NETFILTER: nfnetlink_queue: fix SKB_LINEAR_ASSERT when mangling packet data

NETFILTER: nfnetlink_queue: fix SKB_LINEAR_ASSERT when mangling packet data

Upstream commit e2b58a67:

As reported by Tomas Simonaitis <tomas.simonaitis@gmail.com>, inserting new
data in skbs queued over {ip,ip6,nfnetlink}_queue triggers a SKB_LINEAR_ASSERT
in skb_put().

Going back through the git history, it seems this bug is present since at
least 2.6.12-rc2, probably even since the removal of skb_linearize() for
netfilter.

Linearize non-linear skbs through skb_copy_expand() when enlarging them.
Tested by Thomas, fixes bugzilla #9933.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>