Re: [PATCH] kernel/time: Add max_time_namespaces ucount

[Vincenzo Frascino <vincenzo.frascino@arm.com>]

On 4/7/20 9:22 AM, Michael Kerrisk (man-pages) wrote:
> On Tue, 7 Apr 2020 at 05:31, Andrei Vagin <avagin@gmail.com> wrote:
>>
>> On Mon, Apr 06, 2020 at 06:13:42PM +0100, Dmitry Safonov via Containers wrote:
>>> Introduce missing time namespaces limit per-userns.
>>> Michael noticed that userns limit for number of time namespaces is
>>> missing.
>>>
>>> Furthermore, time namespace introduced UCOUNT_TIME_NAMESPACES, but
>>> didn't introduce an array member in user_table[]. It would make array's
>>> initialisation OOB write, but by luck the user_table array has
>>> an excessive empty member (all accesses to the array are limited with
>>> UCOUNT_COUNTS - so it silently reuses the last free member.
>>>
>>> Fixes user-visible regression: max_inotify_instances by reason of the
>>> missing UCOUNT_ENTRY() has limited max number of namespaces instead of
>>> the number of inotify instances.
>>>
>>> Fixes: 769071ac9f20 ("ns: Introduce Time Namespace")
>>> Cc: Adrian Reber <adrian@lisas.de>
>>> Cc: Andrey Vagin <avagin@openvz.org>
>>> Cc: Christian Brauner <christian.brauner@ubuntu.com>
>>> Cc: Eric W. Biederman <ebiederm@xmission.com>
>>> Cc: Ingo Molnar <mingo@redhat.com>
>>> Cc: Thomas Gleixner <tglx@linutronix.de>
>>> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
>>> Cc: Containers <containers@lists.linux-foundation.org>
>>> Cc: Linux API <linux-api@vger.kernel.org>
>>> Cc: stable@kernel.org # v5.6+
>>> Reported-by: Michael Kerrisk (man-pages) <mtk.manpages@gmail.com>
>>
>> Acked-by: Andrei Vagin <avagin@gmail.com>
> 
> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
> 
> 
> 

Acked-by: Vincenzo Frascino <vincenzo.frascino@arm.com>

-- 
Regards,
Vincenzo