From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oren Laadan Subject: Re: [PATCH RFC] nsproxy: strengthen the comment above copy_namespaces Date: Mon, 14 Jun 2010 22:54:13 -0400 Message-ID: <4C16EB55.1090101@cs.columbia.edu> References: <20100430183638.GA29240@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100430183638.GA29240-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Serge E. Hallyn" Cc: Linux Containers , "Eric W. Biederman" List-Id: containers.vger.kernel.org Serge - Is this intended for linux-cr ? Sounds like it should go (or already?) upstream. Oren. On 04/30/2010 02:36 PM, Serge E. Hallyn wrote: > copy_namespaces() cannot be used on a live task. There are two > reasons - it can be used to assign another task's nsproxy, which > is not legal (for a live task). And, it does not use > rcu_assign_pointer, so even when we're being extra-clever it is > unsafe. > > Signed-off-by: Serge Hallyn > --- > kernel/nsproxy.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c > index f74e6c0..67d8f2b 100644 > --- a/kernel/nsproxy.c > +++ b/kernel/nsproxy.c > @@ -115,6 +115,9 @@ out_ns: > /* > * called from clone. This now handles copy for nsproxy and all > * namespaces therein. > + * Note this should only be used in fork. Specifically, tsk should > + * not yet be a live task. See the the unshare code for how to handle > + * that. > */ > int copy_namespaces(unsigned long flags, struct task_struct *tsk) > {