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Commit 9e8f90df authored by Oleg Nesterov's avatar Oleg Nesterov Committed by David S. Miller
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proc_fork_connector: a lockless ->real_parent usage is not safe 



proc_fork_connector() uses ->real_parent lockless.  This is not safe if
copy_process() was called with CLONE_THREAD or CLONE_PARENT, in this case
the parent != current can go away at any moment.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Vladimir Zapolskiy <vzapolskiy@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 177c27bf

drivers/connector/cn_proc.c

+6 −2
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ void proc_fork_connector(struct task_struct *task) 
	struct proc_event *ev;

	__u8 buffer[CN_PROC_MSG_SIZE];

	struct timespec ts;

	struct task_struct *parent;



	if (atomic_read(&proc_event_num_listeners) < 1)

		return;
@@ -67,8 +68,11 @@ void proc_fork_connector(struct task_struct *task) 
	ktime_get_ts(&ts); /* get high res monotonic timestamp */

	put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);

	ev->what = PROC_EVENT_FORK;

	ev->event_data.fork.parent_pid = task->real_parent->pid;

	ev->event_data.fork.parent_tgid = task->real_parent->tgid;

	rcu_read_lock();

	parent = rcu_dereference(task->real_parent);

	ev->event_data.fork.parent_pid = parent->pid;

	ev->event_data.fork.parent_tgid = parent->tgid;

	rcu_read_unlock();

	ev->event_data.fork.child_pid = task->pid;

	ev->event_data.fork.child_tgid = task->tgid;