Re: [GIT PULL] Please pull proc and exec work for 5.7-rc1

Linus Torvalds
2020-04-09T16:16:01Z

On Thu, Apr 9, 2020 at 8:01 AM Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> When a thread going about it's ordinary business receives the SIGKILL
> from de_thread the thread changes course and finds it's way to do_exit.
> In do_exit the thread calls ptrace_event(PTRACE_EVENT_EXIT, ...) and
> blocks waiting for the tracer to let it continue.

Hah.

That code isn't _supposed_ to block.

may_ptrace_stop() is supposed to stop the blocking exactly so that it
doesn't deadlock.

I wonder why that doesn't work..

[ Goes and look ]

Oh. I see.

That ptrace_may_stop() only ever considered core-dumping, not execve().

But if _that_ is the reason for the deadlock, then it's trivially fixed.

Famous last words..

Linus