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 4FB654BFE90 for ; Fri, 11 Sep 2026 20:00:41 +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=1789156855; cv=none; b=cNJuEzPSc6Zwbt90cWQvMlSAQQDpx9HAeQpfNUMoqCGdovpYCqpEsK/zaZD3mfRVkQUl/+zEjqKGpnPqmxJm18G8nhpNUWusPuC74/tptBmlD2VUkEgO5gb22DJspwmNXzKMYN2/kxFewh4XzdqwBcHqpx78Twoacxy7EAsU9gM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156855; c=relaxed/simple; bh=/Zu9NqXohoUVtBb2uuEmwjMmV2/3fodt9DBeY3Pbq+M=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=boSJ7FK2wGL90WVhrwwx1OcubWoqK27wzEjs7311L0D7XLxliTlAfRyjiyCEscAiAeFkTfl2lBFzA/nDa836b1YcnVysbFj5nXs+LtBVdIAAxE+8kIMfOI+L8rWF6T8b7v6Z4W62alcsoPX8xhpdnkjft1JBBsgGYtgdK89JLqI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=MuAiBjL4; 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="MuAiBjL4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4F581F000FF; Fri, 11 Sep 2026 20:00:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156838; bh=iZslyjuMo7b94TlIXIjqzedig8hkb2MhGjpT55h5lfY=; h=From:To:Cc:Subject:Date:Reply-To; b=MuAiBjL43xmINSXT2x5ZLDXLfTdogqNaDrEhC1HmdyUcHeFpSfgVyCTXwocBYa4U/ InO5TGIdFylc3Eovf4ufUe+PUUGu7h3OKw7PEP6qqF/Oe2A2aYmvHYQ95MHnJFaojk 8LiTWkpbddbeo5v6OAQWT2969waa5ywfjpE0UzgI= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89649: ceph: bound xattr value length in __build_xattrs() Date: Fri, 11 Sep 2026 21:45:38 +0200 Message-ID: <2026091143-CVE-2026-89649-9f1b@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=3745; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=4U4PzFbT7Z4LsuY3ReWOFQ0bKRqeL7NS3SlxOc0de8U=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIit2L5+6nqMw5FzCZ5c7f9L/nj08RaHGYnOKy8a+u w4yfZ87OmJZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAiPtwMs9mVmN/v6qnbIh55 rujLZrOKGvUb5QzzszLPLOItXtsZ6i8yrVbt3nrfrNitAA== 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 xattr value length in __build_xattrs() __build_xattrs() decodes the MDS-supplied xattr blob one attribute at a time. For each attribute it reads a 32-bit name length, advances past the name bytes, reads a 32-bit value length, records the value pointer, and advances past the value bytes. The two length fields are read with ceph_decode_32_safe(), but the value bytes themselves are advanced over with a bare "p += len" and no ceph_decode_need() check that "len" bytes remain in the blob. For every attribute except the last, the next iteration's ceph_decode_32_safe() on the following name length implicitly verifies that the previous value did not run past the blob end. The final attribute has no successor, so its decoded value length is never checked against the blob bounds. A malicious or compromised metadata server can set the last attribute's value length larger than the bytes actually present in the blob. The blob is a dedicated kvmalloc() allocation sized to the wire length (ceph_buffer_new() in ceph_fill_inode()). __set_xattr() records the oversized length in xattr->val_len verbatim, and a later getxattr(2) runs memcpy(value, xattr->val, xattr->val_len) into a user-supplied buffer, copying bytes past the end of the allocation back to user space. Impact: a malicious metadata server discloses adjacent kernel heap bytes to a local user via getxattr(2) on a CephFS file. Add the missing ceph_decode_need() so an out-of-bounds value length on the final attribute fails the decode and returns -EIO instead of being stored. The Linux kernel CVE team has assigned CVE-2026-89649 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.34 with commit 355da1eb7a1f91c276b991764e951bbcd8047599 and fixed in 6.12.109 with commit 38be2f3c41ecaba58bb92dc16603e09ba9fd64f1 Issue introduced in 2.6.34 with commit 355da1eb7a1f91c276b991764e951bbcd8047599 and fixed in 6.18.50 with commit 1dd356310b1660215f9a3626580bf8b363ef981e Issue introduced in 2.6.34 with commit 355da1eb7a1f91c276b991764e951bbcd8047599 and fixed in 7.2.4 with commit b12b3320c81fd72ab36388fb2445fec9c3038f10 Issue introduced in 2.6.34 with commit 355da1eb7a1f91c276b991764e951bbcd8047599 and fixed in 7.3-rc1 with commit 68d541754d6cd3bb98d1fd8314f57e5eb533557d 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-2026-89649 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/xattr.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/38be2f3c41ecaba58bb92dc16603e09ba9fd64f1 https://git.kernel.org/stable/c/1dd356310b1660215f9a3626580bf8b363ef981e https://git.kernel.org/stable/c/b12b3320c81fd72ab36388fb2445fec9c3038f10 https://git.kernel.org/stable/c/68d541754d6cd3bb98d1fd8314f57e5eb533557d