On 06/24, Eric W. Biederman wrote:

Oleg Nesterov [off-list ref] writes:

quoted

Add Eric.

OK, I agree, it seems we need a simple fix.

Acked-by: Oleg Nesterov <oleg@redhat.com>

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But let me add some "offtopic" notes... Why do we actually need this fix?

kill_something_info(). But at first glance sys_kill/kill_something_info
can simply use SEND_SIG_NOINFO? If yes, this makes sense anyway, I will
re-check...

....

So I think tracing the basic kill syscall is interesting.

It uses an explicit siginfo.  It does that so it can choose
between setting si_code to SI_TKILL and SI_USER.

If the signal number is -1 it sends to every process in the
system (or at least the pid namespace).

That will require translation.

Most probably I was wrong, I didn't try to re-check yet.

But at first glance kill_something_info() never use SI_TKILL, and
__send_signal_locked(SEND_SIG_NOINFO) will do the necessary translation,
in this case si_pid/si_uid are the current task's pid/uid.

But again, I am not sure. Didn't have to to actually look at this code.

I suspect just fixing send_signal_locked looks the easiest,
especially if you make the siginfo parameter const.

Yes, agreed, and I have already acked this patch.

I think we can improve this unconditional rewrite later, on top of this fix.

Oleg.