panic: kqueue_scan:LINE: kq=ADDR kn=ADDR knote !ACTIVE

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syzbot

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Jan 6, 2020, 2:42:10 AM1/6/20
to syzkaller-o...@googlegroups.com
Hello,

syzbot found the following crash on:

HEAD commit: 5899a108 Zero initialize cpus and memory variables up front
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=17a3f13ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=bf87b6915a88cd0d
dashboard link: https://syzkaller.appspot.com/bug?extid=1c98ab5344aaf68cf1a6

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1c98ab...@syzkaller.appspotmail.com

panic: kqueue_scan:879: kq=0xfffffd8070e7fe38 kn=0xfffffd806eb3f000
knote !ACTIVE
Stopped at db_enter+0x18: addq $0x8,%rsp
TID PID UID PRFLAGS PFLAGS CPU COMMAND
* 78370 55879 0 0 0x4000000 1K syz-executor.1
185309 67480 0 0x2 0x480 0 syz-executor.0
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff821c296c) at panic+0x15c sys/kern/subr_prf.c:207
kqueue_do_check(fffffd8070e7fe38,ffffffff82211dae,36f) at
kqueue_do_check+0x232 sys/kern/kern_event.c:587
kqueue_scan(fffffd8070e7fe38,7e,0,0,ffff800020ad6018,ffff800021ba172c) at
kqueue_scan+0x68c sys/kern/kern_event.c:880
sys_kevent(ffff800020ad6018,ffff800021ba17a8,ffff800021ba17f0) at
sys_kevent+0x48b sys/kern/kern_event.c:569
syscall(ffff800021ba1870) at syscall+0x4a4 mi_syscall
sys/sys/syscall_mi.h:92 [inline]
syscall(ffff800021ba1870) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x8fbaac0d980, count: 8
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{1}>
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
kqueue_scan:879: kq=0xfffffd8070e7fe38 kn=0xfffffd806eb3f000 knote !ACTIVE
ddb{1}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff821c296c) at panic+0x15c sys/kern/subr_prf.c:207
kqueue_do_check(fffffd8070e7fe38,ffffffff82211dae,36f) at
kqueue_do_check+0x232 sys/kern/kern_event.c:587
kqueue_scan(fffffd8070e7fe38,7e,0,0,ffff800020ad6018,ffff800021ba172c) at
kqueue_scan+0x68c sys/kern/kern_event.c:880
sys_kevent(ffff800020ad6018,ffff800021ba17a8,ffff800021ba17f0) at
sys_kevent+0x48b sys/kern/kern_event.c:569
syscall(ffff800021ba1870) at syscall+0x4a4 mi_syscall
sys/sys/syscall_mi.h:92 [inline]
syscall(ffff800021ba1870) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x8fbaac0d980, count: -7
ddb{1}> show registers
rdi 0xffffffff81181907 db_enter+0x17
rsi 0x2a77 __ALIGN_SIZE+0x1a77
rbp 0xffff800021ba11f0
rbx 0xffff800021ba12a0
rdx 0x2a78 __ALIGN_SIZE+0x1a78
rcx 0xffff800022d9a000
rax 0xffff800022d9a000
r8 0xffffffff81e1f45f kprintf+0x16f
r9 0x1
r10 0x25
r11 0x22d115ca247af452
r12 0x3000000008
r13 0xffff800021ba1200
