Re: [Qemu-devel] [PATCH] Fix scrambling of >32KB packets in slirp

[Kenneth Duda]

Well that is a good question.  When I made this patch, I wanted to
respect the comment in the code that the author felt that using a
signed data type was safer in some cases.  However, I will admit that
I do not understand this reasoning, and I agree that switching to an
unsigned data type would be better.  Would you like us to resubmit
this patch in that form?

   -Ken

On 5/1/06, Fabrice Bellard <address@hidden> wrote:
> Ed Swierk wrote:
> > In several places in qemu's slirp code, signed and unsigned ints are
> > used interchangeably when dealing with IP packet lengths and offsets.
> > This causes IP packets greater than 32K in length to be scrambled in
> > various interesting ways that are extremely difficult to troubleshoot.
> >
> > Although large IP packets are fairly rare in practice, certain
> > UDP-based protocols like NFS use them extensively.
> >
> > The attached patch wraps IP packet lengths and offsets in macros that
> > ensure they are always properly treated as unsigned values.
>
> Why not changing the definition itself to uint16_t and verifying each
> occurence of ip_off and ip_len ?
>
> Fabrice.
>
>
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