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From: Bernd Edlinger <bernd.edlinger@hotmail.de>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>,
	Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Oleg Nesterov <oleg@redhat.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Andrei Vagin <avagin@gmail.com>, Ingo Molnar <mingo@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Yuyang Du <duyuyang@gmail.com>,
	David Hildenbrand <david@redhat.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	David Howells <dhowells@redhat.com>,
	James Morris <jamorris@linux.microsoft.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Shakeel Butt <shakeelb@google.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Christian Kellner <christian@kellner.me>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Aleksa Sarai <cyphar@cyphar.com>,
	"Dmitry V. Levin" <ldv@altlinux.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>
Subject: Re: [PATCH v2 4/5] exec: Move exec_mmap right after de_thread in flush_old_exec
Date: Mon, 9 Mar 2020 19:52:38 +0000	[thread overview]
Message-ID: <AM6PR03MB51709D441EE6830DC8CE3090E4FE0@AM6PR03MB5170.eurprd03.prod.outlook.com> (raw)
In-Reply-To: <87tv2xz510.fsf@x220.int.ebiederm.org>



On 3/9/20 8:45 PM, Eric W. Biederman wrote:
> Bernd Edlinger <bernd.edlinger@hotmail.de> writes:
> 
>> On 3/8/20 10:38 PM, Eric W. Biederman wrote:
>>>
>>> This consolidation allows the creation of a mutex to replace
>>> cred_guard_mutex that is not held of possible indefinite userspace
>>
>> can you also reword this "held of" thing here as well?
> 
> Done:
> 
>     exec: Move exec_mmap right after de_thread in flush_old_exec
>     
>     I have read through the code in exec_mmap and I do not see anything
>     that depends on sighand or the sighand lock, or on signals in anyway
>     so this should be safe.
>     
>     This rearrangement of code has two siginficant benefits.  It makes

watch out: sig_i_nificant

>     the determination of passing the point of no return by testing bprm->mm
>     accurate.  All failures prior to that point in flush_old_exec are
>     either truly recoverable or they are fatal.
>     
>     Futher this consolidates all of the possible indefinite waits for

Add some r to "Futher", please?

>     userspace together at the top of flush_old_exec.  The possible wait
>     for a ptracer on PTRACE_EVENT_EXIT, the possible wait for a page fault
>     to be resolved in clear_child_tid, and the possible wait for a page
>     fault in exit_robust_list.
>     
>     This consolidation allows the creation of a mutex to replace
>     cred_guard_mutex that is not held over possible indefinite userspace
>     waits.  Which will allow removing deadlock scenarios from the kernel.
>     
>     Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
>     Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> 
> Eric
> 


  reply	other threads:[~2020-03-09 19:52 UTC|newest]

