linux-kernel - Re: [PATCH 14/20] exit/syscall_user_dispatch: Send ordinary signals on failure

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Date:   Thu, 21 Oct 2021 12:05:00 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH 14/20] exit/syscall_user_dispatch: Send ordinary signals on failure

Kees Cook <keescook@...omium.org> writes:

> On Thu, Oct 21, 2021 at 11:37:23AM -0500, Eric W. Biederman wrote:
>> Kees Cook <keescook@...omium.org> writes:
>> 
>> > On Wed, Oct 20, 2021 at 12:44:00PM -0500, Eric W. Biederman wrote:
>> >> Use force_fatal_sig instead of calling do_exit directly.  This ensures
>> >> the ordinary signal handling path gets invoked, core dumps as
>> >> appropriate get created, and for multi-threaded processes all of the
>> >> threads are terminated not just a single thread.
>> >
>> > Yeah, looks good. Should be no visible behavior change.
>> 
>> It is observable in that an entire multi-threaded process gets
>> terminated instead of a single thread.  But since these events should
>> be handling of extra-ordinary events I don't expect there is anyone
>> who wants to have a thread of their process survive.
>
> Right -- sorry, I should have said that more clearly: "Besides the
> single thread death now taking the whole process, there's not behavior
> change (i.e. the signal delivery)." Still looks good to me.

Yes.  I just didn't want that single vs multi-thread case to sneak up on
people.  Especially since that is part of the questionable behavior that
I am sorting out.

Eric