Subject: CVE-2024-46690: nfsd: fix nfsd4_deleg_getattr_conflict in presence of third party lease

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

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

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

nfsd: fix nfsd4_deleg_getattr_conflict in presence of third party lease

It is not safe to dereference fl->c.flc_owner without first confirming
fl->fl_lmops is the expected manager.  nfsd4_deleg_getattr_conflict()
tests fl_lmops but largely ignores the result and assumes that flc_owner
is an nfs4_delegation anyway.  This is wrong.

With this patch we restore the "!= &nfsd_lease_mng_ops" case to behave
as it did before the change mentioned below.  This is the same as the
current code, but without any reference to a possible delegation.

The Linux kernel CVE team has assigned CVE-2024-46690 to this issue.

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

	Issue introduced in 6.9 with commit c5967721e106 and fixed in 6.10.8 with commit 1b46a871e980
	Issue introduced in 6.9 with commit c5967721e106 and fixed in 6.11 with commit 40927f3d0972

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-2024-46690
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/nfsd/nfs4state.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/1b46a871e980e3daa16fd5e77539966492e8910a
	https://git.kernel.org/stable/c/40927f3d0972bf86357a32a5749be71a551241b6