Subject: CVE-2021-47260: NFS: Fix a potential NULL dereference in nfs_get_client()

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

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

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

NFS: Fix a potential NULL dereference in nfs_get_client()

None of the callers are expecting NULL returns from nfs_get_client() so
this code will lead to an Oops.  It's better to return an error
pointer.  I expect that this is dead code so hopefully no one is
affected.

The Linux kernel CVE team has assigned CVE-2021-47260 to this issue.

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

	Issue introduced in 3.17 with commit 31434f496abb and fixed in 4.4.273 with commit fab8bfdfb4aa
	Issue introduced in 3.17 with commit 31434f496abb and fixed in 4.9.273 with commit a979e6010009
	Issue introduced in 3.17 with commit 31434f496abb and fixed in 4.14.237 with commit 634f17ff1d59
	Issue introduced in 3.17 with commit 31434f496abb and fixed in 4.19.195 with commit 4b380a7d84ef
	Issue introduced in 3.17 with commit 31434f496abb and fixed in 5.4.126 with commit 0057ecef9f32
	Issue introduced in 3.17 with commit 31434f496abb and fixed in 5.10.44 with commit 279ad78a00f8
	Issue introduced in 3.17 with commit 31434f496abb and fixed in 5.12.11 with commit 58ddf61f10b8
	Issue introduced in 3.17 with commit 31434f496abb and fixed in 5.13 with commit 09226e8303be

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-2021-47260
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:
	fs/nfs/client.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/fab8bfdfb4aac9e4e8363666333adfdf21e89106
	https://git.kernel.org/stable/c/a979e601000982a3ca693171a6d4dffc47f8ad00
	https://git.kernel.org/stable/c/634f17ff1d59905eb3b4bbbc00805961d08beaee
	https://git.kernel.org/stable/c/4b380a7d84ef2ce3f4f5bec5d8706ed937ac6502
	https://git.kernel.org/stable/c/0057ecef9f324007c0ba5fcca4ddd131178ce78b
	https://git.kernel.org/stable/c/279ad78a00f8b9c5ff24171a59297187a3bd44b7
	https://git.kernel.org/stable/c/58ddf61f10b8f9b7b1341644bfee2f1c6508d4e1
	https://git.kernel.org/stable/c/09226e8303beeec10f2ff844d2e46d1371dc58e0