From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89658: NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup
Date: Fri, 11 Sep 2026 21:45:47 +0200 [thread overview]
Message-ID: <2026091145-CVE-2026-89658-bc53@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup
nfs40_clean_admin_revoked() takes a stateid reference under
clp->cl_lock, drops nn->client_lock, and calls
nfsd4_drop_revoked_stid(), which dereferences the stateid's client
through s->sc_client->cl_lock. The stateid reference does not pin the
client, so a teardown racing the dropped lock can free the client
while nfsd4_drop_revoked_stid() is still using it.
This cleanup runs from the laundromat, so a periodic sweep can race
force_expire_client() driven by a write to the clients/<id>/ctl file.
Skip a client that is already expiring and otherwise pin it with
cl_rpc_users under client_lock before dropping the lock, matching
nfsd4_revoke_states().
The Linux kernel CVE team has assigned CVE-2026-89658 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.9 with commit d688d8585e6bea5e4e37f7497feea93b6b0a469c and fixed in 6.12.109 with commit 0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519
Issue introduced in 6.9 with commit d688d8585e6bea5e4e37f7497feea93b6b0a469c and fixed in 6.18.50 with commit b413ec5b23e3445dc9c4f273116078e2d4747626
Issue introduced in 6.9 with commit d688d8585e6bea5e4e37f7497feea93b6b0a469c and fixed in 7.2.4 with commit 81cf7f1413862f87b078920c838460a6a88aa030
Issue introduced in 6.9 with commit d688d8585e6bea5e4e37f7497feea93b6b0a469c and fixed in 7.3-rc1 with commit 7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55
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-2026-89658
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/0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519
https://git.kernel.org/stable/c/b413ec5b23e3445dc9c4f273116078e2d4747626
https://git.kernel.org/stable/c/81cf7f1413862f87b078920c838460a6a88aa030
https://git.kernel.org/stable/c/7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55
reply other threads:[~2026-09-11 20:01 UTC|newest]
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