From feed9c97a9a97be020782cfed1d1dafbfe10b884 Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Fri, 21 Jun 2024 06:59:02 -0700
Subject: [PATCH] Avoid char[] allocation in AltSvcHeaderParser (#103764)

---
 .../src/System/Net/Http/Headers/AltSvcHeaderParser.cs        | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libraries/System.Net.Http/src/System/Net/Http/Headers/AltSvcHeaderParser.cs b/src/libraries/System.Net.Http/src/System/Net/Http/Headers/AltSvcHeaderParser.cs
index e4e6f77e22863b..5d75a68d72f2b2 100644
--- a/src/libraries/System.Net.Http/src/System/Net/Http/Headers/AltSvcHeaderParser.cs
+++ b/src/libraries/System.Net.Http/src/System/Net/Http/Headers/AltSvcHeaderParser.cs
@@ -265,7 +265,9 @@ private static bool TryReadUnknownPercentEncodedAlpnProtocolName(ReadOnlySpan<ch
                 return true;
             }
 
-            var builder = new ValueStringBuilder(value.Length <= 128 ? stackalloc char[128] : new char[value.Length]);
+            var builder = value.Length <= 128 ?
+                new ValueStringBuilder(stackalloc char[128]) :
+                new ValueStringBuilder(value.Length);
 
             do
             {
@@ -276,6 +278,7 @@ private static bool TryReadUnknownPercentEncodedAlpnProtocolName(ReadOnlySpan<ch
 
                 if ((value.Length - idx) < 3 || !TryReadAlpnHexDigit(value[1], out int hi) || !TryReadAlpnHexDigit(value[2], out int lo))
                 {
+                    builder.Dispose();
                     result = null;
                     return false;
                 }