linux-cve-announce - CVE-2025-38567: nfsd: avoid ref leak in nfsd_open_local

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Message-ID: <2025081909-CVE-2025-38567-3597@gregkh>
Date: Tue, 19 Aug 2025 19:18:14 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38567: nfsd: avoid ref leak in nfsd_open_local_fh()

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

nfsd: avoid ref leak in nfsd_open_local_fh()

If two calls to nfsd_open_local_fh() race and both successfully call
nfsd_file_acquire_local(), they will both get an extra reference to the
net to accompany the file reference stored in *pnf.

One of them will fail to store (using xchg()) the file reference in
*pnf and will drop that reference but WON'T drop the accompanying
reference to the net.  This leak means that when the nfs server is shut
down it will hang in nfsd_shutdown_net() waiting for
&nn->nfsd_net_free_done.

This patch adds the missing nfsd_net_put().

The Linux kernel CVE team has assigned CVE-2025-38567 to this issue.


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

	Issue introduced in 6.15.3 with commit 986a21ace186433e0397a59491646edad8c8d636 and fixed in 6.15.10 with commit fcb0a417fddb605530c4837e0996620f8ed38023
	Issue introduced in 6.16 with commit e6f7e1487ab528a6c653bd0d42812ff2942846cd and fixed in 6.16.1 with commit c4bf8f26c51e51bbb840935659a7b3b65a802c07
	Issue introduced in 6.16 with commit e6f7e1487ab528a6c653bd0d42812ff2942846cd and fixed in 6.17-rc2 with commit e5a73150776f18547ee685c9f6bfafe549714899

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-2025-38567
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/localio.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/fcb0a417fddb605530c4837e0996620f8ed38023
	https://git.kernel.org/stable/c/c4bf8f26c51e51bbb840935659a7b3b65a802c07
	https://git.kernel.org/stable/c/e5a73150776f18547ee685c9f6bfafe549714899