[debugger] Access invalid memory address using PointerValue Command. (#18537)

* Validate the address that came from IDE using PointerValue. The IDE can send an invalid address and it was crashing mono.

Fixes #18191
Fixes #15612

Co-authored-by: Aleksey Kliger (λgeek) <akliger@gmail.com>

3 files changed, 52 insertions, 2 deletions

diff --git a/mcs/class/Mono.Debugger.Soft/Mono.Debugger.Soft/PointerValue.cs b/mcs/class/Mono.Debugger.Soft/Mono.Debugger.Soft/PointerValue.cs
index 2cf9dfa418b..d407b417b51 100644
--- a/mcs/class/Mono.Debugger.Soft/Mono.Debugger.Soft/PointerValue.cs
+++ b/mcs/class/Mono.Debugger.Soft/Mono.Debugger.Soft/PointerValue.cs
@@ -51,10 +51,19 @@ namespace Mono.Debugger.Soft
 		// Since protocol version 2.46
 		public Value Value {
 			get {
+				ValueImpl value;
 				if (Address == 0)
 					return null;
-
-				return vm.DecodeValue (vm.conn.Pointer_GetValue (Address, Type));
+				try {
+					value = vm.conn.Pointer_GetValue (Address, Type);
+				}
+				catch (CommandException ex) {
+				if (ex.ErrorCode == ErrorCode.INVALID_ARGUMENT)
+					throw new ArgumentException ("Invalid pointer address.");
+				else
+					throw;
+				}
+				return vm.DecodeValue (value);
 			}
 		}
 
diff --git a/mcs/class/Mono.Debugger.Soft/Test/dtest-app.cs b/mcs/class/Mono.Debugger.Soft/Test/dtest-app.cs
index 945ea48c38b..1bbb04d4709 100644
--- a/mcs/class/Mono.Debugger.Soft/Test/dtest-app.cs
+++ b/mcs/class/Mono.Debugger.Soft/Test/dtest-app.cs
@@ -609,6 +609,10 @@ public class Tests : TestsBase, ITest2
 		fixed_size_array();
 		test_new_exception_filter();
 		test_async_debug_generics();
+		if (args.Length >0 && args [0] == "pointer_arguments2") {
+			pointers2 ();
+			return 0;
+		}
 		return 3;
 	}
 
@@ -2232,6 +2236,17 @@ public class Tests : TestsBase, ITest2
 		rtMethod.Invoke(rtObject, new object[] { });
 	}
 	
+	public static unsafe void pointer_arguments2 (int* a) {
+		*a = 0;
+	}
+
+	[MethodImplAttribute (MethodImplOptions.NoInlining)]
+	public static unsafe void pointers2 () {
+		int[] a = new [] {1,2,3};
+		fixed (int* pa = a)
+			pointer_arguments2 (pa);
+	}
+
 	[MethodImplAttribute (MethodImplOptions.NoInlining)]
 	public static void new_thread_hybrid_exception() {
 		try
diff --git a/mcs/class/Mono.Debugger.Soft/Test/dtest.cs b/mcs/class/Mono.Debugger.Soft/Test/dtest.cs
index 05d112e3f88..7be3ae3e6eb 100644
--- a/mcs/class/Mono.Debugger.Soft/Test/dtest.cs
+++ b/mcs/class/Mono.Debugger.Soft/Test/dtest.cs
@@ -5174,6 +5174,32 @@ public class DebuggerTests
 		e = step_in_await ("MoveNext", e);
 		e = step_in_await ("MoveNext", e);
 	}
+
+	[Test]
+	public void InvalidPointer_GetValue () {
+		vm.Detach ();
+		Start (dtest_app_path, "pointer_arguments2");
+		Event e = run_until ("pointer_arguments2");
+		var frame = e.Thread.GetFrames () [0];
+
+		var param = frame.Method.GetParameters()[0];
+		Assert.AreEqual("Int32*", param.ParameterType.Name);
+
+		var pointerValue = frame.GetValue(param) as PointerValue;
+		Assert.AreEqual("Int32*", pointerValue.Type.Name);
+
+
+		var pointerValue2 = new PointerValue (pointerValue.VirtualMachine, pointerValue.Type, 200);
+
+		try {
+			var val = pointerValue2.Value;
+		}
+		catch (ArgumentException ex) {
+			Assert.IsInstanceOfType (typeof (ArgumentException), ex);
+		}
+	}
+
+
 	
 #endif
 } // class DebuggerTests