BugLink: https://bugs.launchpad.net/bugs/1792419

commit ac74f87c upstream.

This patch fixes patch add handling to take care tail and headroom for
single 6lowpan frames. We need to be sure we have a skb with the right
head and tailroom for single frames. This patch do it by using
skb_copy_expand() if head and tailroom is not enough allocated by upper
layer.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=195059Reported-by: David Palma <david.palma@ntnu.no>
Reported-by: Rabi Narayan Sahoo <rabinarayans0828@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>