Fix ubsan warning.

During configuration parsing there was
`array-index-out-of-bounds` warning, because
we set value in the loop even if index out
of range.

Author: EvgeniiMekhanik

fw/cfg.h

@@ -183,13 +183,16 @@ typedef struct {
  */
 #define TFW_CFG_ENTRY_FOR_EACH_ATTR(e, idx, k, v)	\
 	for ((idx) = 0, (k) = (e)->attrs[0].key, (v) = (e)->attrs[0].val; \
-	     (idx++) < (e)->attr_n; \
-	     (k) = (e)->attrs[(idx)].key, (v) = (e)->attrs[(idx)].val)
+	     (idx) < (e)->attr_n; \
+	     (idx)++,  \
+	     (k) = (idx < (e)->attr_n ? (e)->attrs[(idx)].key : NULL), \
+	     (v) = (idx < (e)->attr_n ? (e)->attrs[(idx)].val : NULL))
 
 #define TFW_CFG_ENTRY_FOR_EACH_VAL(e, idx, v)	\
 	for ((idx) = 0, (v) = (e)->vals[0];	\
 	     (idx) < (e)->val_n;		\
-	     (v) = (e)->vals[++(idx)])
+	     (idx)++,				\
+	     (v) = (idx < (e)->val_n ? (e)->vals[(idx)] : NULL))
 
 #define TFW_CFG_CHECK_NO_ATTRS(spec, entry)				\
 	if ((entry)->attr_n) {						\