1 files changed, 22 insertions, 0 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 7d4a9a6df956..b07adca97ea3 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2063,6 +2063,24 @@ static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
 }
 #endif
 
+static int propagate_has_child_subreaper(struct task_struct *p, void *data)
+{
+        /*
+         * If task has has_child_subreaper - all its decendants
+         * already have these flag too and new decendants will
+         * inherit it on fork, skip them.
+         *
+         * If we've found child_reaper - skip descendants in
+         * it's subtree as they will never get out pidns.
+         */
+        if (p->signal->has_child_subreaper ||
+            is_child_reaper(task_pid(p)))
+                return 0;
+
+        p->signal->has_child_subreaper = 1;
+        return 1;
+}
+
 SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
                 unsigned long, arg4, unsigned long, arg5)
 {
@@ -2214,6 +2232,10 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
                 break;
         case PR_SET_CHILD_SUBREAPER:
                 me->signal->is_child_subreaper = !!arg2;
+                if (!arg2)
+                        break;
+
+                walk_process_tree(me, propagate_has_child_subreaper, NULL);
                 break;
         case PR_GET_CHILD_SUBREAPER:
                 error = put_user(me->signal->is_child_subreaper,