Kernel crash via uninitialized automatic cleanup pointers

Missing initialization in Linux kernel 6.12 through 6.12.1 allows local users to crash the kernel through thermal testing operations. In drivers/thermal/testing/zone.c, early returns from tt_add_tz, tt_del_tz, tt_zone_add_trip, and tt_zone_register_tz pass uninitialized __free pointers to cleanup handlers. The debugfs-based thermal testing facility must be present and locally exercised; the documented consequence is a kernel crash, not data disclosure or modification.