Re: [PATCH 08/16] ptrace: Only populate last_siginfo from ptrace

Eric W. Biederman
2022-06-06T22:16:01Z

Oleg Nesterov <oleg@redhat.com> writes:

> On 05/18, Eric W. Biederman wrote:
>>
>> The code in ptrace_signal to populate siginfo if the signal number
>> changed is buggy. If the tracer contined the tracee using
>> ptrace_detach it is guaranteed to use the real_parent (or possibly a
>> new tracer) but definitely not the origional tracer to populate si_pid
>> and si_uid.
>
> I guess nobody cares. As the comment says
>
> If the debugger wanted something
> specific in the siginfo structure then it should
> have updated *info via PTRACE_SETSIGINFO.
>
> otherwise I don't think si_pid/si_uid have any value.

No one has complained so it is clearly no one cares. So it is
definitely not a regression. Or even anything that needs to be
backported.

However si_pid and si_uid are defined with SI_USER are defined
to be whomever sent the signal. So I would argue by definition
those values are wrong.

> However the patch looks fine to me, just the word "buggy" looks a bit
> too strong imo.

I guess I am in general agreement. Perhaps I can just say they values
are wrong by definition?

Eric