From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 14 Aug 2025 02:15:23 +0000 (+1000)
Subject: Fix out of bounds in mmap WriteTo
X-Git-Tag: v1.59.0~2^2~13
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=c2ad0fc11fb5e4aed540c487324c7b37cc2237b7;p=btrtrc.git

Fix out of bounds in mmap WriteTo
---

diff --git a/storage/file-io-mmap.go b/storage/file-io-mmap.go
index ed181f3c..422c1c0a 100644
--- a/storage/file-io-mmap.go
+++ b/storage/file-io-mmap.go
@@ -186,7 +186,11 @@ type mmapFileHandle struct {
 }
 
 func (me *mmapFileHandle) WriteTo(w io.Writer) (n int64, err error) {
-	n1, err := w.Write(me.shared.f.m[me.pos:])
+	b := me.shared.f.m
+	if me.pos >= int64(len(b)) {
+		return
+	}
+	n1, err := w.Write(b[me.pos:])
 	n = int64(n1)
 	me.pos += n
 	return