Author: Jason Molenda Date: 2023-11-01T16:14:36-07:00 New Revision: 66b92830c963158c9f74dd5533265c28d60cc265
URL: https://github.com/llvm/llvm-project/commit/66b92830c963158c9f74dd5533265c28d60cc265 DIFF: https://github.com/llvm/llvm-project/commit/66b92830c963158c9f74dd5533265c28d60cc265.diff LOG: [lldb] [debugserver] Shut down the exception thread when clearing (#70979) MachProcess has a MachTask as an ivar. In the MachProcess dtor, we call MachTask::Clear() to clear its state, before running the dtor of all our ivars, including the MachTask one. When we attach on darwin, MachProcess calls MachTask::StartExceptionThread which does the task_for_pid and then starts a thread to listen for mach messages. Then MachProcess calls ptrace(PT_ATTACHEXC). If that ptrace() fails, MachProcess will call MachTask::Clear. But the exception thread is now up & running and is not stopped; its ivars will be reset by the Clear() method, and its object will be freed after the dtor runs. Actually eliciting a crash in this scenario is very timing sensitive; I hand-modified debugserver to fail to PT_ATTACHEXC trying to simulate it on my desktop and was unable. But looking at the source, and an occasional crash report we've received, it's clear that this is possible. rdar://117521198 Added: Modified: lldb/tools/debugserver/source/MacOSX/MachTask.mm Removed: ################################################################################ diff --git a/lldb/tools/debugserver/source/MacOSX/MachTask.mm b/lldb/tools/debugserver/source/MacOSX/MachTask.mm index 4f5b4039243f662..fd2ac64ac6cf79c 100644 --- a/lldb/tools/debugserver/source/MacOSX/MachTask.mm +++ b/lldb/tools/debugserver/source/MacOSX/MachTask.mm @@ -145,6 +145,8 @@ //---------------------------------------------------------------------- void MachTask::Clear() { // Do any cleanup needed for this task + if (m_exception_thread) + ShutDownExcecptionThread(); m_task = TASK_NULL; m_exception_thread = 0; m_exception_port = MACH_PORT_NULL; _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
