ofp-parse: Fix typo in consistency check.

This check in parse_ofp_str__() attempted to detect inconsistencies
between matches and actions, or inconsistencies within the actions. In
this case, ofpacts_check() would effectively zero the "usable_protocols"
and return 0 (ie, OK). However, when checking the return parameter, it
checks the pointer rather than the value.

In practice, this seems to only come up for fields which are used
internally in OVS and not exposed for matching from the controller, like
tunnel flags or skb_priority.

Found by MIT STACK undefined behaviour checker.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

Author: joestringer

lib/ofp-parse.c

@@ -477,7 +477,7 @@ parse_ofp_str__(struct ofputil_flow_mod *fm, int command, char *string,
 
             err = ofpacts_check(ofpacts.data, ofpacts.size, &fm->match.flow,
                                 OFPP_MAX, fm->table_id, 255, usable_protocols);
-            if (!err && !usable_protocols) {
+            if (!err && !*usable_protocols) {
                 err = OFPERR_OFPBAC_MATCH_INCONSISTENT;
             }
             if (err) {

tests/ovs-ofctl.at

@@ -127,9 +127,9 @@ do
     echo "### test case: '$1' should have usable protocols '$2'"
     if test "$2" = none; then
       AT_CHECK([ovs-ofctl parse-flow "$1,actions=drop"], [1],
-               [usable protocols: none
+               [dnl
 ],
-               [ovs-ofctl: no usable protocol
+               [ovs-ofctl: actions are invalid with specified match (OFPBAC_MATCH_INCONSISTENT)
 ])
     else
       AT_CHECK_UNQUOTED([ovs-ofctl parse-flow "$1,actions=drop" | sed 1q], [0],
@@ -309,7 +309,7 @@ skb_priority=0x12341234,tcp,tp_src=123,actions=flood
 ]])
 
 AT_CHECK([ovs-ofctl parse-flows flows.txt
-], [1], [usable protocols: none
+], [1], [dnl
 ], [stderr])
 
 AT_CLEANUP