Subject: CVE-2021-47183: scsi: lpfc: Fix link down processing to address NULL pointer dereference

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

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

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

scsi: lpfc: Fix link down processing to address NULL pointer dereference

If an FC link down transition while PLOGIs are outstanding to fabric well
known addresses, outstanding ABTS requests may result in a NULL pointer
dereference. Driver unload requests may hang with repeated "2878" log
messages.

The Link down processing results in ABTS requests for outstanding ELS
requests. The Abort WQEs are sent for the ELSs before the driver had set
the link state to down. Thus the driver is sending the Abort with the
expectation that an ABTS will be sent on the wire. The Abort request is
stalled waiting for the link to come up. In some conditions the driver may
auto-complete the ELSs thus if the link does come up, the Abort completions
may reference an invalid structure.

Fix by ensuring that Abort set the flag to avoid link traffic if issued due
to conditions where the link failed.

The Linux kernel CVE team has assigned CVE-2021-47183 to this issue.

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

	Fixed in 5.15.5 with commit 28de48a7cea4
	Fixed in 5.16 with commit 1854f53ccd88

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-2021-47183
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/scsi/lpfc/lpfc_sli.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/28de48a7cea495ab48082d9ff4ef63f7cb4e563a
	https://git.kernel.org/stable/c/1854f53ccd88ad4e7568ddfafafffe71f1ceb0a6