Re: [PATCH] signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die

Geert Uytterhoeven
2021-08-26T12:15:14Z

On Mon, Jul 26, 2021 at 11:08 PM Eric W. Biederman
<ebiederm@xmission.com> wrote:
> In the fpsp040 code when copyin or copyout fails call
> force_sigsegv(SIGSEGV) instead of do_exit(SIGSEGV).
>
> This solves a couple of problems. Because do_exit embeds the ptrace
> stop PTRACE_EVENT_EXIT a complete stack frame needs to be present for
> that to work correctly. There is always the information needed for a
> ptrace stop where get_signal is called. So exiting with a signal
> solves the ptrace issue.
>
> Further exiting with a signal ensures that all of the threads in a
> process are killed not just the thread that malfunctioned. Which
> avoids confusing userspace.
>
> To make force_sigsegv(SIGSEGV) work in fpsp040_die modify the code to
> save all of the registers and jump to ret_from_exception (which
> ultimately calls get_signal) after fpsp040_die returns.
>
> v2: Updated the branches to use gas's pseudo ops that automatically
> calculate the best branch instruction to use for the purpose.
>
> v1: Link: https://lkml.kernel.org/r/87a6m8kgtx.fsf_-_@disp2133
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds