Mariadb-MDEV-16039

• Behavior: Server Crash (Segmentation fault / [ERROR] mysqld got signal 11;)
• Crash version: mariadb 10.3.8, 10.3.9
• Root Cause: Null Pointer Dereference
• Sketch:
  • Backtrace from gdb: in Item_args::walk_args (this=0x7fffb8088b88, processor=&virtual table offset 776, walk_subquery=false, arg=0x0) at /home/ry4nzzz/server/sql/item.h:2184 and local variablei = 0.
  • The function bool walk_args(Item_processor processor, bool walk_subquery, void *arg), a line if (args[i]->walk(processor, walk_subquery, arg)) access Item **args and args[0] is null pointer.
• Fixed Version: Latest 10.4.6