Re: [PATCH v5 02/12] crypto: acomp - Define new interfaces for compress/decompress batching.

[Sergey Senozhatsky <senozhatsky@chromium.org>]

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;
	}
}