s?id=837585a5375c38d40361cfe64e6fd11e1addb936'>macvtap: read vnet_hdr_size once

Age	Commit message (Expand)	Author	Files	Lines
Willem de Bruijn	1	-2/+2
	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>
2017-02-06	tun: read vnet_hdr_sz once	Willem de Bruijn	1	-4/+6
	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. Read this value once and cache locally, as it can be updated between the test and use (TOCTOU). Signed-off-by: Willem de Bruijn <willemb@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> CC: Eric Dumazet <edumazet@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>