[3.13.y-ckt stable] Patch "exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt15.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From a3ca3367fe19da283a1c50342c486f2106995089 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg at redhat.com>
Date: Wed, 10 Dec 2014 15:55:25 -0800
Subject: exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is
 exiting

commit 24c037ebf5723d4d9ab0996433cee4f96c292a4d upstream.

alloc_pid() does get_pid_ns() beforehand but forgets to put_pid_ns() if it
fails because disable_pid_allocation() was called by the exiting
child_reaper.

We could simply move get_pid_ns() down to successful return, but this fix
tries to be as trivial as possible.

Signed-off-by: Oleg Nesterov <oleg at redhat.com>
Reviewed-by: "Eric W. Biederman" <ebiederm at xmission.com>
Cc: Aaron Tomlin <atomlin at redhat.com>
Cc: Pavel Emelyanov <xemul at parallels.com>
Cc: Serge Hallyn <serge.hallyn at ubuntu.com>
Cc: Sterling Alexander <stalexan at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 kernel/pid.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/pid.c b/kernel/pid.c
index 9b9a266..82430c8 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -341,6 +341,8 @@ out:

 out_unlock:
 	spin_unlock_irq(&pidmap_lock);
+	put_pid_ns(ns);
+
 out_free:
 	while (++i <= ns->level)
 		free_pidmap(pid->numbers + i);
--
1.9.1