The GCC and Clang attribute '__counted_by_ptr' associates a pointer field with an integer field holding its element count. This enables runtime bounds checking by KASAN and UBSAN to prevent out-of-bounds accesses to the pointer. In 'struct fw_device' (defined in 'include/linux/firewire.h'), the field 'config_rom' is a pointer to the device's Configuration ROM data, and its associated element count is stored in 'config_rom_length'. Additionally, update the existing KUnit test in 'drivers/firewire/device-attribute-test.c' where 'config_rom_length' was incorrectly initialized with the byte size ('sizeof(simple_avc_config_rom)') instead of the element count ('ARRAY_SIZE(simple_avc_config_rom)'). This ensures the '__counted_by_ptr' bounds-checking annotation does not trigger any false-positive panics or compile/runtime checks. Cc: codemender-patching+linux@google.com Assisted-by: LLM Signed-off-by: Bill Wendling <morbo@google.com> Link: https://lore.kernel.org/r/20260925212552.125652-1-morbo@google.com Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>