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 a257903991d4d1916d77872648c674cce6041e9c..d69d0fdf09a143717fd96ad70cfa00ac6742acec 100644 (file)
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -363,7 +363,7 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
    BrinOpaque *opaque;
    BlockNumber nblocks;
    BlockNumber heapBlk;
-   int         totalpages = 0;
+   int64       totalpages = 0;
    FmgrInfo   *consistentFn;
    MemoryContext oldcxt;
    MemoryContext perRangeCxt;