From b9f50901a498fe8f2c0a93f412ece19267076c31 Mon Sep 17 00:00:00 2001
From: Siegfried Pammer <siegfriedpammer@gmail.com>
Date: Mon, 13 Jan 2025 19:35:15 +0100
Subject: [PATCH] Fix #3367: Add extra validation to
 TransformDecimalCtorToConstant to prevent crashes with obfuscated assemblies.

---
 .../TestCases/Pretty/ConstantsTests.cs                   | 9 +++++++++
 .../IL/Transforms/EarlyExpressionTransforms.cs           | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/ICSharpCode.Decompiler.Tests/TestCases/Pretty/ConstantsTests.cs b/ICSharpCode.Decompiler.Tests/TestCases/Pretty/ConstantsTests.cs
index 7bada42063..851813fb53 100644
--- a/ICSharpCode.Decompiler.Tests/TestCases/Pretty/ConstantsTests.cs
+++ b/ICSharpCode.Decompiler.Tests/TestCases/Pretty/ConstantsTests.cs
@@ -260,6 +260,15 @@ public byte Issue2166b(int x)
 			return (byte)(x & 0x10);
 		}
 
+		public decimal Issue3367()
+		{
+#if CS70
+			return new decimal(0, 0, 0, isNegative: false, 29);
+#else
+			return new decimal(0, 0, 0, false, 29);
+#endif
+		}
+
 		private void ExpectUInt64(ulong _)
 		{
 
diff --git a/ICSharpCode.Decompiler/IL/Transforms/EarlyExpressionTransforms.cs b/ICSharpCode.Decompiler/IL/Transforms/EarlyExpressionTransforms.cs
index 3d99d04009..2316732e90 100644
--- a/ICSharpCode.Decompiler/IL/Transforms/EarlyExpressionTransforms.cs
+++ b/ICSharpCode.Decompiler/IL/Transforms/EarlyExpressionTransforms.cs
@@ -213,7 +213,7 @@ bool TransformDecimalCtorToConstant(NewObj inst, out LdcDecimal result)
 				int lo, mid, hi, isNegative, scale;
 				if (args[0].MatchLdcI4(out lo) && args[1].MatchLdcI4(out mid) &&
 					args[2].MatchLdcI4(out hi) && args[3].MatchLdcI4(out isNegative) &&
-					args[4].MatchLdcI4(out scale))
+					args[4].MatchLdcI4(out scale) && scale <= 28)
 				{
 					result = new LdcDecimal(new decimal(lo, mid, hi, isNegative != 0, (byte)scale));
 					return true;