Bug: Seg fault when deactivating rdk services caused by channel sharing in JSONRPCLink.h

[npoltorapavlo]

Problem/Opportunity

When deactivating rdk services there is a crash when destructing JSONRPC::LinkType:

Thread 7 "WorkerPool::Thr" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 11464.11577]
Downloading source file /usr/include/WPEFramework/core/Proxy.h
0xa7dd2c90 in WPEFramework::Core::ProxyType<WPEFramework::JSONRPC::LinkType<WPEFramework::Core::JSON::IElement>::CommunicationChannel>::~ProxyType (         
    this=0x214d214, __in_chrg=<optimized out>) at /usr/include/WPEFramework/core/Proxy.h:435

Crash address corresponds to _vptr.CommunicationChannel, unmapped:

(gdb) p $_siginfo._sifields._sigfault.si_addr
$9 = (void *) 0xaa293b44
(gdb) p *this
$11 = {_refCount = 0xa98bae64, _realObject = 0xa98ba978}
(gdb) p *this._realObject
$12 = {_vptr.CommunicationChannel = 0xaa293b20,...

When CommunicationChannel::Instance is called from library X, channelMap address is in library Y, and _vptr.CommunicationChannel address of returned channel is in library Z:

(gdb) p &channelMap
$31 = ...0xabc38c6c
(gdb) i symbol 0xabc38c6c
... /usr/lib/wpeframework/plugins/libWPEFrameworkY.so
(gdb) p *copy._realObject
$48 = {
  _vptr.CommunicationChannel = 0xa9823b20
(gdb) i symbol 0xa9823b20
... /usr/lib/wpeframework/plugins/libWPEFrameworkZ.so

If channel doesn't exist, channelMap returns a new channel with _vptr.CommunicationChannel address in the same library:

(gdb) p *_channel._realObject
$60 = {
  _vptr.CommunicationChannel = 0xaad83a40
(gdb) i symbol 0xaad83a40
vtable for ... + 8 in section .data.rel.ro of /usr/lib/wpeframework/plugins/libWPEFrameworkX.so

Looks like the problem relates to channel sharing in Thunder. Nothing prevents a library to unload and hence unload _vptr.CommunicationChannel of a channel being shared. Static channelMap instantiates once because there's one type - Core::ProxyMapType<string, JSONRPC::LinkType<Core::JSON::IElement>::CommunicationChannel>:

Thunder/Source/websocket/JSONRPCLink.h

Lines 206 to 213 in cc5d85b

	static Core::ProxyType<CommunicationChannel> Instance(const Core::NodeId& remoteNode, const string& callsign, const string& query)
	{
	static Core::ProxyMapType<string, CommunicationChannel> channelMap;
	string searchLine = remoteNode.HostAddress() + '@' + callsign;
	return (channelMap.template Instance<CommunicationChannel>(searchLine, remoteNode, callsign, query));
	}

Issue is specific to JSONRPC::LinkType/JSONRPC::SmartLinkType.

Steps to reproduce

Deactivate services that use JSONRPC::LinkType/JSONRPC::SmartLinkType.

Expected Behavior

No crash

Actual Behavior

Crash

Notes (Optional)

No response