From: David Howells <dhowells@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Oleg Nesterov <oleg@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: dhowells@redhat.com, LKML <linux-kernel@vger.kernel.org>,
Dipankar Sarma <dipankar@in.ibm.com>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Al Viro <viro@zeniv.linux.org.uk>,
James Morris <jmorris@namei.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-security-module@vger.kernel.org
Subject: Re: [patch 1/9] sys: Fix missing rcu protection for __task_cred() access
Date: Fri, 11 Dec 2009 13:45:20 +0000 [thread overview]
Message-ID: <13183.1260539120@redhat.com> (raw)
In-Reply-To: <alpine.LFD.2.00.0912101542200.3089@localhost.localdomain>
Thomas Gleixner <tglx@linutronix.de> wrote:
> > > Or are there updates that are carried out without write-holding
> > > tasklist_lock that I am missing?
> >
> > Yes, commit_creds() is called lockless.
>
> Right, and that's what the problem is. commit_creds(), which rcu frees
> the old creds, does not take tasklist lock write lock.
commit_creds() does not need to hold a write lock, because it is implicitly
write-locked by only being permitted to run in the thread to which it is
committing.
I don't think commit_creds() needs to take the RCU read lock as no-one else
can alter/delete the creds it is dealing with.
David
next prev parent reply other threads:[~2009-12-11 13:46 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-10 0:52 [patch 0/9] Fix various __task_cred related invalid RCU assumptions Thomas Gleixner
2009-12-10 0:52 ` [patch 1/9] sys: Fix missing rcu protection for __task_cred() access Thomas Gleixner
2009-12-10 1:25 ` Paul E. McKenney
2009-12-10 2:29 ` Tetsuo Handa
2009-12-10 2:43 ` Paul E. McKenney
2009-12-10 14:29 ` Oleg Nesterov
2009-12-10 14:44 ` Thomas Gleixner
2009-12-11 13:45 ` David Howells [this message]
2009-12-11 13:52 ` Thomas Gleixner
2009-12-10 14:20 ` Oleg Nesterov
2009-12-10 14:38 ` Thomas Gleixner
2009-12-10 15:08 ` [patch 1/9] sys: Fix missing rcu protection for __task_cred()access Tetsuo Handa
2009-12-10 21:17 ` Thomas Gleixner
2009-12-11 3:25 ` Tetsuo Handa
2010-02-08 12:30 ` [PATCH] Update comment on find_task_by_pid_ns Tetsuo Handa
2010-02-08 13:21 ` Oleg Nesterov
2010-02-08 17:07 ` Thomas Gleixner
2010-02-08 17:16 ` Oleg Nesterov
2010-02-08 21:42 ` Tetsuo Handa
2010-02-09 22:08 ` Andrew Morton
2010-02-10 16:30 ` Serge E. Hallyn
2010-02-10 17:57 ` Andrew Morton
2010-02-10 18:39 ` Thomas Gleixner
2010-02-10 20:18 ` Serge E. Hallyn
2010-02-10 20:30 ` Paul E. McKenney
2010-02-11 1:21 ` Tetsuo Handa
2010-02-11 12:04 ` [PATCH] sys: Fix missing rcu protection for sys_getpriority Tetsuo Handa
2010-02-12 14:22 ` Serge E. Hallyn
2009-12-10 22:09 ` [tip:core/urgent] sys: Fix missing rcu protection for __task_cred() access tip-bot for Thomas Gleixner
2009-12-10 0:52 ` [patch 2/9] fs: Add missing rcu protection for __task_cred() in sys_ioprio_get Thomas Gleixner
2009-12-10 0:53 ` [patch 3/9] proc: Add missing rcu protection for __task_cred() in task_sig() Thomas Gleixner
2009-12-10 0:53 ` [patch 4/9] oom: Add missing rcu protection of __task_cred() in dump_tasks Thomas Gleixner
2009-12-10 0:53 ` Thomas Gleixner
2009-12-10 1:57 ` KOSAKI Motohiro
2009-12-10 1:57 ` KOSAKI Motohiro
2009-12-10 0:53 ` [patch 5/9] security: Use get_task_cred() in keyctl_session_to_parent() Thomas Gleixner
2009-12-10 2:45 ` Paul E. McKenney
2009-12-10 0:53 ` [patch 6/9] signal: Fix racy access to __task_cred in kill_pid_info_as_uid() Thomas Gleixner
2009-12-10 15:11 ` Oleg Nesterov
2009-12-10 22:09 ` [tip:core/urgent] " tip-bot for Thomas Gleixner
2009-12-10 0:53 ` [patch 7/9] signals: Fix more rcu assumptions Thomas Gleixner
2009-12-10 14:34 ` Oleg Nesterov
2009-12-10 14:45 ` Thomas Gleixner
2009-12-11 13:59 ` David Howells
2009-12-10 22:09 ` [tip:core/urgent] " tip-bot for Thomas Gleixner
2009-12-10 0:53 ` [patch 8/9] Documentation: Fix invalid " Thomas Gleixner
2009-12-10 23:55 ` Vegard Nossum
2009-12-11 21:28 ` Arnd Bergmann
2009-12-11 22:01 ` Paul E. McKenney
2009-12-10 0:53 ` [patch 9/9] security: Fix invalid rcu assumptions in comments Thomas Gleixner
2009-12-10 2:28 ` [patch 0/9] Fix various __task_cred related invalid RCU assumptions Paul E. McKenney
2009-12-10 3:15 ` Linus Torvalds
2009-12-10 5:13 ` Peter Zijlstra
2009-12-10 5:34 ` Paul E. McKenney
2009-12-13 18:56 ` Peter Zijlstra
2009-12-14 1:53 ` Paul E. McKenney
2009-12-14 10:17 ` Peter Zijlstra
2009-12-14 14:16 ` Paul E. McKenney
2009-12-14 14:30 ` Peter Zijlstra
2009-12-15 1:23 ` Paul E. McKenney
2009-12-11 13:39 ` David Howells
2009-12-11 16:35 ` Paul E. McKenney
2009-12-11 13:41 ` [patch 1/9] sys: Fix missing rcu protection for __task_cred() access David Howells
2009-12-11 13:46 ` [patch 2/9] fs: Add missing rcu protection for __task_cred() in sys_ioprio_get David Howells
2009-12-11 13:46 ` [patch 3/9] proc: Add missing rcu protection for __task_cred() in task_sig() David Howells
2009-12-11 13:49 ` [patch 4/9] oom: Add missing rcu protection of __task_cred() in dump_tasks David Howells
2009-12-11 13:49 ` David Howells
2009-12-11 13:52 ` Thomas Gleixner
2009-12-11 13:52 ` Thomas Gleixner
2009-12-11 13:52 ` [patch 5/9] security: Use get_task_cred() in keyctl_session_to_parent() David Howells
2009-12-11 13:53 ` [patch 6/9] signal: Fix racy access to __task_cred in kill_pid_info_as_uid() David Howells
2009-12-11 14:00 ` [patch 8/9] Documentation: Fix invalid rcu assumptions David Howells
2009-12-11 16:07 ` Linus Torvalds
2009-12-11 16:37 ` Paul E. McKenney
2009-12-11 18:08 ` Thomas Gleixner
2009-12-11 14:01 ` [patch 9/9] security: Fix invalid rcu assumptions in comments David Howells
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