[Click] segmentation faukt with uniqueify()

[remi.clavier at orange-ftgroup.com]

Help needed !
 
In witch cases may the uniqueify() create a segmentation fault?
 
with this code, a seg fault occurs just after the uniqueify() line.
Packet *
SimpleQueueWithQoS::pull(int)
{
  Packet *p = deq();
  if (p && ( (size() >= _limitToMark ) && _active==1 ) || _active==2)
    p = action(p);
  return p;
}
 
Packet *
SimpleQueueWithQoS::action(Packet *p_in)
{
     click_chatter("before");
  WritablePacket *pp;
pp = p_in->uniqueify();
    click_chatter("after");
/* assert(p->has_network_header());
 

Thanks