sched/group: skip group_release for kernel thread group

When CONFIG_DISABLE_PTHREAD=y, HAVE_GROUP_MEMBERS is undefined and
group_leave() unconditionally calls group_release() for every exiting
thread. This destroys the shared g_kthread_group resources (mutex,
fdlist, task_info) while other kernel threads are still using them,
causing use-after-free crashes.

Fix by checking TCB_FLAG_TTYPE_KERNEL in group_leave() before calling
group_release(), so the entire release path is skipped for kernel
threads. This is safe because g_kthread_group is statically allocated
and its lifetime is the entire system.

Signed-off-by: wangyongrong <wangyongrong@xiaomi.com>

Author: wyr-7

include/nuttx/sched.h

@@ -118,7 +118,7 @@
 #define GROUP_FLAG_DELETED         (1 << 2)                      /* Bit 2: Group has been deleted but not yet freed */
 #define GROUP_FLAG_EXITING         (1 << 3)                      /* Bit 3: Group exit is in progress */
 #define GROUP_FLAG_FD_BACKTRACE    (1 << 4)                      /* Bit 4: Enable FD backtrace for the group */
-                                                                 /* Bits 3-7: Available */
+                                                                 /* Bits 5-7: Available */
 
 /* Values for struct child_status_s ch_flags */
 

sched/group/group_leave.c

@@ -59,7 +59,7 @@
  *   Release group resources after the last member has left the group.
  *
  * Input Parameters:
- *   group - The group to be removed.
+ *   group - The group to be released.
  *
  * Returned Value:
  *   None.
@@ -173,17 +173,20 @@ void group_leave(FAR struct tcb_s *tcb)
   group = tcb->group;
   if (group)
     {
+      bool release = !(atomic_read(&tcb->flags) & TCB_FLAG_TTYPE_KERNEL);
+
       /* Remove the member from group. */
 
 #ifdef HAVE_GROUP_MEMBERS
       flags = spin_lock_irqsave(&group->tg_lock);
       sq_rem(&tcb->member, &group->tg_members);
+      release = release && sq_empty(&group->tg_members);
       spin_unlock_irqrestore(&group->tg_lock, flags);
 
       /* Have all of the members left the group? */
-
-      if (sq_empty(&group->tg_members))
 #endif
+
+      if (release)
         {
           /* Yes.. Release all of the resource held by the task group */