From patchwork Thu Jun 18 21:02:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thadeu Lima de Souza Cascardo X-Patchwork-Id: 1312384 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=canonical.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49nvXq5nqPz9sR4 for ; Fri, 19 Jun 2020 07:03:07 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730297AbgFRVDD (ORCPT ); Thu, 18 Jun 2020 17:03:03 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:37776 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730008AbgFRVDC (ORCPT ); Thu, 18 Jun 2020 17:03:02 -0400 Received: from [189.110.235.168] (helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jm1gZ-00073w-PC; Thu, 18 Jun 2020 21:03:00 +0000 From: Thadeu Lima de Souza Cascardo To: Josef Bacik Cc: Jens Axboe , linux-block@vger.kernel.org, nbd@other.debian.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, cascardo@canonical.com Subject: [PATCH] nbd: allocate sufficient space for NBD_CMD_STATUS Date: Thu, 18 Jun 2020 18:02:40 -0300 Message-Id: <20200618210240.157566-2-cascardo@canonical.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200618210240.157566-1-cascardo@canonical.com> References: <20200618210240.157566-1-cascardo@canonical.com> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The nest attribute NBD_ATTR_DEVICE_LIST was not accounted for when allocating the message, resulting in -EMSGSIZE. As __alloc_skb aligns size requests to SMP_CACHE_BYTES and SLUB will end up allocating more than requested, this can hardly be reproduced on most setups. However, I managed to test this on a 32-bit x86 with 15 entries, by loading with nbds_max=15. It failed with -EMSGSIZE, while it worked with 14 or 16 entries. Signed-off-by: Thadeu Lima de Souza Cascardo --- drivers/block/nbd.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 43cff01a5a67..19551d8ca355 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -2265,6 +2265,7 @@ static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info) msg_size = nla_total_size(nla_attr_size(sizeof(u32)) + nla_attr_size(sizeof(u8))); msg_size *= (index == -1) ? nbd_total_devices : 1; + msg_size += nla_total_size(0); /* for NBD_ATTR_DEVICE_LIST */ reply = genlmsg_new(msg_size, GFP_KERNEL); if (!reply)