From: Eric Dumazet <redacted>
Date: Wed, 02 May 2012 19:55:58 +0200

From: Eric Dumazet <edumazet@google.com>

Before stealing fragments or skb head, we must make sure skbs are not
cloned.

Alexander was worried about destination skb being cloned : In bridge
setups, a driver could be fooled if skb->data_len would not match skb
nr_frags.

If source skb is cloned, we must take references on pages instead.

Bug happened using tcpdump (if not using mmap())

Introduce kfree_skb_partial() helper to cleanup code.

Reported-by: Alexander Duyck <redacted>
Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied.