farsync: fix invalid memory accesses in fst_add_one() and fst_init_card()
farsync: fix invalid memory accesses in fst_add_one() and fst_init_card()

There are several issues in fst_add_one() and fst_init_card():
- invalid pointer dereference at card->ports[card->nports - 1] if
  register_hdlc_device() fails for the first port in fst_init_card();
- fst_card_array overflow at fst_card_array[no_of_cards_added]
  because there is no checks for array overflow;
- use after free because pointer to deallocated card is left in fst_card_array
  if something fails after fst_card_array[no_of_cards_added] = card;
- several leaks on failure paths in fst_add_one().

The patch fixes all the issues and makes code more readable.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <a9985f635ca4eb5d7c64df6d16c76aa9811509c5@ispras.ru>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs