ptrace: do_notify_parent_cldstop: fix the wrong ->nsproxy usage

If the non-traced sub-thread calls do_notify_parent_cldstop(), we send the
notification to group_leader->real_parent and we report group_leader's
pid.

But, if group_leader is traced we use the wrong ->parent->nsproxy->pid_ns,
the tracer and parent can live in different namespaces.  Change the code
to use "parent" instead of tsk->parent.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 09ccc1c0e1f8..ccf1ceedaebe 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1499,7 +1499,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
          * see comment in do_notify_parent() abot the following 3 lines
          */
         rcu_read_lock();
-        info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
+        info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
         info.si_uid = __task_cred(tsk)->uid;
         rcu_read_unlock();