Re: [PATCH] ucounts: Fix UCOUNT_RLIMIT_SIGPENDING counter leak

Alexey Gladkov
2021-07-08T11:00:22Z

On Wed, Jul 07, 2021 at 10:23:35AM -0700, Linus Torvalds wrote:
> On Wed, Jul 7, 2021 at 9:50 AM Alexey Gladkov <legion@kernel.org> wrote:
> >
> > > + dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING, 1);
> > > + fallthrough;
> > > + case LONG_MAX:
> >
> > I think that the counter should be decreased in this case too.
> > inc_rlimit_ucounts() increments the counter in all parent userns. If we
> > don't decrease the counter then the parent userns will have a counter
> > leak.
>
> Ack. So basically that patch, but move the dec_rlimit_ucounts() into
> the LONG_MAX case?

Yep.

> Would you mind making a real patch with a commit message, and trying
> whatever test-case you had for that KASAN use-after-free report?

Sure. I will.

--
Rgrds, legion