Fix potential integer overflow in bringetbitmap()

This function expects an "int64" as result and stores the number of
pages to add to the index scan bitmap as an "int", multiplying its final
result by 10.  For a relation large enough, this can theoretically
overflow if counting more than (INT32_MAX / 10) pages, knowing that the
number of pages is upper-bounded by MaxBlockNumber.

To avoid the overflow, this commit redefines "totalpages", used to
calculate the result, to be an "int64" rather than an "int".

Reported-by: Evgeniy Gorbanyov
Author: James Hunter
Discussion: https://www.postgresql.org/message-id/07704817-6fa0-460c-b1cf-cd18f7647041@basealt.ru
Backpatch-through: 13

diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 8c6ee96ca81cc0cbdf04e36f4aa444b9f39d3b2b..179b7dfa45665cde1de87fcb6bfd6cc33be48b0a 100644 (file)
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -361,7 +361,7 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
    BrinOpaque *opaque;
    BlockNumber nblocks;
    BlockNumber heapBlk;
-   int         totalpages = 0;
+   int64       totalpages = 0;
    FmgrInfo   *consistentFn;
    MemoryContext oldcxt;
    MemoryContext perRangeCxt;