Thread overview: 202+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-01 11:27 [PATCH] exec: Fix a deadlock in ptrace Bernd Edlinger
2020-03-01 15:13 ` Aleksa Sarai
2020-03-01 15:58   ` Christian Brauner
2020-03-01 17:46     ` Bernd Edlinger
2020-03-01 18:20       ` Christian Brauner
2020-03-01 17:24   ` Bernd Edlinger
2020-03-01 18:21 ` Jann Horn
2020-03-01 18:52   ` Christian Brauner
2020-03-01 19:00     ` Bernd Edlinger
2020-03-01 20:00     ` Jann Horn
2020-03-01 20:34       ` [PATCHv2] " Bernd Edlinger
2020-03-02  6:38         ` Eric W. Biederman
2020-03-02 15:43           ` Bernd Edlinger
2020-03-02 15:57             ` Eric W. Biederman
2020-03-02 16:02               ` Bernd Edlinger
2020-03-02 16:17                 ` Eric W. Biederman
2020-03-02 16:43                   ` Jann Horn
2020-03-02 17:01                     ` Bernd Edlinger
2020-03-02 17:37                       ` Jann Horn
2020-03-02 17:42                         ` christian
2020-03-02 18:08                           ` Jann Horn
2020-03-02 20:10                             ` [PATCHv3] " Bernd Edlinger
2020-03-02 20:28                               ` Bernd Edlinger
2020-03-03 20:13                     ` [PATCHv2] " Eric W. Biederman
2020-03-02 17:13                   ` Bernd Edlinger
2020-03-02 21:49                     ` Eric W. Biederman
2020-03-02 22:00                       ` Bernd Edlinger
2020-03-02 22:18                       ` [PATCHv4] " Bernd Edlinger
2020-03-03  2:26                         ` Kees Cook
2020-03-03  4:54                           ` Bernd Edlinger
2020-03-03  5:29                             ` Kees Cook
2020-03-03  8:08                               ` Bernd Edlinger
2020-03-03  8:34                                 ` Christian Brauner
2020-03-03  8:43                                   ` Christian Brauner
2020-03-04 15:30                                 ` Christian Brauner
2020-03-03  8:58                           ` Christian Brauner
2020-03-03 10:34                             ` Bernd Edlinger
2020-03-03 11:23                               ` Bernd Edlinger
2020-03-03 14:20                                 ` Christian Brauner
2020-03-03 13:02                             ` [PATCHv5] " Bernd Edlinger
2020-03-03 15:18                               ` Eric W. Biederman
2020-03-03 16:48                                 ` Bernd Edlinger
2020-03-03 17:01                                   ` Christian Brauner
2020-03-03 17:20                                     ` Christian Brauner
2020-03-03 20:08                                   ` Eric W. Biederman
2020-03-04 14:37                                     ` Bernd Edlinger
2020-03-04 16:33                                       ` Eric W. Biederman
2020-03-04 21:49                                         ` Bernd Edlinger
2020-03-04 21:56                                         ` [PATCHv6] " Bernd Edlinger
2020-03-05 18:36                                           ` Bernd Edlinger
2020-03-05 21:14                                             ` [PATCH 0/2] Infrastructure to allow fixing exec deadlocks Eric W. Biederman
2020-03-05 21:15                                               ` [PATCH 1/2] exec: Properly mark the point of no return Eric W. Biederman
2020-03-05 22:34                                                 ` Bernd Edlinger
2020-03-06  5:19                                                   ` Eric W. Biederman
2020-03-05 22:56                                                 ` Bernd Edlinger
2020-03-06  5:09                                                   ` Eric W. Biederman
2020-03-06 16:26                                                     ` Bernd Edlinger
2020-03-06 17:16                                                       ` Eric W. Biederman
2020-03-05 21:16                                               ` [PATCH 2/2] exec: Add a exec_update_mutex to replace cred_guard_mutex Eric W. Biederman
2020-03-05 21:51                                                 ` Bernd Edlinger
2020-03-06  5:17                                                   ` Eric W. Biederman
2020-03-06 11:46                                                     ` Bernd Edlinger
2020-03-06 21:18                                                       ` Eric W. Biederman
2020-03-06 19:16                                                     ` Bernd Edlinger
2020-03-06 21:58                                                       ` Eric W. Biederman
2020-03-06 22:29                                                         ` Eric W. Biederman
2020-03-07  1:03                                                           ` Eric W. Biederman
2020-03-08 12:58                                                             ` [PATCH] exec: make de_thread alloc new signal struct earlier Bernd Edlinger
2020-03-08 18:12                                                               ` Eric W. Biederman
2020-03-05 22:31                                               ` [PATCH 0/2] Infrastructure to allow fixing exec deadlocks Bernd Edlinger
2020-03-06  5:06                                                 ` Eric W. Biederman
2020-03-08 21:34                                               ` [PATCH 0/5] " Eric W. Biederman
2020-03-08 21:35                                                 ` [PATCH v2 1/5] exec: Only compute current once in flush_old_exec Eric W. Biederman
2020-03-09 13:56                                                   ` Bernd Edlinger
2020-03-09 17:34                                                     ` Eric W. Biederman
2020-03-09 17:56                                                       ` Bernd Edlinger
2020-03-09 19:27                                                         ` Bernd Edlinger
2020-03-10 20:17                                                   ` Kees Cook
2020-03-10 21:12                                                   ` Christian Brauner
2020-03-08 21:36                                                 ` [PATCH v2 2/5] exec: Factor unshare_sighand out of de_thread and call it separately Eric W. Biederman
2020-03-09 19:28                                                   ` Bernd Edlinger
2020-03-10 20:29                                                   ` Kees Cook
2020-03-10 20:34                                                     ` Bernd Edlinger
2020-03-10 20:57                                                       ` Kees Cook
