IB/rxe: Add a runtime check in alloc_index()

Since index values equal to or above 'range' can trigger memory
corruption, complain if index >= range.
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: NAndrew Boyer <andrew.boyer@dell.com>
Cc: Moni Shoua <monis@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rxe/rxe_pool.c

@@ -266,6 +266,7 @@ static u32 alloc_index(struct rxe_pool *pool)
 	if (index >= range)
 		index = find_first_zero_bit(pool->table, range);
 
+	WARN_ON_ONCE(index >= range);
 	set_bit(index, pool->table);
 	pool->last = index;
 	return index + pool->min_index;