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 82F974F7CDC; Wed, 30 Sep 2026 15:40:35 +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=1790782838; cv=none; b=a2xClcYCg9NrmNIXeoIUfx3ZB6Up16M+Y9fLfs8YMbMBTyLhK1llGUArDyo8Y4vvFNuVjG3qO9lmCjCalEFQNXLCNityEIpwR6KzXRfMJZGDTuoXW6QQMW9yPySjxVVMyPm4QwTFDZ9KROZcZV3La/677LjHczwe8x30ecb5zFE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790782838; c=relaxed/simple; bh=1M3cVzCZ2zKlmOaifZ9Sl+ZDY36jVhMqvtsGCQQNbZY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TmYFA+P3XuXVkQf5uT4VEc8pmYSohmRwyS9+37WXQ1Rn6uyavRgzwnrOKvrzzffTrXbRxsTf5DhQ8flyBdc1LRtJJbfCAdVFeA9DF2fQKMJ45oJuR6ro55fwJ2t9NHdK9dqebHQDRQETNfdhFP2Swkdpf/Tsdqv0rPS37QSP4Nc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=UpFH1ZFG; 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="UpFH1ZFG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1FFE91F00893; Wed, 30 Sep 2026 15:40:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790782834; bh=Nn34/YRj3GXGJkDTT/0nXhy0UQEYHJ0sheva0+1htd0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UpFH1ZFGRpkvt0kypmhc76DnHQYv2Z7xwwuYvJ220mqQ7kj1fEDL8TklQK/bgswV1 g23qpqzA3LmIUCnLciYXQRlZHqSDa4J1NnFaep/P24DOjrFJkBArmAazjLMRV6FRz6 o3fUY/Iux958gAHwONZwNBv33fGfxVWlUEYhbkMY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Raphael Zimmer , Ilya Dryomov , Roman Demidov , Sasha Levin Subject: [PATCH 5.10 186/595] libceph: Reject monmaps advertising zero monitors Date: Wed, 30 Sep 2026 17:21:19 +0200 Message-ID: <20260930152351.741005878@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152347.700140858@linuxfoundation.org> References: <20260930152347.700140858@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 5.10-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 ] Signed-off-by: Raphael Zimmer Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov Signed-off-by: Roman Demidov Signed-off-by: Sasha Levin --- net/ceph/mon_client.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c index e1f01aef263e8..fac52fe7a5870 100644 --- a/net/ceph/mon_client.c +++ b/net/ceph/mon_client.c @@ -59,7 +59,7 @@ static struct ceph_monmap *ceph_monmap_decode(void *p, void *end) num_mon = ceph_decode_32(&p); - if (num_mon > CEPH_MAX_MON) + if (num_mon == 0 || num_mon > CEPH_MAX_MON) goto bad; m = kmalloc(struct_size(m, mon_inst, num_mon), GFP_NOFS); if (m == NULL) -- 2.53.0