From: Florian Weimer <fweimer@redhat.com>
To: Zack Weinberg <zackw@panix.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carlos O'Donell <carlos@redhat.com>,
Shawn Landden <shawn@git.icu>,
GNU C Library <libc-alpha@sourceware.org>,
linux-api@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Deepa Dinamani <deepa.kernel@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Keith Packard <keithp@keithp.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC v2 PATCH] futex: extend set_robust_list to allow 2 locking ABIs at the same time.
Date: Wed, 06 Nov 2019 15:04:17 +0100 [thread overview]
Message-ID: <87a799nlsu.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <CAKCAbMjYBpTjwyMJkkENps09o4KFoQAb_KOKp4g0BtWUXjYAzQ@mail.gmail.com> (Zack Weinberg's message of "Wed, 6 Nov 2019 09:00:51 -0500")
* Zack Weinberg:
> On Tue, Nov 5, 2019 at 9:28 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>>
>> The real issue is that the robust list could be circular by incident or
>> malice and there is no way for the kernel to figure that out. That would
>> prevent the task from exiting and make it iterate over the list until
>> doomsday, i.e. a nice unpriviledged DoS.
>
> Why can't the kernel use the standard tortoise-and-hare algorithm for
> detecting circular linked lists here?
It's not guaranteed to terminate if the list is in shared memory.
Thanks,
Florian
next prev parent reply other threads:[~2019-11-06 14:04 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-04 0:29 [RFC v2 PATCH] futex: extend set_robust_list to allow 2 locking ABIs at the same time Shawn Landden
2019-11-04 0:51 ` Shawn Landden
2019-11-04 15:37 ` Thomas Gleixner
2019-11-05 0:10 ` Thomas Gleixner
2019-11-05 9:48 ` Florian Weimer
2019-11-05 9:59 ` Thomas Gleixner
2019-11-05 10:06 ` Florian Weimer
2019-11-05 11:56 ` Thomas Gleixner
2019-11-05 14:10 ` Carlos O'Donell
2019-11-05 14:27 ` Florian Weimer
2019-11-05 14:53 ` Thomas Gleixner
2019-11-05 14:27 ` Thomas Gleixner
2019-11-05 14:33 ` Florian Weimer
2019-11-05 14:48 ` Thomas Gleixner
2019-11-06 14:00 ` Zack Weinberg
2019-11-06 14:04 ` Florian Weimer [this message]
2019-11-05 15:27 ` handle_exit_race && PF_EXITING Oleg Nesterov
2019-11-05 17:28 ` Thomas Gleixner
2019-11-05 17:59 ` Thomas Gleixner
2019-11-05 18:56 ` Thomas Gleixner
2019-11-05 19:19 ` Thomas Gleixner
2019-11-06 8:55 ` Oleg Nesterov
2019-11-06 9:53 ` Thomas Gleixner
2019-11-06 10:35 ` Oleg Nesterov
2019-11-06 11:07 ` Thomas Gleixner
2019-11-06 12:11 ` Oleg Nesterov
2019-11-06 13:38 ` Thomas Gleixner
2019-11-06 17:42 ` Thomas Gleixner
2019-11-07 15:51 ` Oleg Nesterov
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