From: ebiederm@xmission.com (Eric W. Biederman)
To: <linux-kernel@vger.kernel.org>
Cc: "Kyle Huey" <me@kylehuey.com>, "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@vger.kernel.org, "Al Viro" <viro@ZenIV.linux.org.uk>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Kees Cook" <keescook@chromium.org>
Subject: [PATCH 0/3] signal: requeuing undeliverable signals
Date: Mon, 15 Nov 2021 23:29:11 -0600 [thread overview]
Message-ID: <87bl2kekig.fsf_-_@email.froward.int.ebiederm.org> (raw)
In-Reply-To: <CAP045AqsstnxfTyXhhCGDSucqGN7BTtfHJ5s6ZxUQC5K-JU56A@mail.gmail.com> (Kyle Huey's message of "Mon, 8 Nov 2021 15:58:21 -0800")
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.
Eric W. Biederman (3):
signal: In get_signal test for signal_group_exit every time through the loop
signal: Requeue signals in the appropriate queue
signal: Requeue ptrace signals
fs/signalfd.c | 5 +++--
include/linux/sched/signal.h | 7 ++++---
kernel/signal.c | 44 ++++++++++++++++++++++++++------------------
3 files changed, 33 insertions(+), 23 deletions(-)
[1] https://lkml.kernel.org/r/20211101034147.6203-1-khuey@kylehuey.com
[2] https://lkml.kernel.org/r/CAP045ApAX725ZfujaK-jJNkfCo5s+oVFpBvNfPJk+DKY8K7d=Q@mail.gmail.com
Eric
next prev parent reply other threads:[~2021-11-16 5:31 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 ` Eric W. Biederman [this message]
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
2021-11-18 6:12 ` Marko Mäkelä
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