ovsdb: Fix potential leak when making diff of conditions.

OVN unit tests highlight this:

ERROR: LeakSanitizer: detected memory leaks
Direct leak of 1344 byte(s) in 1 object(s) allocated from:
    0 0x4db0b7 in calloc (ovsdb/ovsdb-server+0x4db0b7)
    1 0x5c2162 in xcalloc__ lib/util.c:124:31
    2 0x5c221c in xcalloc lib/util.c:161:12
    3 0x54afbc in ovsdb_condition_diff ovsdb/condition.c:527:21
    4 0x529da6 in ovsdb_monitor_table_condition_update ovsdb/monitor.c:824:5
    5 0x524fa4 in ovsdb_jsonrpc_parse_monitor_cond_change_request ovsdb/jsonrpc-server.c:1557:13
    6 0x5235c3 in ovsdb_jsonrpc_monitor_cond_change ovsdb/jsonrpc-server.c:1624:25
    7 0x5217f2 in ovsdb_jsonrpc_session_got_request ovsdb/jsonrpc-server.c:1034:17
    8 0x520ee6 in ovsdb_jsonrpc_session_run ovsdb/jsonrpc-server.c:572:17
    9 0x51ffbe in ovsdb_jsonrpc_session_run_all ovsdb/jsonrpc-server.c:602:21
    10 0x51fbcf in ovsdb_jsonrpc_server_run ovsdb/jsonrpc-server.c:417:9
    11 0x517550 in main_loop ovsdb/ovsdb-server.c:224:9
    12 0x512e80 in main ovsdb/ovsdb-server.c:507:5
    13 0x7f9ecf675b74 in __libc_start_main (/lib64/libc.so.6+0x27b74)

Fixes: ef1da75 ("ovsdb: condition: Process condition changes incrementally.")
Signed-off-by: Xavier Simonart <[email protected]>
Signed-off-by: Ilya Maximets <[email protected]>

ovsdb/condition.c

@@ -550,9 +550,14 @@ ovsdb_condition_diff(struct ovsdb_condition *diff,
                            &b->clauses[j]);
     }
 
-    diff->optimized = a->optimized && b->optimized;
-    if (diff->optimized) {
-        ovsdb_condition_optimize(diff);
+    if (diff->n_clauses) {
+        diff->optimized = a->optimized && b->optimized;
+        if (diff->optimized) {
+            ovsdb_condition_optimize(diff);
+        }
+    } else {
+        free(diff->clauses);
+        diff->clauses = NULL;
     }
 }
 

ovsdb/monitor.c

@@ -821,6 +821,7 @@ ovsdb_monitor_table_condition_update(
     ovsdb_condition_destroy(&mtc->new_condition);
     ovsdb_condition_clone(&mtc->new_condition, &cond);
     ovsdb_condition_destroy(&cond);
+    ovsdb_condition_destroy(&mtc->diff_condition);
     ovsdb_condition_diff(&mtc->diff_condition,
                          &mtc->old_condition, &mtc->new_condition);
     ovsdb_monitor_condition_add_columns(dbmon,

tests/ovsdb-monitor.at

@@ -586,6 +586,7 @@ row,action,name,number,_version
   [[]],
   [],
   [[[[["name","==","one"],["name","==","two"]]]],
+   [[[["name","==","two"],["name","==","one"]]]],
    [[[["name","==","one"]]]],
     [[[false]]],
     [[[true]]]])