Re: kern/58425: negation of pid or pgid is UB for INT_MIN

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Sun, 14 Jul 2024 14:57:10 +1000
    From:        matthew green <mrg%eterna23.net@localhost>
    Message-ID:  <22479.1720933030%splode.eterna23.net@localhost>

  | i recently was dealing with a trap related to exactly this.
  |
  | i was running atf on m68k virt68k qemu and it crashed the emulator
  | itself.  turns out -INT_MAX/-1 traps on x86.

I think you mean INT_MIN / -1 (INT_MIN != -INT_MAX - which is the whole
issue).

That would be a different problem than the pid one, which is just
taking -INT_MIN, no division, by anything, ever performed (I'm not
sure what a half of a pid_t would represent).   Further, it should
be fixed in the kernel now.

  | i have this uncommited/unsubmitted patch for qemu:
  |    https://www.netbsd.org/~mrg/patch-target_m68k_op_helper.c

Looks reasonable to me.   Though I know nothing about qemu

kre