pid_namespace: pidns_get() should check task_active_pid_ns() != NULL
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>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 06c62de..db95d8e 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -318,7 +318,9 @@
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;