CVE-2021-47137: net: lantiq: fix memory corruption in RX ring

CVE-2021-47137: net: lantiq: fix memory corruption in RX ring

[Greg Kroah-Hartman]

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

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

net: lantiq: fix memory corruption in RX ring

In a situation where memory allocation or dma mapping fails, an
invalid address is programmed into the descriptor. This can lead
to memory corruption. If the memory allocation fails, DMA should
reuse the previous skb and mapping and drop the packet. This patch
also increments rx drop counter.

The Linux kernel CVE team has assigned CVE-2021-47137 to this issue.


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

	Issue introduced in 4.20 with commit fe1a56420cf2 and fixed in 5.4.124 with commit 8bb1077448d4
	Issue introduced in 4.20 with commit fe1a56420cf2 and fixed in 5.10.42 with commit 5ac72351655f
	Issue introduced in 4.20 with commit fe1a56420cf2 and fixed in 5.12.9 with commit 46dd4abced3c
	Issue introduced in 4.20 with commit fe1a56420cf2 and fixed in 5.13 with commit c7718ee96dbc

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-2021-47137
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/net/ethernet/lantiq_xrx200.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/8bb1077448d43a871ed667520763e3b9f9b7975d
	https://git.kernel.org/stable/c/5ac72351655f8b033a2935646f53b7465c903418
	https://git.kernel.org/stable/c/46dd4abced3cb2c912916f4a5353e0927db0c4a2
	https://git.kernel.org/stable/c/c7718ee96dbc2f9c5fc3b578abdf296dd44b9c20