The msm gpu driver for custom Linux kernels on the Xiaomi perseus-p-oss MIX 3 device through 2018-11-26 has an integer overflow and OOPS because of missing checks of the count argument in _sde_debugfs_conn_cmd_tx_write in drivers/gpu/drm/msm/sde/sde_connector.c. This is exploitable for a device crash via a syscall by a crafted application on a rooted device.