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 91FB530C160; Fri, 4 Sep 2026 06:09:28 +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=1788502169; cv=none; b=a0sgXGW5bvpk2GMl0vgd4HfIDozOntEvTATuNABs9MB7gICqYhjeZDRgVDXU1d9H+ERx1UK/rrt3luX/FeSFBsOgWMS2tE51iW4NGBTDKyMTYUpR/c1ZIEoSOE4UPRllq39SePBPZF58D1Fq0vphBO80l+u/9hPzg2jesWNZiNs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788502169; c=relaxed/simple; bh=5USwzKAmzg6TNB5rSLosGer6yptjgzducncFBy25LJk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sVm/h1xI6fXaPnhHBkF3Trq0zRkVH2MKagih1mr74mHs4vDPufwNd/XbPY7Hipo1+jvx4FDBMNGZVf4QF5UeI0BbkJprx8RuanFyqhOc4oMR4giTUeaymjgFIZAb7OWJGjWgifBgT9Lm4IO2juKzJ16XZCSNmfnk+9nozV4TdCg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iwge1VZa; 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="iwge1VZa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA3681F00A3D; Fri, 4 Sep 2026 06:09:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788502168; bh=dlpafkn0MOE1MVydvMOTP2VfLehpVqskqvyk8J7gEmQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iwge1VZaKKZoidxUncgmP25OFlu8Vz8SNsXS83cYzYns1B/eZ1rjuVBzC9DmBAynK spvSDODM9Ynu+Am6o95k97hMjQs/nXi1+iaUUgzA+iohF8fmtRY6L2rjQ5wgEmVWLu Ss3BM4aVYFsPSovEPC2IdzckyYMAY+yBWSoqXXec= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Michael Bommarito , Viacheslav Dubeyko , Ilya Dryomov Subject: [PATCH 6.12 113/403] ceph: bound copied dentry name length in NFS export get_name Date: Fri, 4 Sep 2026 06:58:36 +0200 Message-ID: <20260904045737.397811031@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045734.806166532@linuxfoundation.org> References: <20260904045734.806166532@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Bommarito commit eff8013c5a8916613c742ae5a2cc341cb605c0ae upstream. ceph_get_name() copies the MDS-supplied name into the caller's NAME_MAX-sized buffer with memcpy(name, rinfo->dname, rinfo->dname_len) and then writes name[rinfo->dname_len] = 0, without checking dname_len against NAME_MAX. A malicious or buggy MDS that returns a LOOKUPNAME reply with dname_len > NAME_MAX overflows the buffer. __get_snap_name() copies rde->name / rde->name_len the same unchecked way. Impact: a malicious or compromised Ceph MDS overflows the NAME_MAX name buffer in a client's NFS-export get_name path, a slab out-of-bounds write reported by KASAN. Reachable when a CephFS mount is re-exported over NFS. Add ceph_export_copy_name(), which rejects lengths above NAME_MAX with -ENAMETOOLONG before the copy, and use it in both ceph_get_name() and __get_snap_name(). Cc: stable@vger.kernel.org Fixes: 19913b4eac4a ("ceph: add get_name() NFS export callback") Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Michael Bommarito Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman --- fs/ceph/export.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) --- a/fs/ceph/export.c +++ b/fs/ceph/export.c @@ -437,6 +437,16 @@ static struct dentry *ceph_fh_to_parent( return dentry; } +static int ceph_export_copy_name(char *name, const char *src, u32 len) +{ + if (len > NAME_MAX) + return -ENAMETOOLONG; + + memcpy(name, src, len); + name[len] = '\0'; + return 0; +} + static int __get_snap_name(struct dentry *parent, char *name, struct dentry *child) { @@ -502,9 +512,8 @@ static int __get_snap_name(struct dentry BUG_ON(!rde->inode.in); if (ceph_snap(inode) == le64_to_cpu(rde->inode.in->snapid)) { - memcpy(name, rde->name, rde->name_len); - name[rde->name_len] = '\0'; - err = 0; + err = ceph_export_copy_name(name, rde->name, + rde->name_len); goto out; } } @@ -569,8 +578,8 @@ static int ceph_get_name(struct dentry * rinfo = &req->r_reply_info; if (!IS_ENCRYPTED(dir)) { - memcpy(name, rinfo->dname, rinfo->dname_len); - name[rinfo->dname_len] = 0; + err = ceph_export_copy_name(name, rinfo->dname, + rinfo->dname_len); } else { struct fscrypt_str oname = FSTR_INIT(NULL, 0); struct ceph_fname fname = { .dir = dir, @@ -584,10 +593,9 @@ static int ceph_get_name(struct dentry * goto out; err = ceph_fname_to_usr(&fname, NULL, &oname, NULL); - if (!err) { - memcpy(name, oname.name, oname.len); - name[oname.len] = 0; - } + if (!err) + err = ceph_export_copy_name(name, oname.name, + oname.len); ceph_fname_free_buffer(dir, &oname); } out: