Subject: CVE-2021-47587: net: systemport: Add global locking for descriptor lifecycle

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

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

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

net: systemport: Add global locking for descriptor lifecycle

The descriptor list is a shared resource across all of the transmit queues, and
the locking mechanism used today only protects concurrency across a given
transmit queue between the transmit and reclaiming. This creates an opportunity
for the SYSTEMPORT hardware to work on corrupted descriptors if we have
multiple producers at once which is the case when using multiple transmit
queues.

This was particularly noticeable when using multiple flows/transmit queues and
it showed up in interesting ways in that UDP packets would get a correct UDP
header checksum being calculated over an incorrect packet length. Similarly TCP
packets would get an equally correct checksum computed by the hardware over an
incorrect packet length.

The SYSTEMPORT hardware maintains an internal descriptor list that it re-arranges
when the driver produces a new descriptor anytime it writes to the
WRITE_PORT_{HI,LO} registers, there is however some delay in the hardware to
re-organize its descriptors and it is possible that concurrent TX queues
eventually break this internal allocation scheme to the point where the
length/status part of the descriptor gets used for an incorrect data buffer.

The fix is to impose a global serialization for all TX queues in the short
section where we are writing to the WRITE_PORT_{HI,LO} registers which solves
the corruption even with multiple concurrent TX queues being used.

The Linux kernel CVE team has assigned CVE-2021-47587 to this issue.

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

	Issue introduced in 3.16 with commit 80105befdb4b and fixed in 4.4.296 with commit 8ed2f5d08d6e
	Issue introduced in 3.16 with commit 80105befdb4b and fixed in 4.9.294 with commit de57f62f7645
	Issue introduced in 3.16 with commit 80105befdb4b and fixed in 4.14.259 with commit f3fde37d3f0d
	Issue introduced in 3.16 with commit 80105befdb4b and fixed in 4.19.222 with commit 595a684fa6f2
	Issue introduced in 3.16 with commit 80105befdb4b and fixed in 5.4.168 with commit c675256a7f13
	Issue introduced in 3.16 with commit 80105befdb4b and fixed in 5.10.88 with commit 6e1011cd183f
	Issue introduced in 3.16 with commit 80105befdb4b and fixed in 5.15.11 with commit eb4687c74429
	Issue introduced in 3.16 with commit 80105befdb4b and fixed in 5.16 with commit 8b8e6e782456

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-2021-47587
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/broadcom/bcmsysport.c
	drivers/net/ethernet/broadcom/bcmsysport.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/8ed2f5d08d6e59f8c78b2869bfb95d0be32c094c
	https://git.kernel.org/stable/c/de57f62f76450b934de8203711bdc4f7953c3421
	https://git.kernel.org/stable/c/f3fde37d3f0d429f0fcce214cb52588a9e21260e
	https://git.kernel.org/stable/c/595a684fa6f23b21958379a18cfa83862c73c2e1
	https://git.kernel.org/stable/c/c675256a7f131f5ba3f331efb715e8f31ea0e392
	https://git.kernel.org/stable/c/6e1011cd183faae8daff275c72444edcdfe0d473
	https://git.kernel.org/stable/c/eb4687c7442942e115420a30185f8d83faf37696
	https://git.kernel.org/stable/c/8b8e6e782456f1ce02a7ae914bbd5b1053f0b034