Double Free for DynamicData for Sequences of Nested Structs (with minimal example)

[methylDragon]

Is there an already existing issue for this?

• I have searched the existing issues

Expected behavior

1. Create a dynamic data consisting of a sequence/array of nested structs
2. Populate that sequence with nested struct elements
3. Exit cleanly

Current behavior

1. Create a dynamic data consisting of a sequence/array of nested structs
2. Populate that sequence with nested struct elements
3. Exit cleanly <--- Errors print here

Specifically, the following error is printed per sequence/array element created.

[DYN_TYPES Error] Error deleting DynamicData. It isn't registered in the factory -> Function delete_data

Steps to reproduce

I've prepared a minimal example:
methylDragon/fastdds-pr-minimal-examples

Once built, run:

cd build

./src/nested-sequences-bug/could_not_delete

The relevant code can be found here.

Fast DDS version/commit

FastDDS 2.8.x: 78473a0

The examples workspace is using that specific SHA in the submodule, for convenience.

Platform/Architecture

Other. Please specify in Additional context section.

Transport layer

Default configuration, UDPv4 & SHM

Additional context

This is on 22.04, but I don't think the platform matters in this case.

The error is being emitted from DynamicDataFactory's destructor call.

What I suspect is happening is, as each dynamic data is added to the sequence/array, the data gets registered once to the factory on creation. But on destruction, the factory destroys the instance, but the sequence/array destruction triggers a second destruction.

This causes the double free. (I think)

XML configuration file

No response

Relevant log output

nested_sequence: 
	[0] = <struct/bitset>
		inner_uint32: 1

	[1] = <struct/bitset>
		inner_uint32: 2

2022-09-22 16:04:48.127 [DYN_TYPES Error] Error deleting DynamicData. It isn't registered in the factory -> Function delete_data
2022-09-22 16:04:48.127 [DYN_TYPES Error] Error deleting DynamicData. It isn't registered in the factory -> Function delete_data

### Network traffic capture

_No response_

[methylDragon]

This bug is still happening, are there any updates?

[methylDragon]

If it helps, I found that commenting out this line fixes the issue. But I don't know what the fallout of removing default_array_value_ is.

This issue happens when dynamic datas are copied with DynamicDataFactory::create_copy(). But I'm not sure what exactly is happening.

[JLBuenoLopez]

There are several known issues related with Dynamic Types in Fast DDS. Thus, a refactor is being undertaken in order to fix the Dynamic Types implementation. It is expected to be released with Fast DDS v2.11.0 scheduled for June 2023.

[elianalf]

The Dynamic Types refactor has been integrated in Fast DDS v3.0.0 which will be released soon. This issue may be solved in the new version of Fast DDS, so I will close this issue for now. If the issue persists, feel free to reopen it.