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 9a98454757897c84b3519ab020e762855eb8df7e..4289142e20b6f006fbf2c1f574cf7a094d66a526 100644 (file)
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -567,7 +567,7 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
        BrinOpaque *opaque;
        BlockNumber nblocks;
        BlockNumber heapBlk;
-       int                     totalpages = 0;
+       int64           totalpages = 0;
        FmgrInfo   *consistentFn;
        MemoryContext oldcxt;
        MemoryContext perRangeCxt;