r14 0x100
r15 0x1
rip 0xffffffff81181908 db_enter+0x18
cs 0x8
rflags 0x246
rsp 0xffff800021ba11e0
ss 0x10
db_enter+0x18: addq $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor.1) pid=78370 stat=onproc
flags process=0 proc=4000000<THREAD>
pri=24, usrpri=80, nice=20
forw=0xffffffffffffffff, list=0xffff800020ad6290,0xffff800020ad78d8
process=0xffff800020af5548 user=0xffff800021b9c000,
vmspace=0xfffffd807f000a10
estcpu=36, cpticks=0, pctcpu=0.0
user=0, sys=0, intr=0
ddb{1}> ps
PID TID PPID UID S FLAGS WAIT COMMAND
55879 431531 64348 0 2 0 syz-executor.1
*55879 78370 64348 0 7 0x4000000 syz-executor.1
55879 320271 64348 0 2 0x4000000 syz-executor.1
64348 474796 33720 0 2 0x482 syz-executor.1
67480 185309 33720 0 7 0x482 syz-executor.0
33720 260543 23198 0 3 0x82 thrsleep syz-fuzzer
33720 489781 23198 0 3 0x4000082 thrsleep syz-fuzzer
33720 78200 23198 0 3 0x4000082 thrsleep syz-fuzzer
33720 161965 23198 0 3 0x4000082 thrsleep syz-fuzzer
33720 141384 23198 0 3 0x4000082 thrsleep syz-fuzzer
33720 519581 23198 0 3 0x4000082 thrsleep syz-fuzzer
33720 512695 23198 0 3 0x4000082 thrsleep syz-fuzzer
33720 158384 23198 0 3 0x4000082 thrsleep syz-fuzzer
33720 404889 23198 0 3 0x4000082 thrsleep syz-fuzzer
33720 142332 23198 0 3 0x4000082 kqread syz-fuzzer
23198 130020 92876 0 3 0x10008a pause ksh
92876 250118 80233 0 3 0x92 select sshd
2803 514016 1 0 3 0x100083 ttyin getty
80233 134070 1 0 3 0x80 select sshd
6265 86694 12830 74 3 0x100092 bpf pflogd
12830 20143 1 0 3 0x80 netio pflogd
8548 41518 81326 73 3 0x100090 kqread syslogd
81326 371028 1 0 3 0x100082 netio syslogd
49434 416768 1 77 3 0x100090 poll dhclient
50265 99865 1 0 3 0x80 poll dhclient
67315 78448 0 0 3 0x14200 pgzero zerothread
97953 95074 0 0 3 0x14200 aiodoned aiodoned
96855 294954 0 0 3 0x14200 syncer update
89919 247955 0 0 3 0x14200 cleaner cleaner
93711 152504 0 0 3 0x14200 reaper reaper
55507 249189 0 0 3 0x14200 pgdaemon pagedaemon
56428 152767 0 0 3 0x14200 bored crynlk
32059 104193 0 0 3 0x14200 bored crypto
40733 73955 0 0 3 0x40014200 acpi0 acpi0
29528 376208 0 0 3 0x40014200 idle1
92462 411510 0 0 3 0x14200 bored softnet
11034 332684 0 0 3 0x14200 bored systqmp
52432 340688 0 0 3 0x14200 bored systq
71296 506974 0 0 3 0x40014200 bored softclock
95824 226795 0 0 3 0x40014200 idle0
44803 359507 0 0 3 0x14200 bored smr
1 133455 0 0 3 0x82 wait init
0 0 -1 0 3 0x10200 scheduler swapper
ddb{1}> show all locks
Process 55879 (syz-executor.1) thread 0xffff800020ad6018 (78370)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff82655c30)
#0 witness_lock+0x52e sys/kern/subr_witness.c:1163
#1 __mp_acquire_count+0x51 sys/kern/kern_lock.c:227
#2 mi_switch+0x392 sys/kern/sched_bsd.c:434
