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 <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Feb 14 17:03:08 PST 2017
From: Willem de Bruijn <willemb@xxxxxxxxxx>
Date: Fri, 3 Feb 2017 18:20:49 -0500
Subject: macvtap: read vnet_hdr_size once
From: Willem de Bruijn <willemb@xxxxxxxxxx>
[ 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 <willemb@xxxxxxxxxx>
Suggested-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxx 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