2020-03-10 21:21                                                   ` Christian Brauner
2020-03-08 21:36                                                 ` [PATCH v2 3/5] exec: Move cleanup of posix timers on exec out of de_thread Eric W. Biederman
2020-03-09 19:30                                                   ` Bernd Edlinger
2020-03-09 19:59                                                   ` Christian Brauner
2020-03-09 20:06                                                     ` Eric W. Biederman
2020-03-09 20:17                                                       ` Christian Brauner
2020-03-09 20:48                                                         ` Eric W. Biederman
2020-03-10  8:55                                                           ` Christian Brauner
2020-03-10 18:52                                                             ` [PATCH] pidfd: Stop taking cred_guard_mutex Eric W. Biederman
2020-03-10 19:15                                                               ` Christian Brauner
2020-03-10 19:16                                                               ` Jann Horn
2020-03-10 19:27                                                                 ` Eric W. Biederman
2020-03-10 20:00                                                                   ` Jann Horn
2020-03-10 20:10                                                                     ` Jann Horn
2020-03-10 20:22                                                                       ` Bernd Edlinger
2020-03-11  6:11                                                                         ` Bernd Edlinger
2020-03-11 14:56                                                                           ` Jann Horn
2020-03-10 20:57                                                                       ` Eric W. Biederman
2020-03-10 21:29                                                                         ` Christian Brauner
2020-03-11 18:49                                                                         ` Kees Cook
2020-03-14  9:12                                                                           ` [PATCH] pidfd: Use new infrastructure to fix deadlocks in execve Bernd Edlinger
2020-03-10 20:16                                                           ` [PATCH v2 3/5] exec: Move cleanup of posix timers on exec out of de_thread Kees Cook
2020-03-10 20:31                                                   ` Kees Cook
2020-03-10 20:57                                                   ` Jann Horn
2020-03-10 21:05                                                     ` Eric W. Biederman
2020-03-10 21:22                                                   ` Christian Brauner
2020-03-08 21:38                                                 ` [PATCH v2 4/5] exec: Move exec_mmap right after de_thread in flush_old_exec Eric W. Biederman
2020-03-09 19:34                                                   ` Bernd Edlinger
2020-03-09 19:45                                                     ` Eric W. Biederman
2020-03-09 19:52                                                       ` Bernd Edlinger [this message]
2020-03-09 19:58                                                         ` Eric W. Biederman
2020-03-09 20:03                                                           ` Bernd Edlinger
2020-03-09 20:35                                                             ` Eric W. Biederman
2020-03-10 20:44                                                   ` Kees Cook
2020-03-10 21:20                                                     ` Eric W. Biederman
2020-03-10 20:47                                                   ` Kees Cook
2020-03-10 21:09                                                     ` Eric W. Biederman
2020-03-08 21:38                                                 ` [PATCH v2 5/5] exec: Add a exec_update_mutex to replace cred_guard_mutex Eric W. Biederman
2020-03-09 13:45                                                   ` Bernd Edlinger
2020-03-09 17:40                                                     ` Eric W. Biederman
2020-03-09 18:01                                                       ` Bernd Edlinger
2020-03-09 18:10                                                         ` Eric W. Biederman
2020-03-09 18:24                                                           ` Eric W. Biederman
2020-03-09 18:36                                                             ` Eric W. Biederman
2020-03-09 18:47                                                               ` Bernd Edlinger
2020-03-09 19:02                                                                 ` Eric W. Biederman
2020-03-09 19:24                                                                   ` Bernd Edlinger
2020-03-09 19:35                                                                     ` Eric W. Biederman
2020-03-09 19:39                                                                     ` Eric W. Biederman
2020-03-10 13:43                                                                       ` [PATCH 0/4] Use new infrastructure to fix deadlocks in execve Bernd Edlinger
2020-03-10 15:35                                                                         ` Eric W. Biederman
2020-03-10 17:44                                                                           ` [PATCH 0/4] Use new infrastructure in more simple cases Bernd Edlinger
2020-03-10 17:45                                                                           ` [PATCH 1/4] kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve Bernd Edlinger
2020-03-10 19:01                                                                             ` Eric W. Biederman
2020-03-10 19:42                                                                               ` Bernd Edlinger
2020-03-10 17:45                                                                           ` [PATCH 2/4] proc: " Bernd Edlinger
2020-03-11 18:59                                                                             ` Kees Cook
2020-03-11 19:10                                                                             ` Kees Cook
2020-03-11 19:38                                                                               ` Bernd Edlinger
2020-03-10 17:45                                                                           ` [PATCH 3/4] proc: io_accounting: " Bernd Edlinger
