From: Peter Geoghegan <pg@bowt.ie>
Date: Thu, 6 Aug 2020 22:25:49 +0000 (-0700)
Subject: amcheck: Sanitize metapage's allequalimage field.
X-Git-Tag: REL_14_BETA1~1865
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c254d8d7b20bf629420b407a5451c3b32d1a7b0b;p=thirdparty%2Fpostgresql.git

amcheck: Sanitize metapage's allequalimage field.

This will be helpful if it ever proves necessary to revoke an opclass's
support for deduplication.

Backpatch: 13-, where nbtree deduplication was introduced.
---

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index c9f9e755dcc..384a8ac747e 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -305,8 +305,20 @@ bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
 					 errmsg("index \"%s\" lacks a main relation fork",
 							RelationGetRelationName(indrel))));
 
-		/* Check index, possibly against table it is an index on */
+		/* Extract metadata from metapage, and sanitize it in passing */
 		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+		if (allequalimage && !heapkeyspace)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+							RelationGetRelationName(indrel))));
+		if (allequalimage && !_bt_allequalimage(indrel, false))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+							RelationGetRelationName(indrel))));
+
+		/* Check index, possibly against table it is an index on */
 		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
 							 heapallindexed, rootdescend);
 	}