From patchwork Fri Feb 3 23:20:49 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Willem de Bruijn X-Patchwork-Id: 723965 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3vFXt43zvcz9s76 for ; Sat, 4 Feb 2017 10:21:00 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="ZBIE2F24"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752896AbdBCXU7 (ORCPT ); Fri, 3 Feb 2017 18:20:59 -0500 Received: from mail-qt0-f195.google.com ([209.85.216.195]:35835 "EHLO mail-qt0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752856AbdBCXU5 (ORCPT ); Fri, 3 Feb 2017 18:20:57 -0500 Received: by mail-qt0-f195.google.com with SMTP id s58so7660926qtc.2 for ; Fri, 03 Feb 2017 15:20:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=HMVfAIoUQw8fkSdD6VCM+Qqp/LlAI/0Ec0sZ84VdYLU=; b=ZBIE2F24hBWsxNKDCiUEgWFndYVnJFQjkk9QbPKu85lNxibdtwiOhR8Jhw5oD0b3QJ P5BSs9Zztdw1pMrbMJ+JwGtRBvPFQ9IGUaQkbH36LKUV8AjGuY1RaEkZ6ceTkpCGIgi1 vIRuK/zu8Yd/EnzAwzk9eHbnk5vHNzkCgNVTw3MLG6pIwYDthdaReX5uKKhxkK5huqcN CQse6ZjfrZC85A80ekshOI5hMT7xvDeI+QQFJvi0yW2cVCKuyNa68Scr7dROQeisp/2U M2hW37/fLSSEmoBrdt9pht89J1xFRirZUrFGgFBygTywVQfJSz2W9LoDSSo1fQJQ+/nO myfQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=HMVfAIoUQw8fkSdD6VCM+Qqp/LlAI/0Ec0sZ84VdYLU=; b=J8ck7nEk+glaRYp6edXE2IJr4L4b5yjW5sRDlQa9pR7D8GFLTnSl7HMBTt7QcSTVlp MW+yg6jV2V7omkrKxZ4wbFuTVoQmDVqjqa3sXRQhBTohsfxI0b461oZZIdd1XtpQkNXJ gJzHlULQAam+boyY7PdAa7nq/HCe8reGY5yLrkNDLdYotoYdkSmyYVLfScnbVDzlbahD 7olwk9Lr33/kP6x9D19i9It2mGTl0AODMa9+CdAzhqH8C6JsAJCANkS4/DDV6BoxUXzi wFA8XIVetOg9r0EpcCwK4LR1wYI15nmE4JgQrqJs4NaJIN9CRLE3Uo+YPpYfecBx/DJ4 4YMQ== X-Gm-Message-State: AIkVDXJDWxa/KncbOjBlHvOMJgjZKVZag0/A4e2vDZOTl+4HGrry+6Tqrn8liW1koYe2+Q== X-Received: by 10.237.38.3 with SMTP id z3mr15205629qtc.22.1486164056917; Fri, 03 Feb 2017 15:20:56 -0800 (PST) Received: from willemb1.nyc.corp.google.com ([100.101.212.14]) by smtp.gmail.com with ESMTPSA id z8sm25814009qkz.42.2017.02.03.15.20.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 03 Feb 2017 15:20:55 -0800 (PST) From: Willem de Bruijn To: netdev@vger.kernel.org Cc: davem@davemloft.net, Willem de Bruijn Subject: [PATCH net 2/2] macvtap: read vnet_hdr_size once Date: Fri, 3 Feb 2017 18:20:49 -0500 Message-Id: <20170203232049.38982-3-willemdebruijn.kernel@gmail.com> X-Mailer: git-send-email 2.11.0.483.g087da7b7c-goog In-Reply-To: <20170203232049.38982-1-willemdebruijn.kernel@gmail.com> References: <20170203232049.38982-1-willemdebruijn.kernel@gmail.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Willem de Bruijn When IFF_VNET_HDR is enabled, a virtio_net header must precede data. Data length is verified to be greater than or equal to expected header length tun->vnet_hdr_sz before copying. Macvtap functions read the value once, but unless READ_ONCE is used, the compiler may ignore this and read multiple times. Enforce a single read and locally cached value to avoid updates between test and use. Signed-off-by: Willem de Bruijn Suggested-by: Eric Dumazet Acked-by: Eric Dumazet --- drivers/net/macvtap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 402618565838..c27011bbe30c 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -681,7 +681,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, size_t linear; if (q->flags & IFF_VNET_HDR) { - vnet_hdr_len = q->vnet_hdr_sz; + vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); err = -EINVAL; if (len < vnet_hdr_len) @@ -820,7 +820,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q, if (q->flags & IFF_VNET_HDR) { struct virtio_net_hdr vnet_hdr; - vnet_hdr_len = q->vnet_hdr_sz; + vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz); if (iov_iter_count(iter) < vnet_hdr_len) return -EINVAL;