On Wed, Jun 27, 2018 at 03:13:02PM +0300, Georgi Guninski wrote:
> Does this BUG_ON() gets hit on mips?
>
> in 4.17.2 ./kernel/exit.c
>
> do_group_exit(int exit_code)
> {
> struct signal_struct *sig = current->signal;
>
> BUG_ON(exit_code & 0x80);
>
> |do_group_exit| is called from
>
> ./kernel/signal.c:2482: do_group_exit(ksig->info.si_signo);
>
> Appears to me si_signo can be 0x80 (in decimal 128) because of:
>
> arch/mips/include/uapi/asm/signal.h:15:#define _NSIG 128
>
> Probably testcase will be:
> $kill -128 `pidof program`
I've hit this by accident before, while tweaking GDB on MIPS. See here:
[RFC] kernel/signal.c: avoid BUG_ON with SIG128 (MIPS):
https://patchwork.linux-mips.org/patch/5343/
[v2] MIPS: Reduce _NSIG from 128 to 127 to avoid BUG_ON:
https://patchwork.linux-mips.org/patch/5461/
[v3] kernel/signal.c: fix BUG_ON with SIG128 (MIPS):
https://patchwork.linux-mips.org/patch/5538/
https://patchwork.linux-mips.org/patch/5550/
[v4] MIPS: Reduce _NSIG from 128 to 127 to avoid BUG_ON:
https://patchwork.linux-mips.org/patch/5564/
I think the fear of subtle user ABI breakage was probably prominent in
why it never got properly fixed. It'd be nice to get some resolution
though.
Cheers
James
