From: ebiederm@xmission.com (Eric W. Biederman)
To: Kyle Huey <me@kylehuey.com>
Cc: "open list" <linux-kernel@vger.kernel.org>,
"Jens Axboe" <axboe@kernel.dk>,
"Peter Zijlstra" <peterz@infradead.org>,
"Marco Elver" <elver@google.com>,
"Oleg Nesterov" <oleg@redhat.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Peter Collingbourne" <pcc@google.com>,
"Alexey Gladkov" <legion@kernel.org>,
"Robert O'Callahan" <rocallahan@gmail.com>,
"Marko Mäkelä" <marko.makela@mariadb.com>,
"Linux API" <linux-api@vger.kernel.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Kees Cook" <keescook@chromium.org>
Subject: Re: [PATCH 0/3] signal: requeuing undeliverable signals
Date: Wed, 17 Nov 2021 10:51:03 -0600 [thread overview]
Message-ID: <87y25m9154.fsf@email.froward.int.ebiederm.org> (raw)
In-Reply-To: <CAP045AqSKv8hAz79ntbj6ZoGiO-v7M0UBuQF2hwJdXqqL7oxWA@mail.gmail.com> (Kyle Huey's message of "Wed, 17 Nov 2021 08:24:28 -0800")
Kyle Huey <me@kylehuey.com> writes:
> On Mon, Nov 15, 2021 at 9:31 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>>
>> Kyle Huey recently reported[1] that rr gets confused if SIGKILL prevents
>> ptrace_signal from delivering a signal, as the kernel setups up a signal
>> frame for a signal that rr did not have a chance to observe with ptrace.
>>
>> In looking into it I found a couple of bugs and a quality of
>> implementation issue.
>>
>> - The test for signal_group_exit should be inside the for loop in get_signal.
>> - Signals should be requeued on the same queue they were dequeued from.
>> - When a fatal signal is pending ptrace_signal should not return another
>> signal for delivery.
>>
>> Kyle Huey has verified[2] an earlier version of this change.
>>
>> I have reworked things one more time to completely fix the issues
>> raised, and to keep the code maintainable long term.
>>
>> I have smoke tested this code and combined with a careful review I
>> expect this code to work fine. Kyle if you can double check that
>> my last round of changes still works for rr I would appreciate it.
>
> This still fixes the race we reported.
>
> Tested-by: Kyle Huey <khuey@kylehuey.com>
Thank you very much for retesting.
Eric
next prev parent reply other threads:[~2021-11-17 16:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-01 3:41 [PATCH] signal: SIGKILL can cause signal effects to appear at PTRACE_EVENT_EXIT without tracer notification Kyle Huey
2021-11-01 3:41 ` [PATCH 1/2] signal: factor out SIGKILL generation in get_signal Kyle Huey
2021-11-01 3:41 ` [PATCH 2/2] signal: after notifying a ptracer of a signal, recheck for pending SIGKILLs Kyle Huey
2021-11-02 14:08 ` [PATCH] signal: SIGKILL can cause signal effects to appear at PTRACE_EVENT_EXIT without tracer notification Eric W. Biederman
2021-11-02 16:01 ` Kyle Huey
2021-11-02 18:06 ` Eric W. Biederman
2021-11-02 19:09 ` Kyle Huey
2021-11-08 23:58 ` Kyle Huey
2021-11-14 17:19 ` Eric W. Biederman
2021-11-16 5:29 ` [PATCH 0/3] signal: requeuing undeliverable signals Eric W. Biederman
2021-11-16 5:32 ` [PATCH 1/3] signal: In get_signal test for signal_group_exit every time through the loop Eric W. Biederman
2021-11-16 18:23 ` Kees Cook
2021-11-17 16:31 ` Eric W. Biederman
2021-11-16 5:33 ` [PATCH 2/3] signal: Requeue signals in the appropriate queue Eric W. Biederman
2021-11-16 18:30 ` Kees Cook
2021-11-17 16:42 ` Eric W. Biederman
2021-11-16 5:34 ` [PATCH 3/3] signal: Requeue ptrace signals Eric W. Biederman
2021-11-16 18:31 ` Kees Cook
2021-11-17 16:44 ` Eric W. Biederman
2021-11-17 16:24 ` [PATCH 0/3] signal: requeuing undeliverable signals Kyle Huey
2021-11-17 16:51 ` Eric W. Biederman [this message]
2021-11-18 6:12 ` Marko Mäkelä
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