[mle] reject ChildIdResponse if included dataset TLV is ill-formed (#7599)

This commit contains the following changes:

- The `Dataset` method which reads the dataset TLVs from a message
  is renamed to `ReadFromMessage()` and after reading the TLVs, it
  also checks that the TLVs in the Dataset are valid (well-formed).
- The `Active/PendingDataset::Save()` methods are updated to return
  error in the case the parsed dataset is not well-formed.
- The `Mle::HandleChildIdRequest()` rejects the response if the
  included dataset is not well-formed. This ensures that device
  stays detached if it cannot accept and save the dataset it gets
  from the parent candidate.

src/core/meshcop/dataset.cpp

@@ -435,13 +435,15 @@ Error Dataset::SetTlv(const Tlv &aTlv)
     return SetTlv(aTlv.GetType(), aTlv.GetValue(), aTlv.GetLength());
 }
 
-Error Dataset::Set(const Message &aMessage, uint16_t aOffset, uint8_t aLength)
+Error Dataset::ReadFromMessage(const Message &aMessage, uint16_t aOffset, uint8_t aLength)
 {
-    Error error = kErrorInvalidArgs;
+    Error error = kErrorParse;
 
     SuccessOrExit(aMessage.Read(aOffset, mTlvs, aLength));
     mLength = aLength;
 
+    VerifyOrExit(IsValid(), error = kErrorParse);
+
     mUpdateTime = TimerMilli::GetNow();
     error       = kErrorNone;
 

src/core/meshcop/dataset.hpp

@@ -782,17 +782,17 @@ public:
     }
 
     /**
-     * This method sets the Dataset using TLVs stored in a message buffer.
+     * This method reads the Dataset from a given message and checks that it is well-formed and valid.
      *
-     * @param[in]  aMessage  The message buffer.
-     * @param[in]  aOffset   The message buffer offset where the dataset starts.
-     * @param[in]  aLength   The TLVs length in the message buffer in bytes.
+     * @param[in]  aMessage  The message to read from.
+     * @param[in]  aOffset   The offset in @p aMessage to start reading the Dataset TLVs.
+     * @param[in]  aLength   The dataset length in bytes.
      *
-     * @retval kErrorNone         Successfully set the Dataset.
-     * @retval kErrorInvalidArgs  The values of @p aOffset and @p aLength are not valid for @p aMessage.
+     * @retval kErrorNone    Successfully read and validated the Dataset.
+     * @retval kErrorParse   Could not read or parse the dataset from @p aMessage.
      *
      */
-    Error Set(const Message &aMessage, uint16_t aOffset, uint8_t aLength);
+    Error ReadFromMessage(const Message &aMessage, uint16_t aOffset, uint8_t aLength);
 
     /**
      * This method sets the Dataset using an existing Dataset.

src/core/meshcop/dataset_manager.cpp

@@ -140,7 +140,7 @@ Error DatasetManager::Save(const Dataset &aDataset)
 
     if (isNetworkkeyUpdated || compare > 0)
     {
-        IgnoreError(mLocal.Save(aDataset));
+        SuccessOrExit(error = mLocal.Save(aDataset));
 
 #if OPENTHREAD_FTD
         Get<NetworkData::Leader>().IncrementVersionAndStableVersion();
@@ -690,9 +690,9 @@ Error ActiveDataset::Save(const Timestamp &aTimestamp, const Message &aMessage,
     Error   error = kErrorNone;
     Dataset dataset;
 
-    SuccessOrExit(error = dataset.Set(aMessage, aOffset, aLength));
+    SuccessOrExit(error = dataset.ReadFromMessage(aMessage, aOffset, aLength));
     dataset.SetTimestamp(Dataset::kActive, aTimestamp);
-    IgnoreError(DatasetManager::Save(dataset));
+    error = DatasetManager::Save(dataset);
 
 exit:
     return error;
@@ -777,9 +777,9 @@ Error PendingDataset::Save(const Timestamp &aTimestamp, const Message &aMessage,
     Error   error = kErrorNone;
     Dataset dataset;
 
-    SuccessOrExit(error = dataset.Set(aMessage, aOffset, aLength));
+    SuccessOrExit(error = dataset.ReadFromMessage(aMessage, aOffset, aLength));
     dataset.SetTimestamp(Dataset::kPending, aTimestamp);
-    IgnoreError(DatasetManager::Save(dataset));
+    SuccessOrExit(error = DatasetManager::Save(dataset));
     StartDelayTimer();
 
 exit:

src/core/meshcop/dataset_manager.hpp

@@ -272,6 +272,9 @@ protected:
      * @param[in]  aOffset     The offset where the Operational Dataset begins.
      * @param[in]  aLength     The length of the Operational Dataset.
      *
+     * @retval kErrorNone     Successfully parsed the Dataset from the @p aMessage and saved it.
+     * @retval kErrorParse    Could not parse the Dataset from @p aMessage.
+     *
      */
     Error Save(const Timestamp &aTimestamp, const Message &aMessage, uint16_t aOffset, uint8_t aLength);
 
@@ -419,6 +422,9 @@ public:
      * @param[in]  aOffset     The offset where the Operational Dataset begins.
      * @param[in]  aLength     The length of the Operational Dataset.
      *
+     * @retval kErrorNone     Successfully parsed the Dataset from the @p aMessage and saved it.
+     * @retval kErrorParse    Could not parse the Dataset from @p aMessage.
+     *
      */
     Error Save(const Timestamp &aTimestamp, const Message &aMessage, uint16_t aOffset, uint8_t aLength);
 

src/core/thread/mle.cpp

@@ -3696,7 +3696,8 @@ void Mle::HandleChildIdResponse(const Message &         aMessage,
         if (Tlv::FindTlvOffset(aMessage, Tlv::kActiveDataset, offset) == kErrorNone)
         {
             IgnoreError(aMessage.Read(offset, tlv));
-            IgnoreError(Get<MeshCoP::ActiveDataset>().Save(timestamp, aMessage, offset + sizeof(tlv), tlv.GetLength()));
+            SuccessOrExit(
+                error = Get<MeshCoP::ActiveDataset>().Save(timestamp, aMessage, offset + sizeof(tlv), tlv.GetLength()));
         }
         break;