| From: |
| ebiederm-AT-xmission.com |
| To: |
| <linux-kernel-AT-vger.kernel.org> |
| Subject: |
| [PATCH 0/3] signal: requeuing undeliverable signals |
| Date: |
| Mon, 15 Nov 2021 23:29:11 -0600 |
| Message-ID: |
| <87bl2kekig.fsf_-_@email.froward.int.ebiederm.org> |
| Cc: |
| Kyle Huey <me-AT-kylehuey.com>, Jens Axboe <axboe-AT-kernel.dk>, Peter Zijlstra <peterz-AT-infradead.org>, Marco Elver <elver-AT-google.com>, Oleg Nesterov <oleg-AT-redhat.com>, Thomas Gleixner <tglx-AT-linutronix.de>, Peter Collingbourne <pcc-AT-google.com>, Alexey Gladkov <legion-AT-kernel.org>, "Robert O'Callahan" <rocallahan-AT-gmail.com>, Marko Mäkelä <marko.makela-AT-mariadb.com>, <linux-api-AT-vger.kernel.org>, Al Viro <viro-AT-ZenIV.linux.org.uk>, Linus Torvalds <torvalds-AT-linux-foundation.org>, Kees Cook <keescook-AT-chromium.org> |
| Archive-link: |
| Article |
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@kyl...
[2] https://lkml.kernel.org/r/CAP045ApAX725ZfujaK-jJNkfCo5s+o...
Eric
