Date:   Wed, 25 Mar 2020 16:33:58 +0100
From:   Bernd Edlinger <bernd.edlinger@...mail.de>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Kees Cook <keescook@...omium.org>,
        Jann Horn <jannh@...gle.com>, Jonathan Corbet <corbet@....net>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Oleg Nesterov <oleg@...hat.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Andrei Vagin <avagin@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Yuyang Du <duyuyang@...il.com>,
        David Hildenbrand <david@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Anshuman Khandual <anshuman.khandual@....com>,
        David Howells <dhowells@...hat.com>,
        James Morris <jamorris@...ux.microsoft.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Christian Kellner <christian@...lner.me>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Aleksa Sarai <cyphar@...har.com>,
        "Dmitry V. Levin" <ldv@...linux.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>
Subject: Re: [PATCH v6 00/16] Infrastructure to allow fixing exec deadlocks

On 3/25/20 4:10 PM, Eric W. Biederman wrote:
> Bernd Edlinger <bernd.edlinger@...mail.de> writes:
> 
>> This is an infrastructure change that makes way for fixing this issue.
>> Each patch was already posted previously so this is just a cleanup of
>> the original mailing list thread(s) which got out of control by now.
>>
>> Everything started here:
>> https://lore.kernel.org/lkml/AM6PR03MB5170B06F3A2B75EFB98D071AE4E60@AM6PR03MB5170.eurprd03.prod.outlook.com/
>>
>> I added reviewed-by tags from the mailing list threads, except when
>> withdrawn.
>>
>> It took a lot longer than expected to collect everything from the
>> mailinglist threads, since several commit messages have been infected
>> with typos, and they got fixed without a new patch version.
>>
>> - Correct the point of no return.
>> - Add two new mutexes to replace cred_guard_mutex.
>> - Fix each use of cred_guard_mutex.
>> - Update documentation.
>> - Add a test case.
>>
>> Bernd Edlinger (11):
>>   exec: Fix a deadlock in strace
>>   selftests/ptrace: add test cases for dead-locks
>>   mm: docs: Fix a comment in process_vm_rw_core
>>   kernel: doc: remove outdated comment cred.c
>>   kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve
>>   proc: Use new infrastructure to fix deadlocks in execve
>>   proc: io_accounting: Use new infrastructure to fix deadlocks in execve
>>   perf: Use new infrastructure to fix deadlocks in execve
>>   pidfd: Use new infrastructure to fix deadlocks in execve
>>   exec: Fix dead-lock in de_thread with ptrace_attach
>>   doc: Update documentation of ->exec_*_mutex
>>
>> Eric W. Biederman (5):
>>   exec: Only compute current once in flush_old_exec
>>   exec: Factor unshare_sighand out of de_thread and call it separately
>>   exec: Move cleanup of posix timers on exec out of de_thread
>>   exec: Move exec_mmap right after de_thread in flush_old_exec
>>   exec: Add exec_update_mutex to replace cred_guard_mutex
>>
>>  Documentation/security/credentials.rst    |  29 +++++--
>>  fs/exec.c                                 | 122 ++++++++++++++++++++++--------
>>  fs/proc/base.c                            |  23 +++---
>>  include/linux/binfmts.h                   |   8 +-
>>  include/linux/sched/signal.h              |  17 ++++-
>>  init/init_task.c                          |   3 +-
>>  kernel/cred.c                             |   4 +-
>>  kernel/events/core.c                      |  12 +--
>>  kernel/fork.c                             |   7 +-
>>  kernel/kcmp.c                             |   8 +-
>>  kernel/pid.c                              |   4 +-
>>  kernel/ptrace.c                           |  20 ++++-
>>  kernel/seccomp.c                          |  15 ++--
>>  mm/process_vm_access.c                    |   2 +-
>>  tools/testing/selftests/ptrace/Makefile   |   4 +-
>>  tools/testing/selftests/ptrace/vmaccess.c |  86 +++++++++++++++++++++
>>  16 files changed, 278 insertions(+), 86 deletions(-)
>>  create mode 100644 tools/testing/selftests/ptrace/vmaccess.c
> 
> Two small nits.
> 
> - You reposted my patches with adding your signed-off-by
> - You reposted my patches and did not include a "From:"
>   in the body so "git am" listed you as the author.
> 
> I have fixed those up and will be merging this code to linux-next,
> unless you object.
> 

Thanks, I have not expected that a From: which names a different domain
than hotmail.de would be forwarded by the SMTP servers I have to use.
Actually I was not even aware of the problem at all.

The Patch "exec: Add exec_update_mutex to replace cred_guard_mutex"
was initially reviewed-by: bernd.edlinger@...mail.de but it turned out
to be faulty, so I update your patch faithfully, and did a small change
to fix the patch, therefore it is actually 99% your and 1% my patch,
therefore I figured I should be in a signed-off-by: together with you.
BTW: I saw a Reviewed-by: Kirill Tkhai <ktkhai@...tuozzo.com> on the mailing list,
you should add that as well.


Thanks
Bernd.

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