Subject: CVE-2021-47583: media: mxl111sf: change mutex_init() location

From: Greg Kroah-Hartman <[email-masked]>

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.

The Linux kernel CVE team has assigned CVE-2021-47583 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 3.7 with commit 8572211842af and fixed in 4.19.222 with commit 4b2d9600b31f
	Issue introduced in 3.7 with commit 8572211842af and fixed in 5.4.168 with commit 96f182c9f48b
	Issue introduced in 3.7 with commit 8572211842af and fixed in 5.10.88 with commit b99bdf127af9
	Issue introduced in 3.7 with commit 8572211842af and fixed in 5.15.11 with commit 8c6fdf62bfe1
	Issue introduced in 3.7 with commit 8572211842af and fixed in 5.16 with commit 44870a9e7a3c

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47583
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/media/usb/dvb-usb-v2/mxl111sf.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	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