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Commit e4da026f authored by Sukadev Bhattiprolu's avatar Sukadev Bhattiprolu Committed by Linus Torvalds
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signals: zap_pid_ns_process() should use force_sig() 



send_signal() assumes that signals with SEND_SIG_PRIV are generated from
within the same namespace.  So any nested container-init processes become
immune to the SIGKILL generated by kill_proc_info() in
zap_pid_ns_processes().

Use force_sig() in zap_pid_ns_processes() instead - force_sig() clears the
SIGNAL_UNKILLABLE flag ensuring the signal is processed by
container-inits.

Signed-off-by: default avatarSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 921cf9f6

kernel/pid_namespace.c

+14 −1
Original line number Diff line number Diff line
@@ -152,6 +152,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) 
{

	int nr;

	int rc;

	struct task_struct *task;



	/*

	 * The last thread in the cgroup-init thread group is terminating.
@@ -169,7 +170,19 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) 
	read_lock(&tasklist_lock);

	nr = next_pidmap(pid_ns, 1);

	while (nr > 0) {

		kill_proc_info(SIGKILL, SEND_SIG_PRIV, nr);

		rcu_read_lock();



		/*

		 * Use force_sig() since it clears SIGNAL_UNKILLABLE ensuring

		 * any nested-container's init processes don't ignore the

		 * signal

		 */

		task = pid_task(find_vpid(nr), PIDTYPE_PID);

		if (task)

			force_sig(SIGKILL, task);



		rcu_read_unlock();



		nr = next_pidmap(pid_ns, nr);

	}

	read_unlock(&tasklist_lock);