netbsd test error: MSan: Uninitialized Memory in fpu_clear

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 79e1e9de4198 bsd.own.mk: If NOPIE is defined, set MKPIE=no.
git tree: netbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=15a72368580000
kernel config: https://syzkaller.appspot.com/x/.config?x=739e57438eb9ed9e
dashboard link: https://syzkaller.appspot.com/bug?extid=8678c88535f9ce1f5ffe
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97)

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d27243404b97/disk-79e1e9de.raw.xz
netbsd.gdb: https://storage.googleapis.com/syzbot-assets/ac28df9a7e1b/netbsd-79e1e9de.gdb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8678c8...@syzkaller.appspotmail.com

[ 6.3074834] panic: MSan: Uninitialized Pool Memory From fork1()

[ 6.3228815] cpu0: Begin traceback...
[ 6.3274361] vpanic() at netbsd:vpanic+0xc9d sys/kern/subr_prf.c:-1
[ 6.3574474] panic() at netbsd:panic+0x1b3
[ 6.3874481] __msan_warning() at netbsd:__msan_warning+0x11e kmsan_report_inline sys/kern/subr_msan.c:250 [inline]
[ 6.3874481] __msan_warning() at netbsd:__msan_warning+0x11e sys/kern/subr_msan.c:631
[ 6.4174425] fpu_clear() at netbsd:fpu_clear+0x86b sys/arch/x86/x86/fpu.c:-1
[ 6.4374439] setregs() at netbsd:setregs+0x142 sys/arch/amd64/amd64/machdep.c:1382
[ 6.4674501] execve_runproc() at netbsd:execve_runproc+0x4786 sys/kern/kern_exec.c:1202
[ 6.4974509] sys_execve() at netbsd:sys_execve+0x264 execve1 sys/kern/kern_exec.c:1485 [inline]
[ 6.4974509] sys_execve() at netbsd:sys_execve+0x264 sys/kern/kern_exec.c:608
[ 6.5274485] start_init() at netbsd:start_init+0x13b6 sys/kern/init_main.c:1121
[ 6.5382915] cpu0: End traceback...
[ 6.5499006] fatal breakpoint trap in supervisor mode
[ 6.5499006] trap type 1 code 0 rip 0xffffffff80236885 cs 0x8 rflags 0x282 cr2 0x7f7fffe370e0 ilevel 0x5 rsp 0xffff9d80bf6b04d0
[ 6.5659229] curlwp 0xffff9d8011e39100 pid 1.1 lowest kstack 0xffff9d80bf6a92c0
Stopped in pid 1.1 (init) at netbsd:breakpoint+0x5: leave
breakpoint() at netbsd:breakpoint+0x5
vpanic() at netbsd:vpanic+0xc9d sys/kern/subr_prf.c:-1
panic() at netbsd:panic+0x1b3
__msan_warning() at netbsd:__msan_warning+0x11e kmsan_report_inline sys/kern/subr_msan.c:250 [inline]
__msan_warning() at netbsd:__msan_warning+0x11e sys/kern/subr_msan.c:631
fpu_clear() at netbsd:fpu_clear+0x86b sys/arch/x86/x86/fpu.c:-1
setregs() at netbsd:setregs+0x142 sys/arch/amd64/amd64/machdep.c:1382
execve_runproc() at netbsd:execve_runproc+0x4786 sys/kern/kern_exec.c:1202
sys_execve() at netbsd:sys_execve+0x264 execve1 sys/kern/kern_exec.c:1485 [inline]
sys_execve() at netbsd:sys_execve+0x264 sys/kern/kern_exec.c:608
start_init() at netbsd:start_init+0x13b6 sys/kern/init_main.c:1121
ds 6918
es 8b3
fs 4c0
gs 0
rdi 5
rsi 0
rbp ffff9d80bf6b04d0
rbx 0
rdx 1
rcx ffff9d8011e39100
rax ffff9d8012006918
r8 0
r9 500000000000000
--db_more--

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