[PATCH 0/1] pid_namespace: pidns_get() should check task_active_pid_ns() != NULL

From: Oleg Nesterov
Date: Wed Apr 02 2014 - 12:45:46 EST


On 04/02, Oleg Nesterov wrote:
>
> Especially because this code needs a fix. Yes, rcu_read_lock() should
> be enough to ensure that ->parent and its namespace (if !NULL) can not
> go away, but task_active_pid_ns() can return NULL release_task(->parent)
> was already (although this race is pure theoretical). So this helper
> should also check it is !NULL under rcu_read_lock(), afaics.
>
> (Hmm... off-topic, but get_pidns looks buggy by the same reason, I'll
> send a fix).

Eric, I have to admit that I din't bother to actually verify this, but
pidns_get() looks "obviously buggy". Could you ack/nack ?

Oleg.

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