Pull networking fixes from David Miller:
"A quick batch of bug fixes:
1) Fix build with IPV6 disabled, from Eric Dumazet.
2) Several more cases of caching SKB data pointers across calls to
pskb_may_pull(), thus referencing potentially free'd memory. From
Li RongQing.
3) DSA phy code tests operation presence improperly, instead of going:
if (x->ops->foo)
r = x->ops->foo(args);
it was going:
if (x->ops->foo(args))
r = x->ops->foo(args);
Fix from Andew Lunn"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
Net: DSA: Fix checking for get_phy_flags function
ipv6: fix a potential use after free in sit.c
ipv6: fix a potential use after free in ip6_offload.c
ipv4: fix a potential use after free in gre_offload.c
tcp: fix build error if IPv6 is not enabled
