kern/55629: execsnoop + t_origin = panic

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         55629
>Category:       kern
>Synopsis:       execsnoop + t_origin = panic
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Aug 31 07:40:00 +0000 2020
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date 2020.08.30.21.20.06
>Organization:
>Environment:
System: NetBSD
Architecture: x86_64
Machine: amd64
>Description:

Starting execsnoop and then running the kernel/t_origin test panics the
system:

  kernel/t_origin (101/882): 2 test cases
      origin_simple: [0.517825s] Passed.
      origin_simple_32: [ 1727.5182166] prevented execution of 0x0 (SMEP)
  [ 1727.5682167] fatal page fault in supervisor mode
  [ 1727.6182167] trap type 6 code 0x10 rip 0 cs 0x8 rflags 0x10202 cr2 0 ilevel 0 rsp 0xffffb704c5a5ef58
  [ 1727.7282168] curlwp 0xffffacaa1b7d45c0 pid 24375.24375 lowest kstack 0xffffb704c5a5a2c0
  [ 1727.8282169] panic: trap
  [ 1727.8582169] cpu2: Begin traceback...
  [ 1727.8982169] vpanic() at netbsd:vpanic+0x152
  [ 1727.9482167] snprintf() at netbsd:snprintf
  [ 1727.9982170] startlwp() at netbsd:startlwp
  [ 1728.0482168] alltraps() at netbsd:alltraps+0xc3
  [ 1728.1082169] syscall() at netbsd:syscall+0xe7
  [ 1728.1582170] --- syscall (number 0) ---
  [ 1728.2082172] netbsd:syscall+0xe7:
  [ 1728.2382170] cpu2: End traceback...

  [ 1728.2882171] dumping to dev 0,1 (offset=1271, size=16753241):

>How-To-Repeat:

execsnoop >/tmp/log &
cd /usr/tests/kernel
atf-run t_origin

>Fix: