EXT_IOCTL_SIGN_SZ
uint8_t signature[EXT_IOCTL_SIGN_SZ];
char signature[EXT_IOCTL_SIGN_SZ] = {0};
if (copy_from_user(signature, argp, EXT_IOCTL_SIGN_SZ)) {
if (memcmp(signature, EXT_IOCTL_SIGN, EXT_IOCTL_SIGN_SZ) == 0)