CVE-2021-47186: tipc: check for null after calling kmemdup

CVE-2021-47186: tipc: check for null after calling kmemdup

[Greg Kroah-Hartman]

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

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

tipc: check for null after calling kmemdup

kmemdup can return a null pointer so need to check for it, otherwise
the null key will be dereferenced later in tipc_crypto_key_xmit as
can be seen in the trace [1].


[1] https://syzkaller.appspot.com/bug?id=bca180abb29567b189efdbdb34cbf7ba851c2a58

The Linux kernel CVE team has assigned CVE-2021-47186 to this issue.


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

	Fixed in 5.10.82 with commit a7d91625863d
	Fixed in 5.15.5 with commit 9404c4145542
	Fixed in 5.16 with commit 3e6db079751a

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-2021-47186
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:
	net/tipc/crypto.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/a7d91625863d4ffed63b993b5e6dc1298b6430c9
	https://git.kernel.org/stable/c/9404c4145542c23019a80ab1bb2ecf73cd057b10
	https://git.kernel.org/stable/c/3e6db079751afd527bf3db32314ae938dc571916