Re: [PATCH v3] kernel/signal.c: fix BUG_ON with SIG128 (MIPS)

From: Ralf Baechle
Date: Wed Jun 26 2013 - 12:02:16 EST


On Wed, Jun 26, 2013 at 12:07:44PM +0100, James Hogan wrote:

> > IMO changing the ABI by reducing _NSIG to 127 or 126 isn't appropriate
> > for stable.
>
> How does this look for a nasty/stable fix?

> diff --git a/kernel/signal.c b/kernel/signal.c
> index 113411b..9ea8f4f 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -2366,8 +2366,14 @@ relock:
>
> /*
> * Death signals, no core dump.
> + *
> + * Some architectures (MIPS) have 128 signals which doesn't play
> + * nicely with the exit code since there are only 7 bits to
> + * store the terminating signal number. Mask out higher bits to
> + * avoid overflowing into the core dump bit and triggering
> + * BUG_ON in do_group_exit.
> */
> - do_group_exit(info->si_signo);
> + do_group_exit(info->si_signo & 0x7f);
> /* NOTREACHED */
> }
> spin_unlock_irq(&sighand->siglock);

Looks like something which I think we could live with.

Clearly it also scores in the "nasty" category, so fits the bill ;)

Ralf
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