[GitHub] [pulsar] BewareMyPower commented on issue #6806: Segmentation fault in C++ library whilst deserializing messages

[GitBox <gi...@apache.org>]

BewareMyPower commented on issue #6806:
URL: https://github.com/apache/pulsar/issues/6806#issuecomment-618794964


   The problem may be the strange value (538973717) of `readIdx_` 。Could you provide the `payload` info of each frame?
   
   Following is the lifetime of `payload` (if I don't miss something):
   
   The payload first constructed in `ClientConnection::processIncomingBuffer()`:
   
   ```c++
               SharedBuffer payload = SharedBuffer::copy(incomingBuffer_.data(), payloadSize);
               incomingBuffer_.consume(payloadSize);
               // payload.readIdx_ should be 0 here
               handleIncomingMessage(incomingCmd_.message(), isChecksumValid, msgMetadata, payload);
   ```
   
   Then it comes to `ClientConnection::handleIncomingMessage()`, `payload` was passed to `consumer->messageReceived()` without any changes.
   
   In `ConsumerImpl::messageReceived`, `payload` may be modified in `decryptMessageIfNeeded()` and `uncompressMessageIfNeeded()`, while the previous may do nothing if encryption was not enabled.
   
   Then the payload was passed to the constructor of `Message` as `m.impl_->payload`, and next `m` was passed to `receiveIndividualMessagesFromBatch`:
   
   ```c++
       Message m(msg, metadata, payload, partitionIndex_);
       m.impl_->cnx_ = cnx.get();
       m.impl_->setTopicName(topic_);
       m.impl_->setRedeliveryCount(msg.redelivery_count());
   
       unsigned int numOfMessageReceived = 1;
       if (metadata.has_num_messages_in_batch()) {
           Lock lock(mutex_);
           // m.impl_->payload.readIdx_ should be 0 here
           numOfMessageReceived = receiveIndividualMessagesFromBatch(cnx, m, msg.redelivery_count());
   ```
   
   And next:
   
   ```c++
   uint32_t ConsumerImpl::receiveIndividualMessagesFromBatch(const ClientConnectionPtr& cnx,
                                                             Message& batchedMessage, int redeliveryCount) {
       unsigned int batchSize = batchedMessage.impl_->metadata.num_messages_in_batch();
       batchAcknowledgementTracker_.receivedMessage(batchedMessage);   // it doesn't modify batchedMessage
   
       int skippedMessages = 0;
   
       for (int i = 0; i < batchSize; i++) {
           // Now, batchedMessage.impl_->payload.readIdx_ becomes 538973717
           Message msg = Commands::deSerializeSingleMessageInBatch(batchedMessage, i);
   ```
   


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