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 a38ff1b4fd23da427443c9faea9ab5f5acf63fed..d3b5f349a24ac738c5f75f644c07a55b20dc0ec0 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;