Subject: CVE-2021-47176: s390/dasd: add missing discipline function

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

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

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

s390/dasd: add missing discipline function

Fix crash with illegal operation exception in dasd_device_tasklet.
Commit b72949328869 ("s390/dasd: Prepare for additional path event handling")
renamed the verify_path function for ECKD but not for FBA and DIAG.
This leads to a panic when the path verification function is called for a
FBA or DIAG device.

Fix by defining a wrapper function for dasd_generic_verify_path().

The Linux kernel CVE team has assigned CVE-2021-47176 to this issue.

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

	Issue introduced in 5.4.235 with commit 8bc5a76268fb and fixed in 5.4.237 with commit 6a16810068e7
	Issue introduced in 5.10.173 with commit 72aebdac390b and fixed in 5.10.175 with commit aa8579bc0846
	Issue introduced in 5.11 with commit b72949328869 and fixed in 5.12.9 with commit a16be88a3d7e
	Issue introduced in 5.11 with commit b72949328869 and fixed in 5.13 with commit c0c8a8397fa8

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-2021-47176
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/s390/block/dasd_diag.c
	drivers/s390/block/dasd_fba.c
	drivers/s390/block/dasd_int.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/6a16810068e70959bc1df686424aa35ce05578f1
	https://git.kernel.org/stable/c/aa8579bc084673c651204f7cd0d6308a47dffc16
	https://git.kernel.org/stable/c/a16be88a3d7e5efcb59a15edea87a8bd369630c6
	https://git.kernel.org/stable/c/c0c8a8397fa8a74d04915f4d3d28cb4a5d401427