CVE-2022-49577: udp: Fix a data-race around sysctl_udp_l3mdev_accept.

CVE-2022-49577: udp: Fix a data-race around sysctl_udp_l3mdev_accept.

[Greg Kroah-Hartman]

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

udp: Fix a data-race around sysctl_udp_l3mdev_accept.

While reading sysctl_udp_l3mdev_accept, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

The Linux kernel CVE team has assigned CVE-2022-49577 to this issue.


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

	Issue introduced in 4.11 with commit 63a6fff353d01da5a22b72670c434bf12fa0e3b8 and fixed in 5.4.208 with commit f39b03bd727a8fea62e82f10fe2e0d753b9930ff
	Issue introduced in 4.11 with commit 63a6fff353d01da5a22b72670c434bf12fa0e3b8 and fixed in 5.10.134 with commit fcaef69c79ec222e55643e666b80b221e70fa6a8
	Issue introduced in 4.11 with commit 63a6fff353d01da5a22b72670c434bf12fa0e3b8 and fixed in 5.15.58 with commit 3f2ac2d6511bb0652abf4d7388d65bb9ff1c641c
	Issue introduced in 4.11 with commit 63a6fff353d01da5a22b72670c434bf12fa0e3b8 and fixed in 5.18.15 with commit cb0d28934ca10f99c47e2c6f451405d6c954fe48
	Issue introduced in 4.11 with commit 63a6fff353d01da5a22b72670c434bf12fa0e3b8 and fixed in 5.19 with commit 3d72bb4188c708bb16758c60822fc4dda7a95174

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-2022-49577
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:
	include/net/udp.h


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/f39b03bd727a8fea62e82f10fe2e0d753b9930ff
	https://git.kernel.org/stable/c/fcaef69c79ec222e55643e666b80b221e70fa6a8
	https://git.kernel.org/stable/c/3f2ac2d6511bb0652abf4d7388d65bb9ff1c641c
	https://git.kernel.org/stable/c/cb0d28934ca10f99c47e2c6f451405d6c954fe48
	https://git.kernel.org/stable/c/3d72bb4188c708bb16758c60822fc4dda7a95174