freebsd test error: panic: _proc_set_cred: ref NUM not NUM on cred ADDR

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2a8a6179eb6c etc/mtree/BSD.include.dist: Remove libipt-dev
git tree: freebsd-src
console output: https://syzkaller.appspot.com/x/log.txt?x=176f5812580000
dashboard link: https://syzkaller.appspot.com/bug?extid=74624c6fcbb384ea0113
userspace arch: i386

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+74624c...@syzkaller.appspotmail.com

panic: _proc_set_cred: ref 2 not 1 on cred 0xfffffe0007685300
cpuid = 0
time = 1762428775
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0xc6/frame 0xfffffe0056e90790
kdb_backtrace() at kdb_backtrace+0xd0/frame 0xfffffe0056e908f0
vpanic() at vpanic+0x257/frame 0xfffffe0056e90ab0
panic() at panic+0xb5/frame 0xfffffe0056e90b80
_proc_set_cred() at _proc_set_cred+0x307/frame 0xfffffe0056e90bf0
proc_set_cred() at proc_set_cred+0x1f/frame 0xfffffe0056e90c10
sys_setloginclass() at sys_setloginclass+0x18a/frame 0xfffffe0056e90d10
amd64_syscall() at amd64_syscall+0x4e2/frame 0xfffffe0056e90f30
fast_syscall_common() at fast_syscall_common+0xf8/frame 0xfffffe0056e90f30
--- syscall (524, FreeBSD ELF64, setloginclass), rip = 0x24da6a, rsp = 0x821326ba8, rbp = 0x821326c30 ---
KDB: enter: panic
[ thread pid 17 tid 100085 ]
Stopped at kdb_enter+0x6e: movq $0,0x25897e7(%rip)
db> serialport: Connected to syzkaller.us-central1-b.ci-freebsd-i386-test-0 port 1 (session ID: ffe67c1c3f7d7a271f0363e8b473ac961c7637195204e480d73331cc718f9869, active connections: 1).


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