linux-kernel - Re: [CFT}[PATCH] coredump: Limit what can interrupt coredumps

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Message-ID: <CAHk-=wiax83WoS0p5nWvPhU_O+hcjXwv6q3DXV8Ejb62BfynhQ@mail.gmail.com>
Date:   Thu, 10 Jun 2021 12:10:20 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Olivier Langlois <olivier@...llion01.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        io-uring <io-uring@...r.kernel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Jens Axboe <axboe@...nel.dk>,
        "Pavel Begunkov>" <asml.silence@...il.com>,
        Oleg Nesterov <oleg@...hat.com>
Subject: Re: [CFT}[PATCH] coredump: Limit what can interrupt coredumps

On Thu, Jun 10, 2021 at 12:01 PM Eric W. Biederman
<ebiederm@...ssion.com> wrote:
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index f7c6ffcbd044..83d534deeb76 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -943,8 +943,6 @@ static bool prepare_signal(int sig, struct task_struct *p, bool force)
>         sigset_t flush;
>
>         if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
> -               if (!(signal->flags & SIGNAL_GROUP_EXIT))
> -                       return sig == SIGKILL;
>                 /*
>                  * The process is in the middle of dying, nothing to do.
>                  */

I do think this part of the patch is correct, but I'd like to know
what triggered this change?

It seems fairly harmless - SIGKILL used to be the only signal that was
passed through in the coredump case, now you pass through all
non-ignored signals.

But since SIGKILL is the only signal that is relevant for the
fatal_signal_pending() case, this change seems irrelevant for the
coredump issue. Any other signals passed through won't matter.

End result: I think removing those two lines is likely a good idea,
but I also suspect it could/should just be a separate patch with a
separate explanation for it.

Hmm?

              Linus