diff options
| author |   Willem de Bruijn <willemb@google.com> | 2017-02-03 18:20:49 -0500 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-02-06 22:41:27 -0500 |
| commit | 837585a5375c38d40361cfe64e6fd11e1addb936 (patch) | |
| tree | 9acf1060c120551d70a9b31fc8075bf1d834eb98 /drivers/net/macvtap.c | |
| parent | tun: read vnet_hdr_sz once (diff) | |
| download | linux-dev-837585a5375c38d40361cfe64e6fd11e1addb936.tar.xz linux-dev-837585a5375c38d40361cfe64e6fd11e1addb936.zip | |
macvtap: read vnet_hdr_size once
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@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/macvtap.c')
| -rw-r--r-- | drivers/net/macvtap.c | 4 |
1 files 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; |