panic: kernel diagnostic assertion "TAILQ_EMPTY(&kq->kq_head)" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_event.c", line 1268
Stopped at db_enter+0x18: addq $0x8,%rsp
TID PID UID PRFLAGS PFLAGS CPU COMMAND
*483275 29128 0 0 0x4000000 0 syz-executor.0
174656 62957 0 0x2 0x480 1 syz-executor.1
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff823c3c11) at panic+0x15e sys/kern/subr_prf.c:218
__assert(ffffffff8242d86c,ffffffff82425328,4f4,ffffffff823ad335) at __assert+0x2b sys/kern/subr_prf.c:162
kqueue_terminate(ffff8000214ac000,fffffd80686ec220) at kqueue_terminate+0x152 sys/kern/kern_event.c:1268
kqueue_close(fffffd8069a12130,ffff80002123c7e0) at kqueue_close+0x40 sys/kern/kern_event.c:1286
fdrop(fffffd8069a12130,ffff80002123c7e0) at fdrop+0xc2 sys/kern/kern_descrip.c:1279
closef(fffffd8069a12130,ffff80002123c7e0) at closef+0x11c sys/kern/kern_descrip.c:1263
finishdup(ffff80002123c7e0,fffffd8069a122f8,4,3,ffff8000222dfb40,2) at finishdup+0x321 sys/kern/kern_descrip.c:691
dodup3(ffff80002123c7e0,4,3,0,ffff8000222dfb40) at dodup3+0x5cf sys/kern/kern_descrip.c:397
syscall(ffff8000222dfbc0) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff8000222dfbc0) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xff030cab130, count: 4
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}> set $maxwidth = 0
ddb{0}> show panic
kernel diagnostic assertion "TAILQ_EMPTY(&kq->kq_head)" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_event.c", line 1268
ddb{0}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff823c3c11) at panic+0x15e sys/kern/subr_prf.c:218
__assert(ffffffff8242d86c,ffffffff82425328,4f4,ffffffff823ad335) at __assert+0x2b sys/kern/subr_prf.c:162
kqueue_terminate(ffff8000214ac000,fffffd80686ec220) at kqueue_terminate+0x152 sys/kern/kern_event.c:1268
kqueue_close(fffffd8069a12130,ffff80002123c7e0) at kqueue_close+0x40 sys/kern/kern_event.c:1286
fdrop(fffffd8069a12130,ffff80002123c7e0) at fdrop+0xc2 sys/kern/kern_descrip.c:1279
closef(fffffd8069a12130,ffff80002123c7e0) at closef+0x11c sys/kern/kern_descrip.c:1263
finishdup(ffff80002123c7e0,fffffd8069a122f8,4,3,ffff8000222dfb40,2) at finishdup+0x321 sys/kern/kern_descrip.c:691
dodup3(ffff80002123c7e0,4,3,0,ffff8000222dfb40) at dodup3+0x5cf sys/kern/kern_descrip.c:397
syscall(ffff8000222dfbc0) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff8000222dfbc0) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xff030cab130, count: -11
ddb{0}> show registers
rdi 0
rsi 0x1
rbp 0xffff8000222df760
rbx 0xffff8000222df770
rdx 0x8b
rcx 0x2
rax 0x1
r8 0xffffffff821c43c5 kprintf+0x145
r9 0x1
r10 0x2b1eb14d2e853785
r11 0x109c9fc891b5566b
r12 0x3000000008
r13 0xffff8000222df810
r14 0x100
r15 0x1
rip 0xffffffff81df8258 db_enter+0x18
cs 0x8
rflags 0x246
rsp 0xffff8000222df750
ss 0x10
db_enter+0x18: addq $0x8,%rsp
ddb{0}> show proc
PROC (syz-executor.0) pid=483275 stat=onproc
flags process=0 proc=4000000<THREAD>
pri=65, usrpri=65, nice=20
