CVE-2021-47583

In the Linux kernel, the following vulnerability has been resolved: media:
mxl111sf: change mutex_init() location Syzbot reported, that
mxl111sf_ctrl_msg() uses uninitialized mutex. The problem was in wrong
mutex_init() location. Previous mutex_init(&state->msg_lock) call was in
->init() function, but dvb_usbv2_init() has this order of calls:
dvb_usbv2_init() dvb_usbv2_adapter_init() dvb_usbv2_adapter_frontend_init()
props->frontend_attach() props->init() Since mxl111sf_* devices call
mxl111sf_ctrl_msg() in ->frontend_attach() internally we need to initialize
state->msg_lock before frontend_attach(). To achieve it, ->probe() call
added to all mxl111sf_* devices, which will simply initiaize mutex.