Fix escaped strings for TryGetDateTime(Offset)

src/libraries/System.Text.Json/src/System/Text/Json/JsonHelpers.Date.cs

@@ -117,6 +117,12 @@ public static bool IsValidDateTimeOffsetParseLength(int length)
             return IsInRangeInclusive(length, JsonConstants.MinimumDateTimeParseLength, JsonConstants.MaximumEscapedDateTimeOffsetParseLength);
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool IsValidUnescapedDateTimeOffsetParseLength(int length)
+        {
+            return IsInRangeInclusive(length, JsonConstants.MinimumDateTimeParseLength, JsonConstants.MaximumDateTimeOffsetParseLength);
+        }
+
         /// <summary>
         /// Parse the given UTF-8 <paramref name="source"/> as extended ISO 8601 format.
         /// </summary>

src/libraries/System.Text.Json/src/System/Text/Json/Reader/JsonReaderHelper.cs

@@ -260,7 +260,7 @@ public static bool TryGetEscapedDateTime(ReadOnlySpan<byte> source, out DateTime
             sourceUnescaped = sourceUnescaped.Slice(0, written);
             Debug.Assert(!sourceUnescaped.IsEmpty);
 
-            if (sourceUnescaped.Length <= JsonConstants.MaximumDateTimeOffsetParseLength
+            if (JsonHelpers.IsValidUnescapedDateTimeOffsetParseLength(sourceUnescaped.Length)
                 && JsonHelpers.TryParseAsISO(sourceUnescaped, out DateTime tmp))
             {
                 value = tmp;
@@ -285,7 +285,7 @@ public static bool TryGetEscapedDateTimeOffset(ReadOnlySpan<byte> source, out Da
             sourceUnescaped = sourceUnescaped.Slice(0, written);
             Debug.Assert(!sourceUnescaped.IsEmpty);
 
-            if (sourceUnescaped.Length <= JsonConstants.MaximumDateTimeOffsetParseLength
+            if (JsonHelpers.IsValidUnescapedDateTimeOffsetParseLength(sourceUnescaped.Length)
                 && JsonHelpers.TryParseAsISO(sourceUnescaped, out DateTimeOffset tmp))
             {
                 value = tmp;

src/libraries/System.Text.Json/tests/System.Text.Json.Tests/JsonDocumentTests.cs

@@ -2047,6 +2047,31 @@ void assertOdd(JsonElement elem)
             }
         }
 
+        [Theory]
+        [InlineData(">>")]
+        [InlineData(">>>")]
+        [InlineData(">>a")]
+        [InlineData(">a>")]
+        public static void TryGetDateTimeAndOffset_InvalidPropertyValue(string testData)
+        {
+            string jsonString = JsonSerializer.Serialize(new { DateTimeProperty = testData });
+
+            byte[] dataUtf8 = Encoding.UTF8.GetBytes(jsonString);
+
+            using (JsonDocument doc = JsonDocument.Parse(dataUtf8, default))
+            {
+                JsonElement root = doc.RootElement;
+
+                Assert.False(root.GetProperty("DateTimeProperty").TryGetDateTime(out DateTime datetimeValue));
+                Assert.Equal(default, datetimeValue);
+                Assert.Throws<FormatException>(() => root.GetProperty("DateTimeProperty").GetDateTime());
+
+                Assert.False(root.GetProperty("DateTimeProperty").TryGetDateTimeOffset(out DateTimeOffset datetimeOffsetValue));
+                Assert.Equal(default, datetimeOffsetValue);
+                Assert.Throws<FormatException>(() => root.GetProperty("DateTimeProperty").GetDateTimeOffset());
+            }
+        }
+
         [Theory]
         [InlineData("")]
         [InlineData("    ")]

src/libraries/System.Text.Json/tests/System.Text.Json.Tests/Utf8JsonReaderTests.TryGet.Date.cs

@@ -252,5 +252,23 @@ static void Test(string testString, bool isFinalBlock)
             Test(testString, isFinalBlock: true);
             Test(testString, isFinalBlock: false);
         }
+
+        [Theory]
+        [InlineData(@"""\u001c\u0001""")]
+        [InlineData(@"""\u001c\u0001\u0001""")]
+        public static void TryGetDateTimeAndOffset_InvalidPropertyValue(string testString)
+        {
+            var dataUtf8 = Encoding.UTF8.GetBytes(testString);
+            var json = new Utf8JsonReader(dataUtf8);
+            Assert.True(json.Read());
+
+            Assert.False(json.TryGetDateTime(out var dateTime));
+            Assert.Equal(default, dateTime);
+            JsonTestHelper.AssertThrows<FormatException>(json, (json) => json.GetDateTime());
+
+            Assert.False(json.TryGetDateTimeOffset(out var dateTimeOffset));
+            Assert.Equal(default, dateTimeOffset);
+            JsonTestHelper.AssertThrows<FormatException>(json, (json) => json.GetDateTimeOffset());
+        }
     }
 }