#3 sleep_finish+0x113 sys/kern/kern_synch.c:388
#4 sleep_finish_all+0x32 sleep_finish_timeout sys/kern/kern_synch.c:417
[inline]
#4 sleep_finish_all+0x32 sys/kern/kern_synch.c:183
#5 tsleep+0x1cc sys/kern/kern_synch.c:153
#6 kqueue_scan+0x326 sys/kern/kern_event.c:835
#7 sys_kevent+0x48b sys/kern/kern_event.c:569
#8 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline]
#8 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555
#9 Xsyscall+0x128
ddb{1}> show malloc
Type InUse MemUse HighUse Limit Requests Type Lim
devbuf 9473 6406K 6415K 78643K 11402 0
pcb 16 8K 9K 78643K 7403 0
rtable 105 3K 3K 78643K 203 0
ifaddr 44 10K 10K 78643K 45 0
counters 39 33K 33K 78643K 39 0
ioctlops 0 0K 4K 78643K 2091 0
iov 0 0K 12K 78643K 208 0
mount 1 1K 1K 78643K 1 0
vnodes 1220 77K 77K 78643K 1851 0
UFS quota 1 32K 32K 78643K 1 0
UFS mount 5 36K 36K 78643K 5 0
shm 2 1K 9K 78643K 584 0
VM map 2 1K 1K 78643K 2 0
sem 12 0K 0K 78643K 761 0
dirhash 12 2K 2K 78643K 12 0
ACPI 1809 196K 290K 78643K 12766 0
file desc 5 13K 25K 78643K 10467 0
sigio 0 0K 0K 78643K 274 0
proc 60 63K 83K 78643K 439 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 37 175K 175K 78643K 37 0
exec 0 0K 1K 78643K 207 0
pfkey data 0 0K 1K 78643K 7 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 120 70K 70K 78643K 23636 0
UVM aobj 130 4K 4K 78643K 130 0
memdesc 1 4K 4K 78643K 1 0
crypto data 1 1K 1K 78643K 1 0
ip6_options 0 0K 0K 78643K 17 0
NDP 6 0K 0K 78643K 10 0
temp 111 3026K 3090K 78643K 25172 0
kqueue 1 0K 0K 78643K 43 0
SYN cache 2 16K 16K 78643K 2 0
ddb{1}> 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 80 21 0 19 1 0 1 1 0
8 0
rtentry 112 45 0 1 2 0 2 2 0
8 0
unpcb 120 10737 0 10727 5 4 1 2 0
8 0
syncache 264 4 0 4 1 1 0 1 0
8 0
sackhl 24 1 0 1 1 1 0 1 0
8 0
tcpcb 544 135 0 131 1 0 1 1 0
8 0
inpcb 280 7646 0 7636 15 13 2 3 0
8 1
nd6 48 4 0 0 1 0 1 1 0
8 0
pkpcb 40 8 0 8 1 1 0 1 0
8 0
pfosfp 40 846 0 423 5 0 5 5 0
8 0
pfosfpen 112 1428 0 714 21 0 21 21 0
8 0
pfstitem 24 11 0 9 1 0 1 1 0
8 0
pfstkey 112 11 0 9 1 0 1 1 0
8 0
pfstate 328 11 0 9 1 0 1 1 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 256 212 0 0 14 0 14 14 0
8 0
art_table 32 213 0 0 2 0 2 2 0
8 0
art_node 16 44 0 4 1 0 1 1 0
8 0
sysvmsgpl 40 133 0 133 4 4 0 1 0
8 0
semapl 112 759 0 749 1 0 1 1 0
8 0
shmpl 112 128 0 0 4 0 4 4 0
8 0
dirhash 1024 17 0 0 3 0 3 3 0
8 0
dino1pl 128 12073 0 10665 46 0 46 46 0
8 0
ffsino 272 12073 0 10665 95 0 95 95 0
8 0
nchpl 144 24439 0 22827 61 0 61 61 0
8 0
uvmvnodes 72 5926 0 0 108 0 108 108 0
8 0
vnodes 208 5926 0 0 312 0 312 312 0
8 0
namei 1024 67354 0 67354 1 0 1 1 0
8 1
percpumem 16 30 0 0 1 0 1 1 0
8 0
vcpupl 1984 6 0 1 1 0 1 1 0
