CVE-2022-49587: tcp: Fix a data-race around sysctl_tcp_notsent_lowat.

CVE-2022-49587: tcp: Fix a data-race around sysctl_tcp_notsent_lowat.

[Greg Kroah-Hartman]

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

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

tcp: Fix a data-race around sysctl_tcp_notsent_lowat.

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

The Linux kernel CVE team has assigned CVE-2022-49587 to this issue.


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

	Issue introduced in 3.12 with commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36 and fixed in 4.9.325 with commit 91e21df688f8a75255ca9c459da39ac96300113a
	Issue introduced in 3.12 with commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36 and fixed in 4.14.290 with commit c1b85c5a34294f7444c13bf828e0e84b0a0eed85
	Issue introduced in 3.12 with commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36 and fixed in 4.19.254 with commit 0f75343584ee474303e17efe0610bdd170af1d13
	Issue introduced in 3.12 with commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36 and fixed in 5.4.208 with commit e9362a993886613ef0284c2a4911c6017c97d803
	Issue introduced in 3.12 with commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36 and fixed in 5.10.134 with commit fd6f1284e380c377932186042ff0b5c987fb2b92
	Issue introduced in 3.12 with commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36 and fixed in 5.15.58 with commit 80d4d0c461674eea87f0977e12a2ecd334b9b79c
	Issue introduced in 3.12 with commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36 and fixed in 5.18.15 with commit 62e56cfeb2ae4b53ae9ca24c80f54093250ce64a
	Issue introduced in 3.12 with commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36 and fixed in 5.19 with commit 55be873695ed8912eb77ff46d1d1cadf028bd0f3

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-2022-49587
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/tcp.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/91e21df688f8a75255ca9c459da39ac96300113a
	https://git.kernel.org/stable/c/c1b85c5a34294f7444c13bf828e0e84b0a0eed85
	https://git.kernel.org/stable/c/0f75343584ee474303e17efe0610bdd170af1d13
	https://git.kernel.org/stable/c/e9362a993886613ef0284c2a4911c6017c97d803
	https://git.kernel.org/stable/c/fd6f1284e380c377932186042ff0b5c987fb2b92
	https://git.kernel.org/stable/c/80d4d0c461674eea87f0977e12a2ecd334b9b79c
	https://git.kernel.org/stable/c/62e56cfeb2ae4b53ae9ca24c80f54093250ce64a
	https://git.kernel.org/stable/c/55be873695ed8912eb77ff46d1d1cadf028bd0f3