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Fixes issue with obfuscated libraries failing instrumentation #55

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Fixes issue with obfuscated libraries failing instrumentation #55

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4 changes: 2 additions & 2 deletions src/SharpFuzz.CommandLine/Program.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -81,9 +81,9 @@ public static int Main(string[] args)
Console.Error.WriteLine(ex.Message);
return 1;
}
catch
catch (Exception ex)
{
Console.Error.WriteLine("Failed to instrument the specified file, most likely because it's not a valid .NET assembly.");
Console.Error.WriteLine("Failed to instrument the specified file, most likely because it's not a valid .NET assembly: "+ex);
return 1;
}

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17 changes: 15 additions & 2 deletions src/SharpFuzz/Fuzzer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
using dnlib.DotNet;
using dnlib.DotNet.Emit;
using dnlib.DotNet.MD;
using dnlib.DotNet.Writer;

namespace SharpFuzz
{
Expand Down Expand Up @@ -66,7 +67,6 @@ public static IEnumerable<string> Instrument(
{
throw new InstrumentationException("The specified assembly is already instrumented.");
}

var common = typeof(Common.Trace).Assembly;
var commonName = common.GetName().Name;

Expand Down Expand Up @@ -141,7 +141,20 @@ private static SortedSet<string> Instrument(
}
}

src.Write(dst);
try
{
src.Write(dst);
}
catch (ModuleWriterException)
{
/*
* Likely if we got here it's because of obfuscation so we attempt to bypass it by keeping the old stack.
* If that doesn't solve it the error is likely to happen again which will bubble up to the user
*/
var writerOptions = new ModuleWriterOptions(src);
writerOptions.MetadataOptions.Flags |= MetadataFlags.KeepOldMaxStack;
src.Write(dst,writerOptions);
}
return types;
}

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