Re: [PATCH 5/8] pstore: Fix long-term implicit conversions in the compression routines

From: Kees Cook
Date: Fri Oct 07 2022 - 15:37:49 EST


On Fri, Oct 07, 2022 at 10:47:01AM +0200, Ard Biesheuvel wrote:
> On Fri, 7 Oct 2022 at 01:36, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> >
> > On Thu, Oct 06, 2022 at 07:42:09PM -0300, Guilherme G. Piccoli wrote:
> > > The pstore infrastructure is capable of compressing collected logs,
> > > relying for that in many compression "libraries" present on kernel.
> > > Happens that the (de)compression code in pstore performs many
> > > implicit conversions from unsigned int/size_t to int, and vice-versa.
> > > Specially in the compress buffer size calculation, we notice that
> > > even the libs are not consistent, some of them return int, most of
> > > them unsigned int and others rely on preprocessor calculation.
> > >
> > > Here is an attempt to make it consistent: since we're talking
> > > about buffer sizes, let's go with unsigned types, since negative
> > > sizes don't make sense.
> >
> > Thanks for this! I want to go through this more carefully, but I'm a fan
> > of the clean-up. I'd also like to get Ard's compression refactor landed
> > again, and then do this on top of it.
> >
>
> Isn't this the stuff we want to move into the crypto API?

It is, yes. Guilherme, for background:
https://lore.kernel.org/linux-crypto/20180802215118.17752-1-keescook@xxxxxxxxxxxx/

--
Kees Cook