From a09b915d97bc3f8c7d0794942544ea3911f9abc2 Mon Sep 17 00:00:00 2001
From: Bar Arnon <i3arnon@gmail.com>
Date: Sun, 15 Aug 2021 15:28:57 +0300
Subject: [PATCH] Validate CompressionLevel in BrotliStream ctor Fix #46595

---
 .../src/System/IO/Compression/BrotliUtils.cs                 | 2 +-
 .../src/System/IO/Compression/enc/BrotliStream.Compress.cs   | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libraries/System.IO.Compression.Brotli/src/System/IO/Compression/BrotliUtils.cs b/src/libraries/System.IO.Compression.Brotli/src/System/IO/Compression/BrotliUtils.cs
index d292a6725cb95..f865db32ed862 100644
--- a/src/libraries/System.IO.Compression.Brotli/src/System/IO/Compression/BrotliUtils.cs
+++ b/src/libraries/System.IO.Compression.Brotli/src/System/IO/Compression/BrotliUtils.cs
@@ -9,7 +9,7 @@ internal static partial class BrotliUtils
         public const int WindowBits_Default = 22;
         public const int WindowBits_Max = 24;
         public const int Quality_Min = 0;
-        public const int Quality_Default = 11;
+        public const int Quality_Default = 6;
         public const int Quality_Max = 11;
         public const int MaxInputSize = int.MaxValue - 515; // 515 is the max compressed extra bytes
 
diff --git a/src/libraries/System.IO.Compression.Brotli/src/System/IO/Compression/enc/BrotliStream.Compress.cs b/src/libraries/System.IO.Compression.Brotli/src/System/IO/Compression/enc/BrotliStream.Compress.cs
index efa17bc5f9cbb..5d3daa22c1229 100644
--- a/src/libraries/System.IO.Compression.Brotli/src/System/IO/Compression/enc/BrotliStream.Compress.cs
+++ b/src/libraries/System.IO.Compression.Brotli/src/System/IO/Compression/enc/BrotliStream.Compress.cs
@@ -23,6 +23,11 @@ public BrotliStream(Stream stream, CompressionLevel compressionLevel) : this(str
         /// <param name="leaveOpen"><see langword="true" /> to leave the stream open after disposing the <see cref="System.IO.Compression.BrotliStream" /> object; otherwise, <see langword="false" />.</param>
         public BrotliStream(Stream stream, CompressionLevel compressionLevel, bool leaveOpen) : this(stream, CompressionMode.Compress, leaveOpen)
         {
+            if ((int)compressionLevel is < BrotliUtils.Quality_Min or > BrotliUtils.Quality_Max)
+            {
+                throw new ArgumentException(SR.ArgumentOutOfRange_Enum, nameof(compressionLevel));
+            }
+
             _encoder.SetQuality(BrotliUtils.GetQualityFromCompressionLevel(compressionLevel));
         }