From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794063703; b=qxVfi4wh6OhLJM/o7x8wm5k/9QCN1cfcWatnPKiLZnUg3UYWdYDnZRqolLxJ6BBNVPl3 iNqFJV9EDeMMChlS/KpewOd6gsSlx5gzQeWzbj18mj1mVyXdYAMOnQdxt/VE5lqTMahI0 wU4uAh0dTSqKHlk1ED5UChYNA4OxtOq9+MEn/aW6aIx7YKsC/g2cPr8uhs7kyRZ7js5Cf Snjge6vZGe1pvRX8FD4x1yYDOb7sQI2DWXmIs0Y/dXXVu1Z/CM53JGI6HI4Ui2tBq4Ng8 AhSR8iE5JmmFUcJW8wVnggobM3Nji8dEIG0QlXdqx8L6O9FwJCICK16SH54yNK3LNBg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794063703; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=fwqGk4vEXWZi8o72VgL2OOlom47G1nuEpShL706TzQc=; b=AgJvDXm43PePivwIFebdY6+pQH4q5L4HF9zhjPbgDkmgCbnAi99U7CjwIC0GfDo+HHYu PGnvOB+yyBSPz1GAoTnIBw0IgXvwj9eGx4sGUkjSclc4galN8cazgNqqN6ivw/4yevRfz dMS2ZuHVG7lhIwoJEahj53gmp/eYPTCUQqua4x0WBoj1diHYgZ3BRRGN/FwlwHtvdGOjb iphm6HEC/BM0SDP0i1t7akcB574foFkpK6YDO+KWqDqUq0BEo7pTjMUO/cXwGyi0iQcJh sX6vcD99vekPDjdfKhSVVoMe1/WPB32w8SgNy/pL/sRJslz/fr+0XFZ+HvGN+PBY+Sg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=zOmypv10; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 19007606B8B7; Sat, 7 Nov 2026 15:01:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=zOmypv10 Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCC731F0089F; Sat, 7 Nov 2026 15:01:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794063703; bh=fwqGk4vEXWZi8o72VgL2OOlom47G1nuEpShL706TzQc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=zOmypv103wKCFQCWzXu25PKBio92p16wlCIBVDHIsGyU7qwcyu4v+s4ZHyRuuVq1M ozFaLplJR4+0X4QZrA1QSuFqlx2r4JoMDUMGKaxZlsUZsG0UBQIQjVyzdqpzrDoFCI DN0F3ce37QCrl8qMazQRiiGwt71xS/F/Df0w2tCA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, co+f8e3e01d8dda8689@bugs.sh, Xiang Mei , Alex Markuze , Ilya Dryomov , Sasha Levin Subject: [PATCH 6.18 768/869] ceph: reject mdsmaps that claim more than CEPH_MAX_MDS ranks Date: Sat, 7 Nov 2026 08:57:30 -0500 Message-ID: <20261107134918.758612810@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134852.069646174@linuxfoundation.org> References: <20261107134852.069646174@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei [ Upstream commit c1742590d2b2fc5fb217e1a9b520108f1fe282e5 ] check_new_map() sizes its export-target bitmap from CEPH_MAX_MDS but walks it with newmap->possible_max_rank, which comes straight off the wire: ceph_mdsmap_decode() sets it to max(m_num_active_mds, m_max_mds), then overwrites it with the size of the "in" set. Neither is bounded by CEPH_MAX_MDS, only by m_info allocating, so a monitor announcing more ranks than the bitmap holds makes test_bit() read past the end of targets[]. The clear_bit() loop above indexes the same bitmap, though it is additionally bounded by mdsc->max_sessions. The map arrives on the monitor connection, which is unauthenticated in legacy msgr mode. CEPH_MAX_MDS is a protocol constant from src/mds/mdstypes.h, and the reserved inode ranges in super.h are laid out one rank apart over that span, so a map claiming more ranks is corrupt. Reject it where the rank space is established rather than letting the count reach check_new_map(). BUG: KASAN: stack-out-of-bounds in check_new_map (fs/ceph/mds_client.c:5968) Read of size 8 at addr ffffc90000ac7798 by task kworker/1:2/127 Workqueue: ceph-msgr ceph_con_workfn Call Trace: dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120) print_report (mm/kasan/report.c:378 mm/kasan/report.c:482) kasan_report (mm/kasan/report.c:595) kasan_check_range (mm/kasan/generic.c:186 mm/kasan/generic.c:200) check_new_map (fs/ceph/mds_client.c:5968) ceph_mdsc_handle_mdsmap (fs/ceph/mds_client.c:7060) extra_mon_dispatch (fs/ceph/super.c:802) mon_dispatch (net/ceph/mon_client.c:1483) ceph_con_process_message (net/ceph/messenger.c:1424) ceph_con_v1_try_read (net/ceph/messenger_v1.c:1430) ceph_con_workfn (net/ceph/messenger.c:1576) process_one_work (kernel/workqueue.c:3396) worker_thread (kernel/workqueue.c:3479 kernel/workqueue.c:3560) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) ret_from_fork_asm (arch/x86/entry/entry_64.S:245) The buggy address belongs to stack of task kworker/1:2/127 and is located at offset 288 in frame: check_new_map (fs/ceph/mds_client.c:5846) This frame has 1 object: [32, 288) 'targets' Cc: stable@vger.kernel.org Fixes: d517b3983dd3 ("ceph: reconnect to the export targets on new mdsmaps") Reported-by: co+f8e3e01d8dda8689@bugs.sh Assisted-by: LLM Signed-off-by: Xiang Mei Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin --- fs/ceph/mdsmap.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c index c91c0e2e118ba..0fd578f0b2cd2 100644 --- a/fs/ceph/mdsmap.c +++ b/fs/ceph/mdsmap.c @@ -170,6 +170,10 @@ struct ceph_mdsmap *ceph_mdsmap_decode(struct ceph_mds_client *mdsc, void **p, * and the mds rank >= m_num_active_mds. */ m->possible_max_rank = max(m->m_num_active_mds, m->m_max_mds); + if (m->possible_max_rank > CEPH_MAX_MDS) { + err = -EIO; + goto corrupt; + } m->m_info = kcalloc(m->possible_max_rank, sizeof(*m->m_info), GFP_NOFS); if (!m->m_info) @@ -316,6 +320,10 @@ struct ceph_mdsmap *ceph_mdsmap_decode(struct ceph_mds_client *mdsc, void **p, { int num_laggy = 0; ceph_decode_32_safe(p, end, n, bad_ext); + if (n > CEPH_MAX_MDS) { + err = -EIO; + goto corrupt; + } ceph_decode_need(p, end, sizeof(u32) * n, bad_ext); for (i = 0; i < n; i++) { -- 2.53.0