From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 20 Nov 2023 00:14:53 +0000 (+0900)
Subject: Prevent overflow for block number in buffile.c
X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=3650e7a3933166b40f7f9043bd91f45d3467c74d;p=users%2Frhaas%2Fpostgres.git

Prevent overflow for block number in buffile.c

As coded, the start block calculated by BufFileAppend() would overflow
once more than 16k files are used with a default block size.  This issue
existed before b1e5c9fa9ac4, but there's no reason not to be clean about
it.

Per report from Coverity, with a fix suggested by Tom Lane.
---

diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c
index 2ca3783233..73e9aca9d2 100644
--- a/src/backend/storage/file/buffile.c
+++ b/src/backend/storage/file/buffile.c
@@ -904,7 +904,7 @@ BufFileSize(BufFile *file)
 int64
 BufFileAppend(BufFile *target, BufFile *source)
 {
-	int64		startBlock = target->numFiles * BUFFILE_SEG_SIZE;
+	int64		startBlock = (int64) target->numFiles * BUFFILE_SEG_SIZE;
 	int			newNumFiles = target->numFiles + source->numFiles;
 	int			i;