forw=0xffffffffffffffff, list=0xffff80002123cfc0,0xffffffff828cc870
process=0xffff800021235960 user=0xffff8000222da000, vmspace=0xfffffd80084968a0
estcpu=15, cpticks=2, pctcpu=0.0
user=0, sys=2, intr=0
ddb{0}> ps
PID TID PPID UID S FLAGS WAIT COMMAND
29128 158928 47874 0 2 0 syz-executor.0
29128 73032 47874 0 3 0x4000080 kqread syz-executor.0
*29128 483275 47874 0 7 0x4000000 syz-executor.0
62957 174656 24241 0 7 0x482 syz-executor.1
47874 72719 24241 0 2 0x2 syz-executor.0
24241 29677 86784 0 3 0x82 thrsleep syz-fuzzer
24241 212995 86784 0 3 0x4000082 thrsleep syz-fuzzer
24241 275826 86784 0 3 0x4000082 thrsleep syz-fuzzer
24241 60661 86784 0 3 0x4000082 kqread syz-fuzzer
24241 367464 86784 0 3 0x4000082 thrsleep syz-fuzzer
24241 105237 86784 0 3 0x4000082 thrsleep syz-fuzzer
24241 176077 86784 0 3 0x4000082 thrsleep syz-fuzzer
24241 251763 86784 0 3 0x4000082 thrsleep syz-fuzzer
86784 8880 42810 0 3 0x10008a sigsusp ksh
42810 418943 42095 0 3 0x92 select sshd
53128 95631 1 0 3 0x100083 ttyin getty
42095 323626 1 0 3 0x80 select sshd
42605 227811 15979 74 3 0x100092 bpf pflogd
15979 295403 1 0 3 0x80 netio pflogd
26789 111695 50244 73 3 0x100090 kqread syslogd
50244 1796 1 0 3 0x100082 netio syslogd
47110 346746 1 77 3 0x100090 poll dhclient
51936 62735 1 0 3 0x80 poll dhclient
86468 203016 0 0 3 0x14200 bored smr
6753 412620 0 0 2 0x14200 zerothread
83659 346568 0 0 3 0x14200 aiodoned aiodoned
46730 323586 0 0 3 0x14200 syncer update
25715 520712 0 0 3 0x14200 cleaner cleaner
34779 9088 0 0 3 0x14200 reaper reaper
85014 61930 0 0 3 0x14200 pgdaemon pagedaemon
81558 314126 0 0 3 0x14200 bored crynlk
38693 175608 0 0 3 0x14200 bored crypto
54336 125190 0 0 3 0x14200 bored viomb
13677 360890 0 0 3 0x40014200 acpi0 acpi0
50155 289024 0 0 3 0x40014200 idle1
58589 417037 0 0 3 0x14200 bored softnet
68316 241999 0 0 3 0x14200 bored systqmp
18871 326611 0 0 3 0x14200 bored systq
59609 359580 0 0 2 0x40014200 softclock
45042 464869 0 0 3 0x40014200 idle0
1 112848 0 0 3 0x82 wait init
0 0 -1 0 3 0x10200 scheduler swapper
ddb{0}> show all locks
Process 29128 (syz-executor.0) thread 0xffff80002123c7e0 (483275)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff828cca98)
#0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0 witness_lock+0x4b0 sys/kern/subr_witness.c:1176
#1 kqueue_close+0x2d sys/kern/kern_event.c:1284
#2 fdrop+0xc2 sys/kern/kern_descrip.c:1279
#3 closef+0x11c sys/kern/kern_descrip.c:1263
#4 finishdup+0x321 sys/kern/kern_descrip.c:691
#5 dodup3+0x5cf sys/kern/kern_descrip.c:397
#6 syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#6 syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590
#7 Xsyscall+0x128
ddb{0}> show malloc
Type InUse MemUse HighUse Limit Requests Type Lim
devbuf 9490 6441K 6446K 78643K 26441 0
pcb 13 8K 8K 78643K 451 0
rtable 111 3K 3K 78643K 205 0
ifaddr 44 10K 10K 78643K 45 0
sysctl 2 0K 0K 78643K 2 0
counters 44 34K 34K 78643K 44 0
ioctlops 0 0K 4K 78643K 3005 0
