From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:33544 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751516AbdBOBED (ORCPT ); Tue, 14 Feb 2017 20:04:03 -0500 Subject: Patch "macvtap: read vnet_hdr_size once" has been added to the 4.9-stable tree To: willemb@google.com, davem@davemloft.net, edumazet@google.com, gregkh@linuxfoundation.org Cc: , From: Date: Tue, 14 Feb 2017 17:04:01 -0800 Message-ID: <148712064124838@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled macvtap: read vnet_hdr_size once to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: macvtap-read-vnet_hdr_size-once.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo@baz Tue Feb 14 17:03:08 PST 2017 From: Willem de Bruijn Date: Fri, 3 Feb 2017 18:20:49 -0500 Subject: macvtap: read vnet_hdr_size once From: Willem de Bruijn [ Upstream commit 837585a5375c38d40361cfe64e6fd11e1addb936 ] 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/macvtap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -682,7 +682,7 @@ static ssize_t macvtap_get_user(struct m ssize_t n; 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) @@ -822,7 +822,7 @@ static ssize_t macvtap_put_user(struct m 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; Patches currently in stable-queue which might be from willemb@google.com are queue-4.9/packet-round-up-linear-to-header-len.patch queue-4.9/tun-read-vnet_hdr_sz-once.patch queue-4.9/ipv6-fix-ip6_tnl_parse_tlv_enc_lim.patch queue-4.9/net-introduce-device-min_header_len.patch queue-4.9/macvtap-read-vnet_hdr_size-once.patch