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 0996B58F09C for ; Fri, 11 Sep 2026 20:05:09 +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=1789157113; cv=none; b=bRsvRfWiciNjj/Kv1yoIjdyjnHX9giSOwx7UaIKyEaicpNM3+TSokhRDgdVZDA7NoebFCQo0/8NhTaQHUbVRtf8Ce6LoHCYBBw1nSlZi81tto6p9OhGbSBv4yFDsHUhKHJj0t7UaHuHam5LLUv+2PZloLtN4gptPIDZPiWksjXE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157113; c=relaxed/simple; bh=NVVLV402oe7OxwA8OFvaAft4InTfMqN2aNHrCfAmLpo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ZnzYwgugvmTKmq5ryvFgVwbCswtnAIFbvXlTIVkgKrt7j+AQIbw2Kb7v3YxlVpNJoQpQuHbmbnUaI21ylXGn7a/2TzAyK7v9TFM8CQxTgrD/SsoS+leNMxp876Q+tION7jdYdilwpuGZrbcFoKFUbtgWzKgoXE4OhypE06pgcDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=NiCJW7XF; 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="NiCJW7XF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 162031F00898; Fri, 11 Sep 2026 20:05:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789157108; bh=RmJJAYPDhg0yFmHXtUZT0a4xgu/sHP6LDHb4TDZPOF0=; h=From:To:Cc:Subject:Date:Reply-To; b=NiCJW7XF61z/zU1VMwGreUQNZh45dQE4euExLi54h3/NF3/BtiWrg23ciEL6+3kgr hKmSClX9Kd9bEgFzJ5ZGuCO1vBBjAGRbOza5yvAZTJ8ZfDJQaEnf2VmwQCHHSTs4uW bYRpSllOXqC7TxkIAqwELz7FVcTJiRGBYvDBeiPc= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89705: nfsd: restore rq_status_counter to even on all nfsd_dispatch() exit paths Date: Fri, 11 Sep 2026 21:46:34 +0200 Message-ID: <2026091156-CVE-2026-89705-323b@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=3014; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=pdUeRnUxLwJWh+EP+D4l1iakHccV2LIWuhHH2ODK/2g=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIlvcd9gZZ/w9u5l9efvuTu5zm67JTJpkLbQoyfTxO bP7zZNVOmJZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAivpsYFly/uWjV0357oyva a07a5EZX//7FfYBhDn/Q9MKqizpXO+TPVsz9bBGqoidqDwA= 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: restore rq_status_counter to even on all nfsd_dispatch() exit paths nfsd_dispatch() sets rq_status_counter to an odd value once a request has been decoded, and back to an even value once it has been fully processed, forming a seq-lock like protocol with the lockless reader in nfsd_nl_rpc_status_get_dumpit(). Only the fully successful path restored the counter to even. The cache-hit (RC_REPLY), drop (RC_DROPIT / RQ_DROPME) and encode-error paths all return after the odd-valued store without ever bringing the counter back to even. Once one of those paths is taken, rq_status_counter is left odd: the next request's decode ORs in 1 (still odd) and only a subsequent successful encode restores even. While stuck odd, the dumpit reader treats the rqstp fields as stable and its retry check compares against the same unchanging odd value, so it never detects concurrent mutation. This exposes actively mutating fields (e.g. args->ops / args->opcnt during compound decode and release) to the lockless reader, which can read past the end of the 8-element inline ops array. Add a helper that advances the counter to the next even value and call it on every return path that follows the odd-valued store. The decode-error path is left untouched as it is reached before the counter is set odd. The Linux kernel CVE team has assigned CVE-2026-89705 to this issue. Affected and fixed versions =========================== Issue introduced in 6.7 with commit bd9d6a3efa9709e653aafbeb859289feccb8e70c and fixed in 7.2.4 with commit b08c30f08d57f30699d36809d92f0b683dca261f Issue introduced in 6.7 with commit bd9d6a3efa9709e653aafbeb859289feccb8e70c and fixed in 7.3-rc1 with commit f6045886fe3f14f269f683d64021b004a50d0efa 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-2026-89705 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/nfssvc.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/b08c30f08d57f30699d36809d92f0b683dca261f https://git.kernel.org/stable/c/f6045886fe3f14f269f683d64021b004a50d0efa