netxen: fix off by one bug in netxen_release_tx_buffer()
Christoph Paasch found netxen could trigger a BUG in its dismantle
phase, in netxen_release_tx_buffer(), using full size TSO packets.
cmd_buf->frag_count includes the skb->data part, so the loop must
start at index 1 instead of 0, or else we can make an out
of bound access to cmd_buff->frag_array[MAX_SKB_FRAGS + 2]
Christoph provided the fixes in netxen_map_tx_skb() function.
In case of a dma mapping error, its better to clear the dma fields
so that we don't try to unmap them again in netxen_release_tx_buffer()
Reported-by: Christoph Paasch <christoph.paasch@uclouvain.be> Signed-off-by: Eric Dumazet <edumazet@google.com> Tested-by: Christoph Paasch <christoph.paasch@uclouvain.be> Cc: Sony Chacko <sony.chacko@qlogic.com> Cc: Rajesh Borundia <rajesh.borundia@qlogic.com> Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be> Signed-off-by: David S. Miller <davem@davemloft.net>