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From:   "Eric W. Biederman" <ebiederm@xmission.com>
To:     Oleg Nesterov <oleg@redhat.com>
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Date:   Mon, 06 Jun 2022 17:16:01 -0500
In-Reply-To: <20220524152725.GE14347@redhat.com> (Oleg Nesterov's message of
        "Tue, 24 May 2022 17:27:25 +0200")
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Subject: Re: [PATCH 08/16] ptrace: Only populate last_siginfo from ptrace
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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