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 908774AF9DF for ; Thu, 3 Sep 2026 13:46:30 +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=1788443195; cv=none; b=pHsIlP6Xja37HteqT3HInCebKAxNj9e47CBB6ZwxCgtvmFpruBdTDokKCUTerPheKJZpxbgt2/CP7I5kpHPvDe7R2GzOPciPvCKRHVfhLtagL8ChHXHekHRUlsMZZLaOlElKQ8sQm+qVqp/62Oy7JmW4mM3Rey1cWwlTWKl85S4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788443195; c=relaxed/simple; bh=FENan/nchL6s8C2CgXYNhIqn8ximuEzj9PiyNz7/iv0=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=vFEL/SLdl87OIE6EEWgaKIvN2HbXErhCkBM7GVSJ4xB8xennBlW1UZLP6WTgzWVlbfr0TzIP4NUiIYPs9mvyZhQw13Q+UivuTCGmhgwv0ZPZTot5vKrneGmILtIpcRCNZOqwJU7AVJvcE1p5CyE8JaVp0IHqcDERjXrAKc6V1o4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yWzpEZrY; 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="yWzpEZrY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04D5B1F00ACA; Thu, 3 Sep 2026 13:46:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788443188; bh=rtZ8gcEAlYsgACkeQ8kffD31Cl5OY4syeRnhYPXFfBE=; h=Subject:To:Cc:From:Date; b=yWzpEZrY0+BO3cNg5mLOKxaiwh1xmc6dnhFQ8ZZdwRGPxyYneAzZsbsX/WpHB12xM dOm8j1xgCp+1tT39e8nRtoVAz5U/zu4CmnjAHZeckEAPPl+1s+BsQWWFnZ2vFwLlEl OPPXFbb0rnHtoFPCtUok37yN74uFKwolJoGCLjgY= Subject: FAILED: patch "[PATCH] ceph: bound copied dentry name length in NFS export get_name" failed to apply to 6.1-stable tree To: michael.bommarito@gmail.com,idryomov@gmail.com,slava@dubeyko.com Cc: From: Date: Thu, 03 Sep 2026 15:22:17 +0200 Message-ID: <2026090317-designing-flagstone-ad4f@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x eff8013c5a8916613c742ae5a2cc341cb605c0ae # git commit -s git send-email --to '' --in-reply-to '2026090317-designing-flagstone-ad4f@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From eff8013c5a8916613c742ae5a2cc341cb605c0ae Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Sat, 11 Jul 2026 11:07:05 -0400 Subject: [PATCH] ceph: bound copied dentry name length in NFS export get_name 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 diff --git a/fs/ceph/export.c b/fs/ceph/export.c index b2f2af104679..debb9634b9e3 100644 --- a/fs/ceph/export.c +++ b/fs/ceph/export.c @@ -442,6 +442,16 @@ static struct dentry *ceph_fh_to_parent(struct super_block *sb, 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) { @@ -513,9 +523,8 @@ static int __get_snap_name(struct dentry *parent, char *name, 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; } } @@ -580,8 +589,8 @@ static int ceph_get_name(struct dentry *parent, char *name, 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, @@ -595,10 +604,9 @@ static int ceph_get_name(struct dentry *parent, char *name, 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: