On (25/02/23 08:14), Herbert Xu wrote:
> On Sat, Feb 22, 2025 at 11:27:49PM +0900, Sergey Senozhatsky wrote:
> >
> > So I didn't look at all of them, but at least S/W lzo1 doesn't even
> > have a notion of max-output-len. lzo1x_1_compress() accepts a pointer
> > to out_len which tells the size of output stream (the algorithm is free
> > to produce any), so there is no dst_buf overflow as far as lzo1 is
> > concerned. Unless I'm missing something or misunderstanding your points.
>
> I just looked at deflate/zstd and they seem to be doing the right
> things.
>
> But yes lzo is a gaping security hole on the compression side.
Right, for lzo/lzo-rle we need a safety page.
It also seems that there is no common way of reporting dst_but overflow.
Some algos return -ENOSPC immediately, some don't return anything at all,
and deflate does it's own thing - there are these places where they see
they are out of out space but they Z_OK it
if (s->pending != 0) {
flush_pending(strm);
if (strm->avail_out == 0) {
/* Since avail_out is 0, deflate will be called again with
* more output space, but possibly with both pending and
* avail_in equal to zero. There won't be anything to do,
* but this is not an error situation so make sure we
* return OK instead of BUF_ERROR at next call of deflate:
*/
s->last_flush = -1;
return Z_OK;
}
}
