linux-kernel - Re: [BUG] ptraced process waiting on syscall may return kernel internal errnos

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 14 Jun 2007 09:18:49 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Roland McGrath <roland@...hat.com>
Cc:	Oleg Nesterov <oleg@...sign.ru>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Satoru Takeuchi <takeuchi_satoru@...fujitsu.com>
Subject: Re: [BUG] ptraced process waiting on syscall may return kernel
	internal errnos

On Wed, 2007-06-13 at 16:01 -0700, Roland McGrath wrote:
> 
> > What about something like:
> > 
> >                       do {
> >                               rm_from_queue_full(&mask, &t->pending);
> > -                             recalc_sigpending_and_wake(t);
> >                               t = next_thread(t);
> >                       } while (t != current);
> > +                     recalc_sigpending();
> 
> There is no need for the +, just the -.  The calling thread is the one
> where know there is certainly no perturbation of behavior due to leaving
> TIF_SIGPENDING set rather than clearing it.  It's just going to exit the
> syscall and deal with signal state properly on the way out either way.
> Doing recalc_sigpending is an unnecessary optimization of the corner case.

Fair enough. I'll cook a patch for that one when I'm at work.

> > So at the end of the day, easier to test it inside dequeue_signal().
> 
> Before completely revamping the whole set of entrypoints to be saner all
> around, yes.

btw, another interesting grep is to see how tweak TIF_SIGPENDING by
hand ... there's some scary bits in the tty code too...

Ben.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/