Fix bogus CALLED_AS_TRIGGER() defenses.

tglsfdc · tglsfdc · commit 6dd9f3577925 · 2020-04-03T11:24:56.000-04:00
contrib/lo's lo_manage() thought it could use trigdata->tg_trigger->tgname in its error message about not being called as a trigger. That naturally led to a core dump. unique_key_recheck() figured it could Assert that fcinfo->context is a TriggerData node in advance of having checked that it's being called as a trigger. That's harmless in production builds, and perhaps not that easy to reach in any case, but it's logically wrong. The first of these per bug #16340 from William Crowell; the second from manual inspection of other CALLED_AS_TRIGGER call sites. Back-patch the lo.c change to all supported branches, the other to v10 where the thinko crept in. Discussion: https://postgr.es/m/16340-591c7449dc7c8c47@postgresql.org
diff --git a/contrib/lo/lo.c b/contrib/lo/lo.c
@@ -33,8 +33,7 @@ lo_manage(PG_FUNCTION_ARGS)
 	HeapTuple	trigtuple;		/* The original value of tuple	*/
 
 	if (!CALLED_AS_TRIGGER(fcinfo)) /* internal error */
-		elog(ERROR, "%s: not fired by trigger manager",
-			 trigdata->tg_trigger->tgname);
+		elog(ERROR, "lo_manage: not fired by trigger manager");
 
 	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event)) /* internal error */
 		elog(ERROR, "%s: must be fired for row",
diff --git a/src/backend/commands/constraint.c b/src/backend/commands/constraint.c
@@ -40,7 +40,7 @@
 Datum
 unique_key_recheck(PG_FUNCTION_ARGS)
 {
-	TriggerData *trigdata = castNode(TriggerData, fcinfo->context);
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
 	const char *funcname = "unique_key_recheck";
 	ItemPointerData checktid;
 	ItemPointerData tmptid;

Original file line number	Diff line number	Diff line change
`@@ -40,7 +40,7 @@`
`40`	`40`	`Datum`
`41`	`41`	`unique_key_recheck(PG_FUNCTION_ARGS)`
`42`	`42`	`{`
`43`		`- TriggerData *trigdata = castNode(TriggerData, fcinfo->context);`
	`43`	`+ TriggerData trigdata = (TriggerData ) fcinfo->context;`
`44`	`44`	`const char *funcname = "unique_key_recheck";`
`45`	`45`	`ItemPointerData checktid;`
`46`	`46`	`ItemPointerData tmptid;`