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commit    949e2e7c4f680ef86e93500ba4bee563ae4ce78e
Author:   Robert Haas <rhaas@postgresql.org>
Date:     Thu Mar 23 16:52:33 2023 +0000
First released in: 16.0

    amcheck: Fix a few bugs in new update chain validation.
    
    We shouldn't set successor[whatever] to an offset number that is less
    than FirstOffsetNumber or more than maxoff. We already avoided that
    for redirects, but not for CTID links. Allowing bad offset numbers
    into the successor[] array causes core dumps.
    
    We shouldn't use HeapTupleHeaderIsHotUpdated() because it checks
    stuff other than the status of the infomask2 bit HEAP_HOT_UPDATED.
    We only care about the status of that bit, not the other stuff
    that HeapTupleHeaderIsHotUpdated() checks. This mistake can cause
    verify_heapam() to report corruption when none is present.
    
    The first hunk of this patch was written by me. The other two were
    written by Andres Freund. This could probably do with more review
    before commit, but I'd like to try to get the buildfarm green again
    sooner rather than later.
    
    Discussion: http://postgr.es/m/20230322204552.s6cv3ybqkklhhybb@awork3.anarazel.de


 contrib/amcheck/verify_heapam.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/contrib/amcheck/verify_heapam.c b/contrib/amcheck/verify_heapam.c
index 663fb65dee6..1b8607c6cc8 100644
--- a/contrib/amcheck/verify_heapam.c
+++ b/contrib/amcheck/verify_heapam.c
@@ -543,7 +543,8 @@ verify_heapam(PG_FUNCTION_ARGS)
 			 */
 			nextblkno = ItemPointerGetBlockNumber(&(ctx.tuphdr)->t_ctid);
 			nextoffnum = ItemPointerGetOffsetNumber(&(ctx.tuphdr)->t_ctid);
-			if (nextblkno == ctx.blkno && nextoffnum != ctx.offnum)
+			if (nextblkno == ctx.blkno && nextoffnum != ctx.offnum &&
+				nextoffnum >= FirstOffsetNumber && nextoffnum <= maxoff)
 				successor[ctx.offnum] = nextoffnum;
 		}
 
@@ -665,15 +666,18 @@ verify_heapam(PG_FUNCTION_ARGS)
 			 * tuple should be marked as a heap-only tuple. Conversely, if the
 			 * current tuple isn't marked as HOT-updated, then the next tuple
 			 * shouldn't be marked as a heap-only tuple.
+			 *
+			 * NB: Can't use HeapTupleHeaderIsHotUpdated() as it checks if
+			 * hint bits indicate xmin/xmax aborted.
 			 */
-			if (!HeapTupleHeaderIsHotUpdated(curr_htup) &&
+			if (!(curr_htup->t_infomask2 & HEAP_HOT_UPDATED) &&
 				HeapTupleHeaderIsHeapOnly(next_htup))
 			{
 				report_corruption(&ctx,
 								  psprintf("non-heap-only update produced a heap-only tuple at offset %u",
 										   (unsigned) nextoffnum));
 			}
-			if (HeapTupleHeaderIsHotUpdated(curr_htup) &&
+			if ((curr_htup->t_infomask2 & HEAP_HOT_UPDATED) &&
 				!HeapTupleHeaderIsHeapOnly(next_htup))
 			{
 				report_corruption(&ctx,


[parent: dccef0f2f8f3]