2020-03-10 19:06                                                                             ` Eric W. Biederman
     [not found]                                                                               ` <AM6PR03MB5170A29F8D885147F1A3981EE4FF0@AM6PR03MB5170.eurprd03.prod.outlook.com>
2020-03-10 21:25                                                                                 ` Eric W. Biederman
2020-03-11 19:08                                                                             ` Kees Cook
2020-03-11 19:48                                                                               ` Bernd Edlinger
2020-03-11 19:48                                                                               ` Eric W. Biederman
2020-03-10 17:45                                                                           ` [PATCH 4/4] perf: " Bernd Edlinger
2020-03-10 13:43                                                                       ` [PATCH 1/4] exec: Fix a deadlock in ptrace Bernd Edlinger
2020-03-10 15:13                                                                         ` Eric W. Biederman
2020-03-10 15:17                                                                           ` Bernd Edlinger
2020-03-10 21:00                                                                         ` Kees Cook
2020-03-10 13:44                                                                       ` [PATCH 2/4] selftests/ptrace: add test cases for dead-locks Bernd Edlinger
2020-03-10 21:36                                                                         ` Kees Cook
2020-03-10 22:41                                                                         ` Dmitry V. Levin
2020-03-10 13:44                                                                       ` [PATCH 3/4] mm: docs: Fix a comment in process_vm_rw_core Bernd Edlinger
2020-03-11 18:53                                                                         ` Kees Cook
2020-03-10 13:44                                                                       ` [PATCH 4/4] kernel: doc: remove outdated comment cred.c Bernd Edlinger
2020-03-11 18:54                                                                         ` Kees Cook
2020-03-09 19:33                                                                   ` [PATCH v2 5/5] exec: Add a exec_update_mutex to replace cred_guard_mutex Dmitry V. Levin
2020-03-09 19:42                                                                     ` Eric W. Biederman
2020-03-10 20:55                                                                   ` Kees Cook
2020-03-10 21:02                                                                     ` Eric W. Biederman
2020-03-10 21:21                                                   ` Jann Horn
2020-03-10 21:30                                                     ` Eric W. Biederman
2020-03-10 23:21                                                       ` Jann Horn
2020-03-11  0:15                                                         ` Eric W. Biederman
2020-03-11  6:33                                                           ` Bernd Edlinger
2020-03-11 13:18                                                   ` Qian Cai
2020-03-12 10:27                                                   ` Kirill Tkhai
2020-03-12 12:24                                                     ` Eric W. Biederman
2020-03-12 13:45                                                       ` Kirill Tkhai
2020-03-12 14:38                                                         ` Eric W. Biederman
2020-03-12 15:23                                                           ` Kirill Tkhai
2020-03-13  1:05                                                           ` Bernd Edlinger
2020-03-13  9:13                                                             ` Kirill Tkhai
2020-03-14  9:11                                                               ` [PATCH v3 " Bernd Edlinger
2020-03-17  8:56                                                                 ` Kirill Tkhai
2020-03-17 21:53                                                                   ` Bernd Edlinger
2020-03-18 12:22                                                                     ` Kirill Tkhai
2020-03-18 20:06                                                                       ` Bernd Edlinger
2020-03-19  7:13                                                                         ` Kirill Tkhai
2020-03-19  7:19                                                                           ` Bernd Edlinger
2020-03-19  9:11                                                                           ` [PATCH v4 3/5] " Bernd Edlinger
2020-03-19  9:13                                                                             ` Bernd Edlinger
2020-03-19  9:19                                                                               ` Greg Kroah-Hartman
2020-03-19  9:20                                                                                 ` Bernd Edlinger
2020-03-21 22:53                                                                                 ` Bernd Edlinger
2020-03-14  9:12                                                               ` [PATCH 0/2] exec: Fix dead-lock in de_thread with ptrace_attach Bernd Edlinger
2020-03-14  9:12                                                               ` [PATCH 1/2] " Bernd Edlinger
2020-03-14  9:13                                                               ` [PATCH 2/2] doc: Update documentation of ->exec_*_mutex Bernd Edlinger
2020-03-14  9:57                                                               ` [PATCH v2 5/5] exec: Add a exec_update_mutex to replace cred_guard_mutex Bernd Edlinger
2020-03-14 10:02                                                                 ` Bernd Edlinger
2020-03-17  8:58                                                                   ` Kirill Tkhai
2020-03-09 13:58                                                 ` [PATCH 0/5] Infrastructure to allow fixing exec deadlocks Bernd Edlinger
2020-03-03 16:50                                 ` [PATCHv5] exec: Fix a deadlock in ptrace Christian Brauner
2020-03-02 12:28         ` [PATCHv2] " Oleg Nesterov
2020-03-02 15:56           ` Bernd Edlinger
2020-03-02  7:47       ` [PATCH] " Christian Brauner
2020-03-02  7:48         ` Christian Brauner

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