From e6ff9aac0d8d85a595c56be4ec3058f1af0314c6 Mon Sep 17 00:00:00 2001
From: ucwong <ucwong@126.com>
Date: Wed, 14 Jan 2026 18:41:26 +0800
Subject: [PATCH] fix limitedBuffer.Write to properly enforce size limit

---
 rpc/handler.go | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/rpc/handler.go b/rpc/handler.go
index 3dedabb98a..8384a0bb55 100644
--- a/rpc/handler.go
+++ b/rpc/handler.go
@@ -612,8 +612,11 @@ type limitedBuffer struct {
 }
 
 func (buf *limitedBuffer) Write(data []byte) (int, error) {
-	avail := max(buf.limit, len(buf.output))
-	if len(data) < avail {
+	avail := buf.limit - len(buf.output)
+	if avail <= 0 {
+		return 0, errTruncatedOutput
+	}
+	if len(data) <= avail {
 		buf.output = append(buf.output, data...)
 		return len(data), nil
 	}