CVE-2026-74316: NFSD: Handle layout stid in nfsd4_drop_revoked_stid()

CVE-2026-74316: NFSD: Handle layout stid in nfsd4_drop_revoked_stid()

[Greg Kroah-Hartman]

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

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

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

NFSD: Handle layout stid in nfsd4_drop_revoked_stid()

nfsd4_drop_revoked_stid() has no SC_TYPE_LAYOUT case, so when a
client sends FREE_STATEID for an admin-revoked layout stid, the
default branch releases cl_lock and returns without unhashing or
releasing the stid.  The stid remains in the IDR and on the
per-client list until the client is destroyed.

Remove the layout stid from the per-client list and call
nfs4_put_stid() to drop the creation reference.  When the
refcount reaches zero, nfsd4_free_layout_stateid() handles the
remaining cleanup: cancelling the fence worker, removing from
the per-file list, and freeing the slab object.

The Linux kernel CVE team has assigned CVE-2026-74316 to this issue.


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

	Issue introduced in 6.9 with commit 1e33e1414bec54a4feafa9e67e2617031be0afe2 and fixed in 6.12.97 with commit 7ed62f7040ee182cf7dea5798f9e114235b31dae
	Issue introduced in 6.9 with commit 1e33e1414bec54a4feafa9e67e2617031be0afe2 and fixed in 6.18.40 with commit da6f86ff4f2dd490bea52419a49e19680efd5847
	Issue introduced in 6.9 with commit 1e33e1414bec54a4feafa9e67e2617031be0afe2 and fixed in 7.1.5 with commit 8024028ef91616cf91cc669f2446a0406bc0ba19
	Issue introduced in 6.9 with commit 1e33e1414bec54a4feafa9e67e2617031be0afe2 and fixed in 7.2-rc1 with commit 86b9898920a6d02b4149f4fef9efd77b8aa3b9ca

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-2026-74316
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/7ed62f7040ee182cf7dea5798f9e114235b31dae
	https://git.kernel.org/stable/c/da6f86ff4f2dd490bea52419a49e19680efd5847
	https://git.kernel.org/stable/c/8024028ef91616cf91cc669f2446a0406bc0ba19
	https://git.kernel.org/stable/c/86b9898920a6d02b4149f4fef9efd77b8aa3b9ca