CVE-2026-74730: NFS: Pin the 'struct nfs_server' during a FREE_STATEID call

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

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

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

NFS: Pin the 'struct nfs_server' during a FREE_STATEID call

Dan Aloni reports that he was able to hit a use-after-free bug if a
FREE_STATEID operation gets delayed for whatever reason. Fix this by
bumping the refcount of the 'struct nfs_server' object for the duration
of the FREE_STATEID so it doesn't get cleaned up from underneath us
while operations are still in flight.

The Linux kernel CVE team has assigned CVE-2026-74730 to this issue.


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

	Issue introduced in 3.10 with commit 7c1d5fae4a87d3cf3e9ffd68bcdbaf6529013009 and fixed in 5.10.265 with commit ed2f92ce2fc48463c41e0e540b9a3454889e8af8
	Issue introduced in 3.10 with commit 7c1d5fae4a87d3cf3e9ffd68bcdbaf6529013009 and fixed in 5.15.216 with commit d858ab09e787106432d4d9830bad9dfedf02f890
	Issue introduced in 3.10 with commit 7c1d5fae4a87d3cf3e9ffd68bcdbaf6529013009 and fixed in 6.1.183 with commit af62f1af182d33a0de38308c012841885d8ab92e
	Issue introduced in 3.10 with commit 7c1d5fae4a87d3cf3e9ffd68bcdbaf6529013009 and fixed in 6.6.152 with commit caee6a68ffaa5016dfc01cd0b3dc1896a32e3abd
	Issue introduced in 3.10 with commit 7c1d5fae4a87d3cf3e9ffd68bcdbaf6529013009 and fixed in 6.12.104 with commit ed1161ab6239761958b38d5667225634fc2be894
	Issue introduced in 3.10 with commit 7c1d5fae4a87d3cf3e9ffd68bcdbaf6529013009 and fixed in 6.18.45 with commit d71dfffa512e71b166a889484e4c3b148a9a3af2
	Issue introduced in 3.10 with commit 7c1d5fae4a87d3cf3e9ffd68bcdbaf6529013009 and fixed in 7.1.9 with commit 80ed3d762628b36c9e4b22fac7c65b72ef3b13dd
	Issue introduced in 3.10 with commit 7c1d5fae4a87d3cf3e9ffd68bcdbaf6529013009 and fixed in 7.2 with commit cf616096a0f3a2b60f7d68b6b39674a6867ded9c

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-2026-74730
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/nfs4proc.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/ed2f92ce2fc48463c41e0e540b9a3454889e8af8
	https://git.kernel.org/stable/c/d858ab09e787106432d4d9830bad9dfedf02f890
	https://git.kernel.org/stable/c/af62f1af182d33a0de38308c012841885d8ab92e
	https://git.kernel.org/stable/c/caee6a68ffaa5016dfc01cd0b3dc1896a32e3abd
	https://git.kernel.org/stable/c/ed1161ab6239761958b38d5667225634fc2be894
	https://git.kernel.org/stable/c/d71dfffa512e71b166a889484e4c3b148a9a3af2
	https://git.kernel.org/stable/c/80ed3d762628b36c9e4b22fac7c65b72ef3b13dd
	https://git.kernel.org/stable/c/cf616096a0f3a2b60f7d68b6b39674a6867ded9c