From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E2B2258E2D4 for ; Fri, 11 Sep 2026 20:03:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157023; cv=none; b=QdU50v6aMFtFoRPjU6eahFpwao1Kr1CzQJgUbaMnSAbup8WqUoaBhuN/xdsdCwmdaOdYvUZGij4LoDpLu4770qzJVRlIyAkz2NbQhvx5u6ZIGP7L4fLT1li4cORMZrenmyOOTkZ43pLi3wsoF+jGUsLT6BCYefj7wqPuo3jlcTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157023; c=relaxed/simple; bh=bHs4nyktmcbdW1pWHFGlv0MofWFKYEjew4DSpFaTex0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ok2bcg5Ec/puHxPeGWotqak+GMzfwbWzf165u6FOLxOckS556Gzl+j6A/Ka0TIC/xFJ5QQpwZ0ksVQyHvY2NcfaDIFgTp9kTcohA5PMFwFlRW/U3m063YYt7YMrbOPd+S/K7M51xmmhJGga/aCz/ZXZEcfpwu6xH1W7IIK/3Tic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fbCfzeDB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fbCfzeDB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5DE211F0089B; Fri, 11 Sep 2026 20:03:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789157009; bh=ToHCiM8qXCLh14QEX3sHBAep02U8WnuGgwzS4TpXDz4=; h=From:To:Cc:Subject:Date:Reply-To; b=fbCfzeDBDACm67D/V9lwf3ZejBEknBbxHcaopsHmuR1tOTCPLsA/1lEAuj8/TF2La IUR6A/fY98hRCR1jH9p67kbbzvOg5rxvZgY1hVmH2XToqvIgNXnPC4p/Y6yAhEMxy1 Zgmi4GBcJ5zqvXQ/fiwNn7kAF0cbQSlArwEPLJJA= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89662: NFSD: Prevent lock owner use-after-free during client teardown Date: Fri, 11 Sep 2026 21:45:51 +0200 Message-ID: <2026091146-CVE-2026-89662-3d7c@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3543; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=DghtLFZqmIrkTIaVPC+UdQ3m7mmxVAbbEw4NJqA6+wo=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIqsOpzGYG+64qbWz9j7fJ9vgZ3dDSi/kFs+Zc2L/b yln27ZDHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjAR+UiGeTruXRN+ebtFqts9 5l5yMv9mckjjIoYFiw/nrf/VqXjmtsdljlqx7ItLF4f6AgA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent lock owner use-after-free during client teardown __destroy_client() releases a client's open owners, but a lock owner whose only reference is a blocked lock (nbl) stays on cl_ownerstr_hashtbl. client_has_state() does not count a bare owner, so DESTROY_CLIENTID can reach __destroy_client() with such owners present. __destroy_client() then walks the table, calling remove_blocked_locks() on each owner without a reference. Freeing a blocked lock drops the owner reference held via flc_owner. The per-net laundromat reaps blocked locks from nn->blocked_locks_lru independently of client state. The two paths share blocked_locks_lock only for the list splice, not the owner's lifetime. The laundromat therefore frees the owner as __destroy_client() dereferences it, a NULL dereference in remove_blocked_locks(). nfsd4_release_lockowner() holds a reference across the same call; __destroy_client() does not. Hold cl_lock across the walk, taking a reference and unhashing each owner, then drop it before remove_blocked_locks() and nfs4_put_stateowner(), which take blocked_locks_lock and cl_lock. The Linux kernel CVE team has assigned CVE-2026-89662 to this issue. Affected and fixed versions =========================== Issue introduced in 4.16 with commit 68ef3bc3166468678d5e1fdd216628c35bd1186f and fixed in 6.12.109 with commit a6ead6fff3a7d03e49845f048f7000a2e0d34431 Issue introduced in 4.16 with commit 68ef3bc3166468678d5e1fdd216628c35bd1186f and fixed in 6.18.50 with commit 4804c58f73a80d12df1de323bf97a164f6ee8743 Issue introduced in 4.16 with commit 68ef3bc3166468678d5e1fdd216628c35bd1186f and fixed in 7.2.4 with commit 8cf4ff0a7c083dd5e0067f517d63979b74b66649 Issue introduced in 4.16 with commit 68ef3bc3166468678d5e1fdd216628c35bd1186f and fixed in 7.3-rc1 with commit 5e2fa29d223a9a1e6a948e40b109d09081d1decd Issue introduced in 4.9.91 with commit e294c4c2d33b7307a89cdf31bec08a112d6a9297 Issue introduced in 4.14.31 with commit 797bfd05d4040fbf766198b3cfcc1838002cc890 Issue introduced in 4.15.14 with commit 0f44e9da465ea259b6c9f31a627f3c50a16e1679 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-2026-89662 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/a6ead6fff3a7d03e49845f048f7000a2e0d34431 https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743 https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649 https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd