From a97c877f8684a9d20295a4e2871af1e846db9cc9 Mon Sep 17 00:00:00 2001
From: reesporte <reesedporter@gmail.com>
Date: Fri, 10 Jun 2022 11:00:02 -0500
Subject: [PATCH] avoid out-of-bounds panic in rbf

We've seen this happen with relatively large datasets with a relatively low
max-file-size. The solution we came up with was to increase the max-file-size
config option, which works, but we still don't want there to be a panic if we
hit this again.

see https://molecula.atlassian.net/browse/FB-1381 for more information.
---
 rbf/db.go | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/rbf/db.go b/rbf/db.go
index d13a0a84c..439d443c0 100644
--- a/rbf/db.go
+++ b/rbf/db.go
@@ -815,7 +815,15 @@ func (db *DB) writeDBPage(pgno uint32, page []byte) error {
 
 func (db *DB) readDBPage(pgno uint32) ([]byte, error) {
 	offset := int64(pgno) * PageSize
-	return db.data[offset : offset+PageSize], nil
+
+	// FB-1381
+	// Verify page number requested is within the current size of database.
+	bound := offset + PageSize
+	if sz := int64(len(db.data)); bound >= sz {
+		return nil, fmt.Errorf("rbf: page read out of bounds, pgno=%d upper-bound=%d file-size=%d", pgno, bound, sz)
+	}
+
+	return db.data[offset:bound], nil
 }
 
 // readWALPageByID reads a WAL page by WAL ID.