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 b5146c25dd0c9e9df38f50d10e7f7bc7749711ac..3cc1384916effb68a3c3985be2f1ed54ed5a451a 100644 (file)
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -422,7 +422,7 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
        BrinOpaque *opaque;
        BlockNumber nblocks;
        BlockNumber heapBlk;
-       int                     totalpages = 0;
+       int64           totalpages = 0;
        FmgrInfo   *consistentFn;
        MemoryContext oldcxt;
        MemoryContext perRangeCxt;