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[3.11.y.z,extended,stable] Patch "pid_namespace: pidns_get() should check task_active_pid_ns() != NULL" has been added to staging queue

Message ID 1398072726-17021-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques April 21, 2014, 9:32 a.m. UTC
This is a note to let you know that I have just added a patch titled

    pid_namespace: pidns_get() should check task_active_pid_ns() != NULL

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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From a9acbb32982cc5c93bb646bb9135946adee347e3 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Wed, 2 Apr 2014 17:45:05 +0200
Subject: pid_namespace: pidns_get() should check task_active_pid_ns() != NULL

commit d23082257d83e4bc89727d5aedee197e907999d2 upstream.

pidns_get()->get_pid_ns() can hit ns == NULL. This task_struct can't
go away, but task_active_pid_ns(task) is NULL if release_task(task)
was already called. Alternatively we could change get_pid_ns(ns) to
check ns != NULL, but it seems that other callers are fine.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Eric W. Biederman ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 kernel/pid_namespace.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--
1.9.1
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Patch

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 601bb36..2a953de 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -312,7 +312,9 @@  static void *pidns_get(struct task_struct *task)
 	struct pid_namespace *ns;

 	rcu_read_lock();
-	ns = get_pid_ns(task_active_pid_ns(task));
+	ns = task_active_pid_ns(task);
+	if (ns)
+		get_pid_ns(ns);
 	rcu_read_unlock();

 	return ns;