CVE-2022-49103: NFSv4.2: fix reference count leaks in _nfs42_proc_copy_notify()

CVE-2022-49103: NFSv4.2: fix reference count leaks in _nfs42_proc_copy_notify()

[Greg Kroah-Hartman]

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

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

NFSv4.2: fix reference count leaks in _nfs42_proc_copy_notify()

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The reference counting issue happens in two error paths in the
function _nfs42_proc_copy_notify(). In both error paths, the function
simply returns the error code and forgets to balance the refcount of
object `ctx`, bumped by get_nfs_open_context() earlier, which may
cause refcount leaks.

Fix it by balancing refcount of the `ctx` object before the function
returns in both error paths.

The Linux kernel CVE team has assigned CVE-2022-49103 to this issue.


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

	Fixed in 5.10.111 with commit 9b9feec97c1fc7dd9bb69f62c4905cddf1801599
	Fixed in 5.15.34 with commit b37f482ba9f0e6382c188e3fccf6c4b2fdc938eb
	Fixed in 5.16.20 with commit fb73bf6305f4eb8f0cf9a61ee874d55f019d6dc4
	Fixed in 5.17.3 with commit f46f632f9cfae4b2e3635fa58840a8ec584c42e3
	Fixed in 5.18 with commit b7f114edd54326f730a754547e7cfb197b5bc132

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-2022-49103
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/nfs42proc.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/9b9feec97c1fc7dd9bb69f62c4905cddf1801599
	https://git.kernel.org/stable/c/b37f482ba9f0e6382c188e3fccf6c4b2fdc938eb
	https://git.kernel.org/stable/c/fb73bf6305f4eb8f0cf9a61ee874d55f019d6dc4
	https://git.kernel.org/stable/c/f46f632f9cfae4b2e3635fa58840a8ec584c42e3
	https://git.kernel.org/stable/c/b7f114edd54326f730a754547e7cfb197b5bc132