Enforce a maximum entry limit during append operations (#36843)

* Enforce a maximum entry limit during append operations

* Add test for this change

Author: yufengwangca

src/app/clusters/user-label-server/user-label-server.cpp

@@ -143,6 +143,7 @@ CHIP_ERROR UserLabelAttrAccess::WriteLabelList(const ConcreteDataAttributePath &
 
         return provider->SetUserLabelList(endpoint, labelList);
     }
+
     if (aPath.mListOp == ConcreteDataAttributePath::ListOperation::AppendItem)
     {
         Structs::LabelStruct::DecodableType entry;

src/app/tests/suites/TestUserLabelClusterConstraints.yaml

@@ -55,3 +55,35 @@ tests:
               ]
       response:
           error: CONSTRAINT_ERROR
+
+    - label: "Attempt to write a large label list"
+      command: "writeAttribute"
+      attribute: "LabelList"
+      arguments:
+          value: [
+                  # Example repeated user labels to blow up the maximum allowed
+                  { Label: "roomName", Value: "master bedroom 1" },
+                  { Label: "orientation", Value: "east" },
+                  { Label: "floor", Value: "2" },
+                  { Label: "roomType", Value: "bedroom" },
+                  { Label: "someKey5", Value: "someVal5" },
+                  { Label: "someKey6", Value: "someVal6" },
+                  { Label: "someKey7", Value: "someVal7" },
+                  { Label: "someKey8", Value: "someVal8" },
+                  { Label: "someKey9", Value: "someVal9" },
+                  { Label: "someKey10", Value: "someVal10" },
+                  { Label: "someKey11", Value: "someVal11" },
+                  { Label: "someKey12", Value: "someVal12" },
+                  { Label: "someKey13", Value: "someVal13" },
+                  { Label: "someKey14", Value: "someVal14" },
+                  { Label: "someKey15", Value: "someVal15" },
+                  { Label: "someKey16", Value: "someVal16" },
+                  { Label: "someKey17", Value: "someVal17" },
+                  { Label: "someKey18", Value: "someVal18" },
+                  { Label: "someKey19", Value: "someVal19" },
+                  { Label: "someKey20", Value: "someVal20" },
+              ]
+      response:
+          # When the cluster runs out of capacity to store these entries,
+          # we expect a FAILURE get returned.
+          error: FAILURE

src/platform/DeviceInfoProvider.cpp

@@ -82,11 +82,16 @@ CHIP_ERROR DeviceInfoProvider::AppendUserLabel(EndpointId endpoint, const UserLa
 {
     size_t length;
 
-    // Increase the size of UserLabelList by 1
+    // Fetch current list length
     ReturnErrorOnFailure(GetUserLabelLength(endpoint, length));
-    ReturnErrorOnFailure(SetUserLabelLength(endpoint, length + 1));
 
-    // Append the user label at the end of UserLabelList
+    if (length >= kMaxUserLabelListLength)
+    {
+        return CHIP_ERROR_NO_MEMORY;
+    }
+
+    // Add the new entry to the list
+    ReturnErrorOnFailure(SetUserLabelLength(endpoint, length + 1));
     ReturnErrorOnFailure(SetUserLabelAt(endpoint, length, label));
 
     return CHIP_NO_ERROR;