter what, but
> validating the guests input once should be enougth.

For vmware_vga you could take this:
http://patchwork.ozlabs.org/patch/197904/
or modify it/come up with a similar patch as needed.

Regards,
BALATON Zoltan