[lldb] lldb-server may crash in the child process monitor thread

[slydiman]

Host::LaunchProcess() requires to SetMonitorProcessCallback. This callback is called from the child process monitor thread. We cannot control this thread anyway. GDBRemoteCommunicationServerPlatform::DebugserverProcessReaped() may cause a crash if this callback will be called from the child monitor thread after destroing the instance of GDBRemoteCommunicationServerPlatform.

llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp

Lines 521 to 526 in 2d36550

	void GDBRemoteCommunicationServerPlatform::DebugserverProcessReaped(
	lldb::pid_t pid) {
	std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
	m_port_map.FreePortForProcess(pid);
	m_spawned_pids.erase(pid);
	}

And m_port_map requires an own mutex guard here.

[llvmbot]

@llvm/issue-subscribers-lldb

Author: Dmitry Vasilyev (slydiman)

Host::LaunchProcess() requires to SetMonitorProcessCallback. This callback is called from the child process monitor thread. We cannot control this thread anyway. GDBRemoteCommunicationServerPlatform::DebugserverProcessReaped() may cause a crash if this callback will be called from the child monitor thread after destroing the instance of GDBRemoteCommunicationServerPlatform.

llvm-project/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp

Lines 521 to 526 in 2d36550

	void GDBRemoteCommunicationServerPlatform::DebugserverProcessReaped(
	lldb::pid_t pid) {
	std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
	m_port_map.FreePortForProcess(pid);
	m_spawned_pids.erase(pid);
	}

And m_port_map requires an own mutex guard here.