Subject: CVE-2021-47388: mac80211: fix use-after-free in CCMP/GCMP RX

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

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

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

mac80211: fix use-after-free in CCMP/GCMP RX

When PN checking is done in mac80211, for fragmentation we need
to copy the PN to the RX struct so we can later use it to do a
comparison, since commit bf30ca922a0c ("mac80211: check defrag
PN against current frame").

Unfortunately, in that commit I used the 'hdr' variable without
it being necessarily valid, so use-after-free could occur if it
was necessary to reallocate (parts of) the frame.

Fix this by reloading the variable after the code that results
in the reallocations, if any.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=214401.

The Linux kernel CVE team has assigned CVE-2021-47388 to this issue.

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

	Issue introduced in 4.4.271 with commit 608b0a2ae928 and fixed in 4.4.286 with commit 447d001b875d
	Issue introduced in 4.9.271 with commit d0f613fe6de3 and fixed in 4.9.285 with commit 31de381aef0a
	Issue introduced in 4.14.235 with commit a9b57952fed4 and fixed in 4.14.249 with commit f556e1d6fb9f
	Issue introduced in 4.19.193 with commit 0f716b48ed25 and fixed in 4.19.209 with commit 3d5d629c99c4
	Issue introduced in 5.4.124 with commit c8b3a6150dc8 and fixed in 5.4.151 with commit 50149e0866a8
	Issue introduced in 5.10.42 with commit e64ea0597050 and fixed in 5.10.71 with commit 57de2dcb1874
	Issue introduced in 5.13 with commit bf30ca922a0c and fixed in 5.14.10 with commit 27d3eb5616ee
	Issue introduced in 5.13 with commit bf30ca922a0c and fixed in 5.15 with commit 94513069eb54
	Issue introduced in 5.12.9 with commit 1f0bf30c01d3

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-2021-47388
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/mac80211/wpa.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/447d001b875d0e7f211c4ba004916028da994258
	https://git.kernel.org/stable/c/31de381aef0ab1b342f62485118dc8a19363dc78
	https://git.kernel.org/stable/c/f556e1d6fb9f2923a9a36f3df638c7d79ba09dbb
	https://git.kernel.org/stable/c/3d5d629c99c468458022e9b381789de3595bf4dd
	https://git.kernel.org/stable/c/50149e0866a82cef33e680ee68dc380a5bc75d32
	https://git.kernel.org/stable/c/57de2dcb18742dc2860861c9f496da7d42b67da0
	https://git.kernel.org/stable/c/27d3eb5616ee2c0a3b30c3fa34813368ed1f3dc9
	https://git.kernel.org/stable/c/94513069eb549737bcfc3d988d6ed4da948a2de8