[release/2.1] Fix ReadOnlySequence created out of sliced Memory owned by MemoryManager

pkg/Microsoft.Private.PackageBaseline/packageIndex.json

@@ -2510,9 +2510,10 @@
         "4.5.1",
         "4.5.2",
         "4.5.3",
-        "4.5.4"
+        "4.5.4",
+        "4.5.5"
       ],
-      "BaselineVersion": "4.5.4",
+      "BaselineVersion": "4.5.5",
       "InboxOn": {
         "netcoreapp2.1": "4.1.0.0"
       },

src/System.Memory/dir.props

@@ -2,7 +2,7 @@
 <Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="..\dir.props" />
   <PropertyGroup>
-    <AssemblyVersion>4.0.1.1</AssemblyVersion>
+    <AssemblyVersion>4.0.1.2</AssemblyVersion>
     <!-- System.Memory has forwarded types into the runtime on netcoreapp/uap
          It must win over assemblies versioned at 4.0.* -->
     <AssemblyVersion Condition="'$(TargetGroup)' == 'netcoreapp' OR '$(TargetGroup)' == 'uap' ">4.1.0.0</AssemblyVersion>

src/System.Memory/pkg/System.Memory.pkgproj

@@ -2,7 +2,7 @@
 <Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
   <PropertyGroup>
-    <PackageVersion>4.5.4</PackageVersion>
+    <PackageVersion>4.5.5</PackageVersion>
   </PropertyGroup>
   <ItemGroup>
     <PackageIndex Include="$(ProjectDir)\pkg\baseline\packageBaseline.1.1.json" />

src/System.Memory/src/System/Buffers/ReadOnlySequence.cs

@@ -130,7 +130,7 @@ public ReadOnlySequence(ReadOnlyMemory<T> memory)
             if (MemoryMarshal.TryGetMemoryManager(memory, out MemoryManager<T> manager, out int index, out int length))
             {
                 _sequenceStart = new SequencePosition(manager, ReadOnlySequence.MemoryManagerToSequenceStart(index));
-                _sequenceEnd = new SequencePosition(manager, ReadOnlySequence.MemoryManagerToSequenceEnd(length));
+                _sequenceEnd = new SequencePosition(manager, ReadOnlySequence.MemoryManagerToSequenceEnd(index + length));
             }
             else if (MemoryMarshal.TryGetArray(memory, out ArraySegment<T> segment))
             {

src/System.Memory/tests/ReadOnlyBuffer/ReadOnlySequenceFactory.byte.cs

@@ -5,13 +5,16 @@
 using System.Buffers;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 
 namespace System.Memory.Tests
 {
     public abstract class ReadOnlySequenceFactory<T>
     {
         public static ReadOnlySequenceFactory<T> ArrayFactory { get; } = new ArrayTestSequenceFactory();
         public static ReadOnlySequenceFactory<T> MemoryFactory { get; } = new MemoryTestSequenceFactory();
+        public static ReadOnlySequenceFactory<T> MemoryManagerFactory { get; } = new MemoryManagerTestSequenceFactory();
         public static ReadOnlySequenceFactory<T> SingleSegmentFactory { get; } = new SingleSegmentTestSequenceFactory();
         public static ReadOnlySequenceFactory<T> SegmentPerItemFactory { get; } = new BytePerSegmentTestSequenceFactory();
         public static ReadOnlySequenceFactory<T> SplitInThree { get; } = new SplitInThreeSegmentsTestSequenceFactory();
@@ -102,6 +105,49 @@ public override ReadOnlySequence<T> CreateWithContent(T[] data)
             }
         }
 
+        internal class MemoryManagerTestSequenceFactory : ReadOnlySequenceFactory<T>
+        {
+            public override ReadOnlySequence<T> CreateOfSize(int size)
+            {
+#if DEBUG
+                return new ReadOnlySequence<T>(new CustomMemoryManager(size + 1).Memory.Slice(1));
+#else
+                return new ReadOnlySequence<T>(new CustomMemoryManager(size).Memory);
+#endif
+            }
+
+            public override ReadOnlySequence<T> CreateWithContent(T[] data)
+            {
+                return new ReadOnlySequence<T>(new CustomMemoryManager(data).Memory);
+            }
+
+            private unsafe class CustomMemoryManager : MemoryManager<T>
+            {
+                private readonly T[] _buffer;
+
+                public CustomMemoryManager(int size) => _buffer = new T[size];
+
+                public CustomMemoryManager(T[] content) => _buffer = content;
+
+                public unsafe override Span<T> GetSpan() => _buffer;
+
+                public override unsafe MemoryHandle Pin(int elementIndex = 0)
+                {
+                    if ((uint)elementIndex > (uint)_buffer.Length)
+                    {
+                        throw new ArgumentOutOfRangeException(nameof(elementIndex));
+                    }
+
+                    var handle = GCHandle.Alloc(_buffer, GCHandleType.Pinned);
+                    return new MemoryHandle(Unsafe.Add<T>((void*)handle.AddrOfPinnedObject(), elementIndex), handle, this);
+                }
+
+                public override void Unpin() { }
+
+                protected override void Dispose(bool disposing) { }
+            }
+        }
+
         public static ReadOnlySequence<T> CreateSegments(params T[][] inputs) => CreateSegments((IEnumerable<T[]>)inputs);
 
         public static ReadOnlySequence<T> CreateSegments(IEnumerable<T[]> inputs)

src/System.Memory/tests/ReadOnlyBuffer/ReadOnlySequenceTests.byte.cs

@@ -21,6 +21,11 @@ public class Memory : ReadOnlySequenceTestsByte
             public Memory() : base(ReadOnlySequenceFactory<byte>.MemoryFactory) { }
         }
 
+        public class MemoryManager : ReadOnlySequenceTestsByte
+        {
+            public MemoryManager() : base(ReadOnlySequenceFactory<byte>.MemoryManagerFactory) { }
+        }
+
         public class SingleSegment : ReadOnlySequenceTestsByte
         {
             public SingleSegment() : base(ReadOnlySequenceFactory<byte>.SingleSegmentFactory) { }

src/packages.builds

@@ -24,6 +24,9 @@
       <AdditionalProperties>$(AdditionalProperties)</AdditionalProperties>
     </Project>
     <!-- add specific builds / pkgproj's here to include in servicing builds -->
+    <Project Include="$(MSBuildThisFileDirectory)System.Memory\pkg\System.Memory.pkgproj">
+      <AdditionalProperties>$(AdditionalProperties)</AdditionalProperties>
+    </Project>
   </ItemGroup>
 
   <!-- Need the PackageIndexFile file property from baseline.props -->