diff options
| author | Willem de Bruijn <willemb@google.com> | 2017-02-03 18:20:49 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-02-18 15:11:42 +0100 |
| commit | b90cb484c068b3fd30aee322506d38bcc2f43838 (patch) | |
| tree | 4b3ae45d4266d6c2653a57d81f105da9a66bd2ce /drivers | |
| parent | 26989c9d9904e3626443336bcefab0b6e7077d99 (diff) | |
macvtap: read vnet_hdr_size once
[ 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@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -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 6f38daf2d978..adea6f5a4d71 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -682,7 +682,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *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 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; |