MAXALIGN the target address where we store flattened value.

Amit Kapila · Amit Kapila · commit 9bc9f72b28fe · 2018-10-03T09:15:03.000+05:30
The API (EOH_flatten_into) that flattens the expanded value representation expects the target address to be maxaligned. All it's usage adhere to that principle except when serializing datums for parallel query. Fix that usage. Diagnosed-by: Tom Lane Author: Tom Lane and Amit Kapila Backpatch-through: 9.6 Discussion: https://postgr.es/m/11629.1536550032@sss.pgh.pa.us
diff --git a/src/backend/utils/adt/datum.c b/src/backend/utils/adt/datum.c
@@ -338,8 +338,19 @@ datumSerialize(Datum value, bool isnull, bool typByVal, int typLen,
 		}
 		else if (eoh)
 		{
-			EOH_flatten_into(eoh, (void *) *start_address, header);
+			char	   *tmp;
+
+			/*
+			 * EOH_flatten_into expects the target address to be maxaligned,
+			 * so we can't store directly to *start_address.
+			 */
+			tmp = (char *) palloc(header);
+			EOH_flatten_into(eoh, (void *) tmp, header);
+			memcpy(*start_address, tmp, header);
 			*start_address += header;
+
+			/* be tidy. */
+			pfree(tmp);
 		}
 		else
 		{

Original file line number	Diff line number	Diff line change
`@@ -338,8 +338,19 @@ datumSerialize(Datum value, bool isnull, bool typByVal, int typLen,`
`338`	`338`	`}`
`339`	`339`	`else if (eoh)`
`340`	`340`	`{`
`341`		`- EOH_flatten_into(eoh, (void ) start_address, header);`
	`341`	`+ char *tmp;`
	`342`	`+`
	`343`	`+ /*`
	`344`	`+ * EOH_flatten_into expects the target address to be maxaligned,`
	`345`	`+ * so we can't store directly to *start_address.`
	`346`	`+ */`
	`347`	`+ tmp = (char *) palloc(header);`
	`348`	`+ EOH_flatten_into(eoh, (void *) tmp, header);`
	`349`	`+ memcpy(*start_address, tmp, header);`
`342`	`350`	`*start_address += header;`
	`351`	`+`
	`352`	`+ /* be tidy. */`
	`353`	`+ pfree(tmp);`
`343`	`354`	`}`
`344`	`355`	`else`
`345`	`356`	`{`