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 415AC58497B for ; Fri, 11 Sep 2026 20:00:46 +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=1789156856; cv=none; b=U1faIPp3TEswamH1t7UtV1Hw2p0jKH6ePnZE/mIE70rAViqTpMoyisYgP9HwbZ79PIvIvhmR74DkgFa3BY8B5Eek9VyOiR4/Vi+lKppr9CT2bAO1xrXfwFD6s/L08MLvf+C+7aeJOhW03Obbo+nWwOPS3TfLlQDf5L9uhCEfTWA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156856; c=relaxed/simple; bh=uG4Xkv9jpghLEuy8ARYuFBw9eeMTUESpyZiheXIic6g=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=p8o9XH3QJRGenWQkWeCBjd8U8lBomuVslGlVHARvuKE4bUC9IH73fgSs7kCgeIo5TMhUkyZ2e6Kn2uWaKMx6+WBA2hIO//fA2ih0WtfQrGzCW307AoYAvjIOlMlpx8xf0IujdfcWHDMQWFRORzF1QAxEop1AjIDtbpjE1YgabMs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Lq3Jk3Vl; 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="Lq3Jk3Vl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00FB91F00893; Fri, 11 Sep 2026 20:00:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156844; bh=X31iXcJhiT0nC/SGy7OA99ooR0AAsiU+bt07vrIUgJw=; h=From:To:Cc:Subject:Date:Reply-To; b=Lq3Jk3VlBwX06KQ9ZQ+JdpxhkGF773cCABtDp6wSU4hUWvCkoMxeaAMpW8jOZGn0q 9d1L7eLdgQK3OuJefTtn3o08w8JP7MwBpCdBPhI+KBKR27E8bP3A3ZiUJhiv1Chjbk bcheQ36tMt+5RG1s+GwVBtXkOWna5CI92hS6Dxdc= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89651: ceph: bound MDSCapAuth path and fs_name decode in handle_session() Date: Fri, 11 Sep 2026 21:45:40 +0200 Message-ID: <2026091144-CVE-2026-89651-7bbb@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=3670; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=GrkwO1ps50Y/SxYEikCnD369i+jzmt5571TF+oKKELw=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIisebbGTP6d9Y24Kh8DsPdvuyWobraqa2ynw+tip0 DTXV7NkOmJZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAiH40Y5spO3LProfWWdzlN AUUGqlKVYZxRbQzzk2ewXFidu9aXgd/lplRb9h2R2J+rAQ== 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: ceph: bound MDSCapAuth path and fs_name decode in handle_session() handle_session() decodes the MDSCapAuth records carried by a CEPH_SESSION_OPEN message (msg_version >= 6). For each record the match.path and match.fs_name byte strings are read by first decoding a 32-bit length and then copying that many bytes with the bare ceph_decode_copy(). Unlike the surrounding fields, which all use the _safe decode variants, these two copies are not preceded by a ceph_decode_need() bounds check, and the enclosing MDSCapAuth and MDSCapMatch struct_len fields are skipped rather than enforced as an upper bound. A length larger than the bytes remaining in the message front makes ceph_decode_copy() read past the end of the front buffer. The message front is a dedicated allocation (ceph_msg_new2() -> kvmalloc), so the over-read runs off that object. A malicious or compromised MDS can trigger this with the first post-connect message on mount, with no client-side user interaction; under KASAN it is reported as a slab-out-of-bounds read in handle_session(). Impact: a malicious MDS can force the kernel client to read up to 4 GiB past the message front allocation during session setup, crashing the client (out-of-bounds read). Switch both copies to ceph_decode_copy_safe(), which performs the ceph_decode_need() bounds check before the copy and branches to the existing bad label, matching the rest of the decoder and the error path that frees the partially decoded cap_auths array. The Linux kernel CVE team has assigned CVE-2026-89651 to this issue. Affected and fixed versions =========================== Issue introduced in 6.10 with commit 1d17de9534cb5a4c4c380d174cc2f9281b34f89e and fixed in 6.12.109 with commit dc5c7dffda92ef372fa587c444a1c537373df824 Issue introduced in 6.10 with commit 1d17de9534cb5a4c4c380d174cc2f9281b34f89e and fixed in 6.18.50 with commit c37db86d2b5e9b57001ccae7e7a727e95a4f9c02 Issue introduced in 6.10 with commit 1d17de9534cb5a4c4c380d174cc2f9281b34f89e and fixed in 7.2.4 with commit 5f892c767b30e4fb0c744c59f9235c717383d2cd Issue introduced in 6.10 with commit 1d17de9534cb5a4c4c380d174cc2f9281b34f89e and fixed in 7.3-rc1 with commit 77933e22adfe813be2bd10be08d6e950103c3967 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-2026-89651 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/ceph/mds_client.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/dc5c7dffda92ef372fa587c444a1c537373df824 https://git.kernel.org/stable/c/c37db86d2b5e9b57001ccae7e7a727e95a4f9c02 https://git.kernel.org/stable/c/5f892c767b30e4fb0c744c59f9235c717383d2cd https://git.kernel.org/stable/c/77933e22adfe813be2bd10be08d6e950103c3967