postgres.git / summary / log / commit / refs

commit    39d24475c18059a2fe1de1d05352fd5eed6092b3
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Thu Oct 23 16:32:06 2025 +0000
First released in: 13.23, 14.20, 15.15, 16.11, 17.7, 18.1

    Fix off-by-one Asserts in FreePageBtreeInsertInternal/Leaf.
    
    These two functions expect there to be room to insert another item
    in the FreePageBtree's array, but their assertions were too weak
    to guarantee that.  This has little practical effect granting that
    the callers are not buggy, but it seems to be misleading late-model
    Coverity into complaining about possible array overrun.
    
    Author: Tom Lane <tgl@sss.pgh.pa.us>
    Discussion: https://postgr.es/m/799984.1761150474@sss.pgh.pa.us
    Backpatch-through: 13


 src/backend/utils/mmgr/freepage.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/backend/utils/mmgr/freepage.c b/src/backend/utils/mmgr/freepage.c
index 29428025677..78f6b17a264 100644
--- a/src/backend/utils/mmgr/freepage.c
+++ b/src/backend/utils/mmgr/freepage.c
@@ -894,14 +894,14 @@ FreePageBtreeGetRecycled(FreePageManager *fpm)
 }
 
 /*
- * Insert an item into an internal page.
+ * Insert an item into an internal page (there must be room).
  */
 static void
 FreePageBtreeInsertInternal(char *base, FreePageBtree *btp, Size index,
 							Size first_page, FreePageBtree *child)
 {
 	Assert(btp->hdr.magic == FREE_PAGE_INTERNAL_MAGIC);
-	Assert(btp->hdr.nused <= FPM_ITEMS_PER_INTERNAL_PAGE);
+	Assert(btp->hdr.nused < FPM_ITEMS_PER_INTERNAL_PAGE);
 	Assert(index <= btp->hdr.nused);
 	memmove(&btp->u.internal_key[index + 1], &btp->u.internal_key[index],
 			sizeof(FreePageBtreeInternalKey) * (btp->hdr.nused - index));
@@ -911,14 +911,14 @@ FreePageBtreeInsertInternal(char *base, FreePageBtree *btp, Size index,
 }
 
 /*
- * Insert an item into a leaf page.
+ * Insert an item into a leaf page (there must be room).
  */
 static void
 FreePageBtreeInsertLeaf(FreePageBtree *btp, Size index, Size first_page,
 						Size npages)
 {
 	Assert(btp->hdr.magic == FREE_PAGE_LEAF_MAGIC);
-	Assert(btp->hdr.nused <= FPM_ITEMS_PER_LEAF_PAGE);
+	Assert(btp->hdr.nused < FPM_ITEMS_PER_LEAF_PAGE);
 	Assert(index <= btp->hdr.nused);
 	memmove(&btp->u.leaf_key[index + 1], &btp->u.leaf_key[index],
 			sizeof(FreePageBtreeLeafKey) * (btp->hdr.nused - index));


[parent: fbc41a145ae0]