fixes for fuzzers, some assumptions about pinning were not held (#1174)

Author: kevin-montrose

test/Garnet.fuzz/Program.cs

@@ -72,6 +72,19 @@ private static void WriteLine(FuzzOptions opts, string line)
         Console.WriteLine(line);
     }
 
+    /// <summary>
+    /// Log, if options allow it, a character to standard out.
+    /// </summary>
+    private static void Write(FuzzOptions opts, char c)
+    {
+        if (opts.Quiet)
+        {
+            return;
+        }
+
+        Console.Write(c);
+    }
+
     /// <summary>
     /// Log a message to standard error and exit the process.
     /// </summary>
@@ -95,16 +108,26 @@ private static void RunFuzzExample(FuzzOptions opts)
 
         foreach (var input in inputs)
         {
-            var inputCopy = input;
             for (var i = 0; i < repeatCount; i++)
             {
-                target(inputCopy);
+                target(input);
                 if (i != repeatCount - 1)
                 {
-                    // Force a new copy to wiggle things around in memory a bit
-                    inputCopy = [.. input];
+                    // Do some random allocations to shift things around for the next invocation
+                    GC.KeepAlive(GC.AllocateUninitializedArray<byte>(Random.Shared.Next(512), pinned: false));
+                    GC.KeepAlive(GC.AllocateUninitializedArray<byte>(Random.Shared.Next(512), pinned: true));
+                }
+
+                if (repeatCount != 1)
+                {
+                    Write(opts, '#');
                 }
             }
+
+            if (repeatCount != 1)
+            {
+                WriteLine(opts, "");
+            }
         }
 
         // Obtain a callback to run a fuzz target.

test/Garnet.fuzz/Targets/GarnetEndToEnd.cs

@@ -10,7 +10,6 @@
 using Embedded.server;
 using Garnet.server;
 using Garnet.server.Auth.Settings;
-
 using Tsavorite.core;
 
 namespace Garnet.fuzz.Targets
@@ -26,6 +25,8 @@ public sealed class GarnetEndToEnd : IFuzzerTarget
         /// <inheritdoc/>
         public static void Fuzz(ReadOnlySpan<byte> input)
         {
+            IFuzzerTarget.PrepareInput(ref input);
+
             try
             {
                 using var server = CreateServer();

test/Garnet.fuzz/Targets/IFuzzerTarget.cs

@@ -19,6 +19,18 @@ internal interface IFuzzerTarget
         /// </summary>
         static abstract void Fuzz(ReadOnlySpan<byte> input);
 
+        /// <summary>
+        /// Move input onto the POH, and do any other work necessary for
+        /// consistent fuzzing in Garnet.
+        /// </summary>
+        static void PrepareInput(ref ReadOnlySpan<byte> input)
+        {
+            var ret = GC.AllocateUninitializedArray<byte>(input.Length, pinned: true);
+            input.CopyTo(ret.AsSpan());
+
+            input = ret;
+        }
+
         /// <summary>
         /// Helper for throwing an exception when some post-run validation failed.
         /// </summary>

test/Garnet.fuzz/Targets/LuaScriptCompilation.cs

@@ -31,6 +31,8 @@ public sealed class LuaScriptCompilation : IFuzzerTarget
         /// <inheritdoc/>
         public static void Fuzz(ReadOnlySpan<byte> input)
         {
+            IFuzzerTarget.PrepareInput(ref input);
+
             foreach (var op in Options)
             {
                 try

test/Garnet.fuzz/Targets/RespCommandParsing.cs

@@ -16,6 +16,8 @@ public sealed class RespCommandParsing : IFuzzerTarget
         /// <inheritdoc/>
         public static void Fuzz(ReadOnlySpan<byte> input)
         {
+            IFuzzerTarget.PrepareInput(ref input);
+
             var session = new RespServerSession();
 
             try