Re: [PATCH 1/2] ptrace: Move setting/clearing ptrace_message into ptrace_stop

Kees Cook
2022-03-17T19:10:22Z

On Tue, Mar 15, 2022 at 06:21:08PM -0500, Eric W. Biederman wrote:
>
> Today ptrace_message is easy to overlook as it not a core part of
> ptrace_stop. It has been overlooked so much that there are places
> that set ptrace_message and don't clear it, and places that never set
> it. So if you get an unlucky sequence of events the ptracer may be
> able to read a ptrace_message that does not apply to the current
> ptrace stop.
>
> Move setting of ptrace_message into ptrace_stop so that it always gets
> set before the stop, and always gets cleared after the stop. This
> prevents non-sense from being reported to userspace and makes
> ptrace_message more visible in the ptrace helper functions so that
> kernel developers can see it.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

This looks good to me. Did you happen to run the seccomp selftests
before/after these changes?

Reviewed-by: Kees Cook <keescook@chromium.org>

--
Kees Cook