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 335E837C92C; Thu, 30 Jul 2026 15:19:49 +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=1785424790; cv=none; b=kCB5Of7x2GZPaG0mlpDzCejpfIkWANVKYd+je2Yr4A3FJNE6qWCjzm6a9S24p5/5FXnCnTWEWvVj1DDc6nsTd8FLtnDJQ8Yr1HLL5foSE3zR3XiiOF/zPOBvMKdwgeoV9RCOR3q18wecOgkpkaS9YjCYY4EXqfRwsfIElCeVjEw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785424790; c=relaxed/simple; bh=VdO2U6518oH+fHSp6kSe09JaSkTYw1o7Hy6SibAyy9A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AS5hsd5a+g0k5oUTmE0Fr8w4XE5ogRr1gPCelRjPsdW+UeYWHT2xVGZ4sGiC84L5Q0VYVpjB+DWtlcIe/5I/f4WDyEVTzr6bTnjgsJnpimo6Mrreon22k/0AA7ghePva+90bK8sr8vZ6BPDjckP90/OXl8iwRkIqFkibLwhecUc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=E7Lw9nOw; 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="E7Lw9nOw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F4261F000E9; Thu, 30 Jul 2026 15:19:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785424789; bh=sSDaB8+H2oZikQ8oOmoJc8y3yb0yDIXRIts0F5yqQ9Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=E7Lw9nOwwPTxbuedzV/akvGgRq7rAWJltIhOPAi120wc1EFdzQaDCuG5Aq04fi9pj kqac3H2LC2suTHLSVBvoRmqgbvJQdeWHBh5JkxqORBbO09PN82Odh9N6bqEpUS52b+ pvjHPFFVI50f0cWq1sODNqblHpyDU2m7Q0+xYZjM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Raphael Zimmer , Ilya Dryomov Subject: [PATCH 6.18 518/675] libceph: Reject monmaps advertising zero monitors Date: Thu, 30 Jul 2026 16:14:08 +0200 Message-ID: <20260730141456.146084993@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Raphael Zimmer commit 40480eee361ed9676b3f844d532ac28b47251634 upstream. A message of type CEPH_MSG_MON_MAP contains a monmap that is sent from a monitor to the client. This monmap contains information about the existing monitors in the cluster. Currently, a monmap indicating that there are zero monitors in the cluster is treated as valid. However, it is impossible to have zero monitors in the cluster and still receive a valid monmap from a monitor. Therefore, such a monmap must be corrupted and should be treated as invalid. Furthermore, a monmap with a monitor count of zero can subsequently crash the client when attempting to open a session with a monitor in __open_session(). This happens because the "BUG_ON(monc->monmap->num_mon < 1)" assertion in pick_new_mon() is triggered. This patch extends a check in ceph_monmap_decode() to also reject arriving mon_maps with num_mon == 0 rather than only with num_mon > CEPH_MAX_MON. [ idryomov: drop "log output for unusual values of num_mon" part ] Cc: stable@vger.kernel.org Signed-off-by: Raphael Zimmer Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman --- net/ceph/mon_client.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ceph/mon_client.c +++ b/net/ceph/mon_client.c @@ -114,7 +114,7 @@ static struct ceph_monmap *ceph_monmap_d dout("%s fsid %pU epoch %u num_mon %u\n", __func__, &fsid, epoch, num_mon); - if (num_mon > CEPH_MAX_MON) + if (num_mon == 0 || num_mon > CEPH_MAX_MON) goto e_inval; monmap = kmalloc(struct_size(monmap, mon_inst, num_mon), GFP_NOIO);