8 0
vmpool 560 43 0 38 1 0 1 1 0
8 0
scxspl 192 67873 0 67873 8 7 1 7 0
8 1
plimitpl 152 64 0 56 1 0 1 1 0
8 0
sigapl 432 10666 0 10651 3 1 2 3 0
8 0
futexpl 56 75510 0 75510 1 0 1 1 0
8 1
knotepl 112 189 0 169 1 0 1 1 0
8 0
kqueuepl 104 341 0 338 1 0 1 1 0
8 0
pipepl 112 3826 0 3807 1 0 1 1 0
8 0
fdescpl 488 10667 0 10651 3 0 3 3 0
8 0
filepl 152 50796 0 50692 13 8 5 6 0
8 1
lockfpl 104 1002 0 1001 1 0 1 1 0
8 0
lockfspl 48 462 0 461 1 0 1 1 0
8 0
sessionpl 112 18 0 7 1 0 1 1 0
8 0
pgrppl 48 177 0 166 1 0 1 1 0
8 0
ucredpl 96 6324 0 6315 1 0 1 1 0
8 0
zombiepl 144 10651 0 10650 1 0 1 1 0
8 0
processpl 904 10682 0 10650 4 0 4 4 0
8 0
procpl 632 22774 0 22731 8 4 4 5 0
8 0
sockpl 384 18681 0 18659 22 18 4 6 0
8 1
mcl64k 65536 10 0 0 2 0 2 2 0
8 0
mcl16k 16384 16 0 0 2 0 2 2 0
8 0
mcl12k 12288 25 0 0 2 0 2 2 0
8 0
mcl9k 9216 21 0 0 2 1 1 2 0
8 0
mcl8k 8192 17 0 0 3 0 3 3 0
8 0
mcl4k 4096 17 0 0 3 0 3 3 0
8 0
mcl2k2 2112 10 0 0 1 0 1 1 0
8 0
mcl2k 2048 143 0 0 14 2 12 14 0
8 0
mtagpl 80 1 0 0 1 0 1 1 0
8 0
mbufpl 256 361 0 0 12 0 12 12 0
8 0
bufpl 280 16711 0 9641 506 0 506 506 0
8 0
anonpl 16 626834 0 622530 39 10 29 35 0 125
10
amapchunkpl 152 35984 0 35888 19 14 5 18 0
158 0
amappl16 192 45735 0 45532 26 14 12 22 0
8 1
amappl15 184 60 0 56 1 0 1 1 0
8 0
amappl14 176 36 0 33 1 0 1 1 0
8 0
amappl12 160 18 0 16 1 0 1 1 0
8 0
amappl11 152 63 0 48 1 0 1 1 0
8 0
amappl10 144 5272 0 5265 1 0 1 1 0
8 0
amappl9 136 5780 0 5776 1 0 1 1 0
8 0
amappl8 128 5344 0 5318 1 0 1 1 0
8 0
amappl7 120 5356 0 5344 1 0 1 1 0
8 0
amappl6 112 55 0 50 1 0 1 1 0
8 0
amappl5 104 211 0 195 1 0 1 1 0
8 0
amappl4 96 10962 0 10932 1 0 1 1 0
8 0
amappl3 88 1133 0 1125 1 0 1 1 0
8 0
amappl2 80 84586 0 84510 3 1 2 3 0
8 0
amappl1 72 183787 0 183342 24 14 10 20 0
8 0
amappl 80 23025 0 22981 3 1 2 2 0
84 0
dma4096 4096 1 0 1 1 1 0 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 64 129 0 0 3 0 3 3 0
8 0
uaddrrnd 24 10710 0 10689 1 0 1 1 0
8 0
uaddrbest 32 2 0 0 1 0 1 1 0
8 0
uaddr 24 10710 0 10689 1 0 1 1 0
8 0
vmmpekpl 168 48342 0 48308 3 1 2 2 0
8 0
vmmpepl 168 1191954 0 1190572 107 37 70 82 0
357 7
vmsppl 368 10709 0 10689 3 1 2 3 0
8 0
pdppl 4096 21427 0 21383 6 0 6 6 0
8 0
pvpl 32 1914199 0 1906688 178 82 96 118 0 265
33
pmappl 232 10709 0 10689 3 1 2 2 0
8 0
extentpl 40 46 0 29 1 0 1 1 0
8 0
phpool 112 168 0 6 5 0 5 5 0
8 0


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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Anton Lindqvist

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Jan 26, 2020, 5:00:54 AM1/26/20
to syzbot, syzkaller-o...@googlegroups.com
#syz dup: kqueue: knote !ACTIVE
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