iov 0 0K 16K 78643K 945 0
mount 1 1K 1K 78643K 1 0
vnodes 1222 77K 77K 78643K 10934 0
UFS quota 1 32K 32K 78643K 1 0
UFS mount 5 36K 36K 78643K 5 0
shm 2 1K 5K 78643K 168 0
VM map 2 1K 1K 78643K 2 0
sem 12 0K 0K 78643K 330 0
dirhash 12 2K 2K 78643K 12 0
ACPI 1697 195K 286K 78643K 12598 0
file desc 5 13K 25K 78643K 53845 0
proc 60 63K 95K 78643K 448 0
subproc 32 2K 2K 78643K 34 0
NFS srvsock 1 0K 0K 78643K 1 0
NFS daemon 1 16K 16K 78643K 1 0
in_multi 33 2K 2K 78643K 33 0
ether_multi 1 0K 0K 78643K 1 0
ISOFS mount 1 32K 32K 78643K 1 0
MSDOSFS mount 1 16K 16K 78643K 1 0
ttys 55 254K 254K 78643K 55 0
exec 0 0K 2K 78643K 358 0
pagedep 1 8K 8K 78643K 1 0
inodedep 1 32K 32K 78643K 1 0
newblk 1 0K 0K 78643K 1 0
VM swap 7 26K 26K 78643K 7 0
UVM amap 185 26K 27K 78643K 124331 0
UVM aobj 131 4K 4K 78643K 267 0
memdesc 1 4K 4K 78643K 1 0
crypto data 1 1K 1K 78643K 1 0
NDP 6 0K 0K 78643K 10 0
temp 106 3981K 4047K 78643K 122538 0
kqueue 7 8K 15K 78643K 4691 0
SYN cache 2 16K 16K 78643K 2 0
ddb{0}> show all pools
Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
arp 64 6 0 0 1 0 1 1 0 8 0
plcache 128 20 0 0 1 0 1 1 0 8 0
rtpcb 120 19 0 17 1 0 1 1 0 8 0
rtentry 112 48 0 1 2 0 2 2 0 8 0
unpcb 120 16078 0 16068 1 0 1 1 0 8 0
syncache 296 4 0 4 1 1 0 1 0 8 0
tcpcb 736 400 0 396 14 13 1 6 0 8 0
inpcb 304 4936 0 4929 1 0 1 1 0 8 0
nd6 48 9 0 0 1 0 1 1 0 8 0
kcovpl 48 2 0 0 1 0 1 1 0 8 0
pffrag 232 8 0 8 4 3 1 1 0 482 1
pffrnode 88 7 0 7 4 3 1 1 0 8 1
pffrent 40 143 0 143 4 3 1 1 0 8 1
pfosfp 40 1428 0 1005 5 0 5 5 0 8 0
pfosfpen 112 1428 0 714 21 0 21 21 0 8 0
pfstitem 24 72 0 70 1 0 1 1 0 8 0
pfstkey 112 72 0 70 2 1 1 2 0 8 0
pfstate 328 72 0 70 5 4 1 4 0 8 0
pfrule 1360 21 0 16 2 1 1 2 0 8 0
art_heap8 4096 1 0 0 1 0 1 1 0 8 0
art_heap4 256 193 0 0 13 0 13 13 0 8 0
art_table 32 194 0 0 2 0 2 2 0 8 0
art_node 16 47 0 4 1 0 1 1 0 8 0
semapl 112 328 0 318 1 0 1 1 0 8 0
shmpl 112 264 0 136 4 0 4 4 0 8 0
dirhash 1024 17 0 0 3 0 3 3 0 8 0
dino2pl 256 60661 0 59260 88 0 88 88 0 8 0
ffsino 272 60661 0 59260 94 0 94 94 0 8 0
nchpl 144 137840 0 136233 60 0 60 60 0 8 0
uvmvnodes 72 5926 0 0 108 0 108 108 0 8 0
vnodes 224 5926 0 0 349 0 349 349 0 8 0
namei 1024 370721 0 370721 1 0 1 1 0 8 1
percpumem 16 33 0 0 1 0 1 1 0 8 0
scxspl 216 345652 0 345652 9 8 1 8 0 8 1
plimitpl 152 181 0 173 1 0 1 1 0 8 0
sigapl 424 54061 0 54029 4 0 4 4 0 8 0
futexpl 56 235236 0 235236 3 2 1 1 0 8 1
knotepl 112 4654 0 4634 1 0 1 1 0 8 0
kqueuepl 168 6801 0 6716 6 2 4 4 0 8 0
pipepl 336 4427 0 4416 60 59 1 2 0 8 0
fdescpl 496 54045 0 54029 3 0 3 3 0 8 0
filepl 152 180810 0 180706 11 6 5 5 0 8 0
lockfpl 104 5184 0 5183 1 0 1 1 0 8 0
lockfspl 48 2142 0 2141 1 0 1 1 0 8 0
sessionpl 144 18 0 7 1 0 1 1 0 8 0
pgrppl 48 236 0 225 1 0 1 1 0 8 0
ucredpl 96 19810 0 19801 1 0 1 1 0 8 0
zombiepl 144 54029 0 54028 1 0 1 1 0 8 0
processpl 1080 54061 0 54028 3 0 3 3 0 8 0
procpl 672 123677 0 123635 8 4 4 5 0 8 0
sockpl 432 21059 0 21040 18 15 3 4 0 8 0
mcl64k 65536 35 0 0 4 1 3 3 0 8 0
mcl16k 16384 30 0 0 3 1 2 3 0 8 0
mcl12k 12288 72 0 0 3 1 2 2 0 8 0
mcl9k 9216 32 0 0 2 0 2 2 0 8 0
mcl8k 8192 27 0 0 3 0 3 3 0 8 0
mcl4k 4096 25 0 0 4 1 3 3 0 8 0
mcl2k2 2112 26 0 0 2 0 2 2 0 8 0
mcl2k 2048 178 0 0 13 1 12 12 0 8 0
mtagpl 96 1 0 0 1 0 1 1 0 8 0
mbufpl 256 1543 0 0 18 3 15 18 0 8 0
bufpl 280 57692 0 51445 447 0 447 447 0 8 0
anonpl 24 3382145 0 3376960 63 27 36 59 0 186 0
amapchunkpl 152 194273 0 194099 16 8 8 8 0 158 0
amappl16 200 165683 0 165504 32 21 11 23 0 8 0
amappl15 192 2 0 0 1 0 1 1 0 8 0
amappl14 184 26692 0 26686 1 0 1 1 0 8 0
amappl13 176 27 0 24 1 0 1 1 0 8 0
amappl12 168 5 0 3 1 0 1 1 0 8 0
amappl11 160 27214 0 27196 1 0 1 1 0 8 0
amappl10 152 15 0 9 1 0 1 1 0 8 0
amappl9 144 283 0 283 1 1 0 1 0 8 0
amappl8 136 1264 0 1128 5 0 5 5 0 8 0
amappl7 128 243 0 235 1 0 1 1 0 8 0
amappl6 120 69 0 57 1 0 1 1 0 8 0
amappl5 112 55640 0 55622 1 0 1 1 0 8 0
amappl4 104 27671 0 27645 1 0 1 1 0 8 0
amappl3 96 3359 0 3351 1 0 1 1 0 8 0
amappl2 88 459003 0 458931 3 1 2 3 0 8 0
amappl1 80 1497475 0 1497001 27 15 12 21 0 8 0
amappl 88 123914 0 123862 2 0 2 2 0 92 0
dma4096 4096 1 0 1 1 1 0 1 0 8 0
dma1024 1024 1 0 0 1 0 1 1 0 8 0
dma256 256 6 0 6 1 1 0 1 0 8 0
dma128 128 253 0 253 1 1 0 1 0 8 0
dma64 64 6 0 6 1 1 0 1 0 8 0
dma32 32 7 0 7 1 1 0 1 0 8 0
dma16 16 18 0 17 1 0 1 1 0 8 0
aobjpl 64 266 0 136 3 0 3 3 0 8 0
uaddrrnd 24 54045 0 54029 1 0 1 1 0 8 0
uaddrbest 32 2 0 0 1 0 1 1 0 8 0
uaddr 24 54045 0 54029 1 0 1 1 0 8 0
vmmpekpl 168 310292 0 310267 2 0 2 2 0 8 0
vmmpepl 168 6664272 0 6662770 190 118 72 83 0 357 1
vmsppl 368 54044 0 54029 2 0 2 2 0 8 0
rwobjpl 56 1381814 0 1380843 50 35 15 19 0 8 0
pdppl 4096 108097 0 108058 57 16 41 45 0 8 2
pvpl 32 10536487 0 10528244 232 158 74 117 0 265 0
pmappl 232 54044 0 54029 2 1 1 2 0 8 0
extentpl 40 58 0 40 1 0 1 1 0 8 0
phpool 112 383 0 98 9 0 9 9 0 8 0
ddb{0}> machine ddbcpu 0
Invalid cpu 0
ddb{0}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff823c3c11) at panic+0x15e sys/kern/subr_prf.c:218
__assert(ffffffff8242d86c,ffffffff82425328,4f4,ffffffff823ad335) at __assert+0x2b sys/kern/subr_prf.c:162
kqueue_terminate(ffff8000214ac000,fffffd80686ec220) at kqueue_terminate+0x152 sys/kern/kern_event.c:1268
kqueue_close(fffffd8069a12130,ffff80002123c7e0) at kqueue_close+0x40 sys/kern/kern_event.c:1286
fdrop(fffffd8069a12130,ffff80002123c7e0) at fdrop+0xc2 sys/kern/kern_descrip.c:1279
closef(fffffd8069a12130,ffff80002123c7e0) at closef+0x11c sys/kern/kern_descrip.c:1263
finishdup(ffff80002123c7e0,fffffd8069a122f8,4,3,ffff8000222dfb40,2) at finishdup+0x321 sys/kern/kern_descrip.c:691
dodup3(ffff80002123c7e0,4,3,0,ffff8000222dfb40) at dodup3+0x5cf sys/kern/kern_descrip.c:397
syscall(ffff8000222dfbc0) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff8000222dfbc0) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:590
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xff030cab130, count: -11
ddb{0}> machine ddbcpu 1