panic: witness_warn Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *185854 53111 32767 0x10 0x4000000 0 syz-executor1 55568 11423 32767 0x10 0 1 syz-executor1 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic() at panic+0x16c sys/kern/subr_prf.c:208 witness_warn(93745f98a5579a01,0,ffff800020b93530) at witness_warn+0x6e0 witness_debugger sys/kern/subr_witness.c:2546 [inline] witness_warn(93745f98a5579a01,0,ffff800020b93530) at witness_warn+0x6e0 sys/kern/subr_witness.c:1462 userret(80e849b64a94cb66) at userret+0x361 sys/kern/kern_sig.c:1899 syscall(fc3ce2037ac7553c) at syscall+0x680 mi_syscall_return sys/sys/syscall_mi.h:122 [inline] syscall(fc3ce2037ac7553c) at syscall+0x680 sys/arch/amd64/amd64/trap.c:605 Xsyscall(6,5,d,0,3,83c296161a0) at Xsyscall+0x128 end of kernel end trace frame: 0x83ed97fe1a0, count: 9 https://www.openbsd.org/ddb.html describes the minimum info required in bug reports. Insufficient info makes it difficult to find and fix bugs. ddb{0}> ddb{0}> set $lines = 0 ddb{0}> show panic witness_warn ddb{0}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic() at panic+0x16c sys/kern/subr_prf.c:208 witness_warn(93745f98a5579a01,0,ffff800020b93530) at witness_warn+0x6e0 witness_debugger sys/kern/subr_witness.c:2546 [inline] witness_warn(93745f98a5579a01,0,ffff800020b93530) at witness_warn+0x6e0 sys/kern/subr_witness.c:1462 userret(80e849b64a94cb66) at userret+0x361 sys/kern/kern_sig.c:1899 syscall(fc3ce2037ac7553c) at syscall+0x680 mi_syscall_return sys/sys/syscall_mi.h:122 [inline] syscall(fc3ce2037ac7553c) at syscall+0x680 sys/arch/amd64/amd64/trap.c:605 Xsyscall(6,5,d,0,3,83c296161a0) at Xsyscall+0x128 end of kernel end trace frame: 0x83ed97fe1a0, count: -6 ddb{0}> show registers rdi 0xffffffff817aed67 db_enter+0x17 rsi 0x55bc __ALIGN_SIZE+0x45bc rbp 0xffff800020cbb270 rbx 0xffff800020cbb310 rdx 0x55bd __ALIGN_SIZE+0x45bd rcx 0xffff800001346000 rax 0xffff800001346000 r8 0xffffffff81ba5254 kprintf+0x174 r9 0x1 r10 0xb4071bac7a979ec6 r11 0x4c599a4937071550 r12 0x3000000008 r13 0xffff800020cbb280 r14 0x100 r15 0x1 rip 0xffffffff817aed68 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff800020cbb260 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor1) pid=185854 stat=onproc flags process=10 proc=4000000 pri=32, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff800020b92bd0,0xffffffff82307ab0 process=0xffff800020b946a0 user=0xffff800020cb6000, vmspace=0xfffffd806e92b170 estcpu=36, cpticks=2, pctcpu=0.0 user=0, sys=2, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 53111 194783 11423 32767 2 0x10 syz-executor1 53111 174223 11423 32767 3 0x4000090 fsleep syz-executor1 53111 10013 11423 32767 2 0x4000010 syz-executor1 *53111 185854 11423 32767 7 0x4000010 syz-executor1 11423 55568 7771 32767 7 0x10 syz-executor1 7771 120625 8831 0 3 0x82 wait syz-executor1 17105 288526 92839 32767 3 0x10 biowait syz-executor0 92839 455593 8831 0 3 0x82 wait syz-executor0 86179 372612 0 0 3 0x14200 bored sosplice 8831 185707 55528 0 3 0x82 thrsleep syz-fuzzer 8831 74843 55528 0 2 0x4000082 syz-fuzzer 8831 466204 55528 0 3 0x4000082 thrsleep syz-fuzzer 8831 115727 55528 0 3 0x4000082 kqread syz-fuzzer 8831 241615 55528 0 3 0x4000082 thrsleep syz-fuzzer 8831 352757 55528 0 3 0x4000082 thrsleep syz-fuzzer 8831 455464 55528 0 3 0x4000082 thrsleep syz-fuzzer 8831 443954 55528 0 3 0x4000082 thrsleep syz-fuzzer 8831 431804 55528 0 3 0x4000082 thrsleep syz-fuzzer 8831 308659 55528 0 2 0x4000082 syz-fuzzer 8831 33403 55528 0 3 0x4000082 thrsleep syz-fuzzer 8831 492437 55528 0 3 0x4000082 thrsleep syz-fuzzer 55528 5934 67636 0 3 0x10008a pause ksh 67636 279450 51113 0 2 0x92 sshd 83117 272782 1 0 3 0x100083 ttyin getty 51113 213393 1 0 3 0x80 select sshd 16717 61929 20743 73 2 0x100090 syslogd 20743 369648 1 0 3 0x100082 netio syslogd 66370 39756 1 77 3 0x100090 poll dhclient 51271 76272 1 0 3 0x80 poll dhclient 88482 289571 0 0 3 0x14200 pgzero zerothread 84953 372233 0 0 3 0x14200 aiodoned aiodoned 92565 257122 0 0 3 0x14200 syncer update 86093 391550 0 0 3 0x14200 cleaner cleaner 76638 466043 0 0 3 0x14200 reaper reaper 76938 139884 0 0 3 0x14200 pgdaemon pagedaemon 3843 141133 0 0 3 0x14200 bored crynlk 66068 366310 0 0 3 0x14200 bored crypto 46563 481517 0 0 3 0x40014200 acpi0 acpi0 92384 136272 0 0 3 0x40014200 idle1 56291 474930 0 0 3 0x14200 bored softnet 81620 66107 0 0 3 0x14200 bored systqmp 30360 495008 0 0 3 0x14200 bored systq 54402 89964 0 0 3 0x40014200 bored softclock 54665 313465 0 0 3 0x40014200 idle0 1 272026 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper