CVE-2021-47583 Information

Description

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.

Reference

https://git.kernel.org/stable/c/4b2d9600b31f9ba7adbc9f3c54a068615d27b390 https://git.kernel.org/stable/c/96f182c9f48b984447741f054ec301fdc8517035 https://git.kernel.org/stable/c/b99bdf127af91d53919e96292c05f737c45ea59a https://git.kernel.org/stable/c/8c6fdf62bfe1bc72bfceeaf832ef7499c7ed09ba https://git.kernel.org/stable/c/44870a9e7a3c24acbb3f888b2a7cc22c9bdf7e7f