Reject a padding whose double overflows instead of letting it pass validation [patch]

IconHelper.Test/ArgumentsTests.cs

@@ -161,6 +161,23 @@ public void ValidateAcceptsTheSmallestSizesThePipelineHandles(int size, int padd
 		Assert.IsTrue(valid, $"Expected --size {size} --padding {padding} to be valid but got: {string.Join(", ", errors)}");
 	}
 
+	[TestMethod]
+	[DataRow((int.MaxValue / 2) + 1)]
+	[DataRow(int.MaxValue)]
+	public void ValidateRejectsPaddingWhoseDoubleOverflowsAnInt(int padding)
+	{
+		using TempDirectory temp = new();
+		Arguments args = ValidArguments(temp);
+		args.Size = 128;
+		args.Padding = padding;
+
+		bool valid = args.Validate(out Collection<string> errors);
+
+		Assert.IsFalse(valid, $"Padding {padding} is far above half of 128 and should be rejected.");
+		Assert.HasCount(1, errors);
+		Assert.AreEqual("Padding must be less than half the size of the image.", errors[0]);
+	}
+
 	[TestMethod]
 	public void ValidateRejectsPaddingThatLeavesNoContentOnASmallSize()
 	{

IconHelper/Arguments.cs

@@ -53,7 +53,8 @@ internal bool Validate(out Collection<string> errors)
 		// Doubled rather than halved: Size / 2 rounds an odd size down, which rejected padding the
 		// pipeline handles (--size 3 --padding 1) and even the default 0 at --size 1. This is the
 		// bound EffectivePadding clamps to, (size - 1) / 2, so at least one pixel of content is left.
-		else if (Size > 0 && Padding * 2 >= Size)
+		// Widened to long so a padding above int.MaxValue / 2 cannot wrap negative and pass.
+		else if (Size > 0 && (long)Padding * 2 >= Size)
 		{
 			errors.Add("Padding must be less than half the size of the image.");
 		}