drop_monitor: Better sanitize notified packets
When working in 'packet' mode, drop monitor generates a notification
with a potentially truncated payload of the dropped packet. The payload
is copied from the MAC header, but I forgot to check that the MAC header
was set, so do it now.
Fixes:
ca30707dee2b ("drop_monitor: Add packet alert mode")
Fixes:
5e58109b1ea4 ("drop_monitor: Add support for packet alert mode for hardware drops")
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>