Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 15/32] macvtap: read vnet_hdr_size once | Date | Thu, 16 Feb 2017 09:54:51 -0800 |
| |
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Willem de Bruijn <willemb@google.com>
[ 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> --- 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;
| |