2 files changed, 8 insertions, 2 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 0291a68a3626..4d38ad0b70d6 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -723,7 +723,12 @@ static int de_thread(struct task_struct *tsk)
                 current->parent = current->real_parent = leader->real_parent;
                 leader->parent = leader->real_parent = child_reaper;
                 current->group_leader = current;
-                leader->group_leader = leader;
+                leader->group_leader = current;
+
+                /* Reduce leader to a thread */
+                detach_pid(leader, PIDTYPE_PGID);
+                detach_pid(leader, PIDTYPE_SID);
+                list_del_init(&leader->tasks);
 
                 add_parent(current);
                 add_parent(leader);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 541f4828f5e7..a3e4f6b503a3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1203,7 +1203,8 @@ extern void wait_task_inactive(task_t * p);
 #define while_each_thread(g, t) \
         while ((t = next_thread(t)) != g)
 
-#define thread_group_leader(p)  (p->pid == p->tgid)
+/* de_thread depends on thread_group_leader not being a pid based check */
+#define thread_group_leader(p)  (p == p->group_leader)
 
 static inline task_t *next_thread(task_t *p)
 {