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

Eric W. Biederman
2022-03-18T14:45:49Z

Kees Cook <keescook@chromium.org> writes:

> 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?

I did not. This is a pure ptrace change. Do you see a way that seccomp
could be involved?

Eric