assert "rt->rt_ifa->ifa_ifp != NULL" failed: file "panic: kernel diagnostic assertion "!_kernel_lock_held()" failed in k

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 29c780a8 regen
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=13e700a7600000
kernel config: https://syzkaller.appspot.com/x/.config?x=26ca0a9c07f16a3a
dashboard link: https://syzkaller.appspot.com/bug?extid=b0875d3256b7c68aa7ee

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+b0875d...@syzkaller.appspotmail.com

panic: kernel diagnostic assertion "rt->rt_ifa->ifa_ifp != NULL" failed:
file "panic: kernel diagnostic assertion "!_kernel_lock_held()" failed:
file "/syzkaller/managers/multicore/kernel/sys/kern/kern_fork.c", line 690
Stopped at db_enter+0x18: addq $0x8,%rsp
TID PID UID PRFLAGS PFLAGS CPU COMMAND
287033 63720 0 0 0x4000000 0 syz-executor.1
* 55440 48510 0 0 0x4000000 1 syz-executor.0
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic() at panic+0x15c sys/kern/subr_prf.c:207
__assert(ffffffff82207051,ffffffff821f613e,2b2,ffffffff821d67e2) at
__assert+0x2b sys/kern/subr_prf.c:154
proc_trampoline_mp() at proc_trampoline_mp+0x123
end trace frame: 0x0, count: 11
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
kernel diagnostic assertion "rt->rt_ifa->ifa_ifp != NULL" failed:
file "/syzkaller/managers/multicore/kernel/sys/net/route.c", line 848
ddb{1}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic() at panic+0x15c sys/kern/subr_prf.c:207
__assert(ffffffff82207051,ffffffff821f613e,2b2,ffffffff821d67e2) at
__assert+0x2b sys/kern/subr_prf.c:154
proc_trampoline_mp() at proc_trampoline_mp+0x123
end trace frame: 0x0, count: -4
ddb{1}> show registers
rdi 0
rsi 0x1
rbp 0xffff800023dc7410
rbx 0xffff800023dc74c0
rdx 0xffff800020ab0c70
rcx 0
rax 0
r8 0xffffffff812be63f kprintf+0x16f
r9 0x1
r10 0x25
r11 0xcfbc58d6946af996
r12 0x3000000008
r13 0xffff800023dc7420
r14 0x104
r15 0x1
rip 0xffffffff8101a1f8 db_enter+0x18
cs 0x8
rflags 0x246
rsp 0xffff800023dc7400
ss 0x10
db_enter+0x18: addq $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor.0) pid=55440 stat=onproc
flags process=0 proc=4000000<THREAD>
pri=86, usrpri=86, nice=20
forw=0xffffffffffffffff, list=0xffff800020ab1b40,0xffff800020a5f8c8
process=0xffff800020a8b890 user=0xffff800023dc2000,
vmspace=0xfffffd807f00bcf0
estcpu=36, cpticks=1, pctcpu=0.0
user=0, sys=1, intr=0
ddb{1}> ps
PID TID PPID UID S FLAGS WAIT COMMAND
63720 521120 21965 0 2 0 syz-executor.1
63720 287033 21965 0 7 0x4000000 syz-executor.1
48510 105778 77895 0 2 0 syz-executor.0
48510 304893 77895 0 3 0x4000080 netcon2 syz-executor.0
*48510 55440 77895 0 7 0x4000000 syz-executor.0
48510 284609 77895 0 2 0x4000000 syz-executor.0
77895 477433 6353 0 3 0x82 nanosleep syz-executor.0
21965 422675 6353 0 3 0x82 nanosleep syz-executor.1
12213 75583 0 0 3 0x14200 acct acct
43731 131331 0 0 3 0x14200 bored sosplice
6353 131128 43992 0 3 0x82 thrsleep syz-fuzzer
6353 53565 43992 0 3 0x4000082 thrsleep syz-fuzzer
6353 203083 43992 0 3 0x4000082 thrsleep syz-fuzzer
6353 463526 43992 0 3 0x4000082 thrsleep syz-fuzzer
6353 5009 43992 0 3 0x4000082 thrsleep syz-fuzzer
6353 206143 43992 0 3 0x4000082 kqread syz-fuzzer
6353 321407 43992 0 3 0x4000082 thrsleep syz-fuzzer
6353 263311 43992 0 3 0x4000082 thrsleep syz-fuzzer
6353 56715 43992 0 3 0x4000082 thrsleep syz-fuzzer
6353 495158 43992 0 3 0x4000082 thrsleep syz-fuzzer
43992 484008 52843 0 3 0x10008a pause ksh
52843 399006 87315 0 3 0x92 select sshd
85201 331168 1 0 3 0x100083 ttyin getty
87315 330194 1 0 3 0x80 select sshd
97832 288650 79538 74 3 0x100092 bpf pflogd
79538 406374 1 0 3 0x80 netio pflogd
51605 246852 49550 73 3 0x100090 kqread syslogd
49550 488146 1 0 3 0x100082 netio syslogd
85436 407219 1 77 3 0x100090 poll dhclient
23603 515452 1 0 3 0x80 poll dhclient
49644 456463 0 0 2 0x14200 zerothread
78837 17747 0 0 3 0x14200 aiodoned aiodoned
2550 239365 0 0 3 0x14200 syncer update
35800 70166 0 0 3 0x14200 cleaner cleaner
58254 149780 0 0 3 0x14200 reaper reaper
64284 130433 0 0 3 0x14200 pgdaemon pagedaemon
39027 32759 0 0 3 0x14200 bored crynlk
32433 164739 0 0 3 0x14200 bored crypto
12224 33641 0 0 3 0x40014200 acpi0 acpi0
84394 355316 0 0 3 0x40014200 idle1
29314 267574 0 0 3 0x14200 bored softnet
89522 141831 0 0 3 0x14200 bored systqmp
81106 265780 0 0 3 0x14200 bored systq
78044 160465 0 0 3 0x40014200 bored softclock
65652 185248 0 0 3 0x40014200 idle0
7376 368840 0 0 3 0x14200 bored smr
1 473745 0 0 3 0x82 wait init
0 0 -1 0 3 0x10200 scheduler swapper
ddb{1}> show all locks
Process 63720 (syz-executor.1) thread 0xffff800020ab1b40 (287033)
exclusive rwlock netlock r = 0 (0xffffffff824b9ff8)
#0 witness_lock+0x52e sys/kern/subr_witness.c:1163
#1 solock+0x5a sys/kern/uipc_socket2.c:282
#2 sys_connect+0x6b sys/kern/uipc_syscalls.c:362
#3 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline]
#3 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555
#4 Xsyscall+0x128
exclusive kernel_lock &kernel_lock r = 1 (0xffffffff82646968)
#0 witness_lock+0x52e sys/kern/subr_witness.c:1163
#1 syscall+0x400 mi_syscall sys/sys/syscall_mi.h:83 [inline]
#1 syscall+0x400 sys/arch/amd64/amd64/trap.c:555
#2 Xsyscall+0x128
ddb{1}> show malloc
Type InUse MemUse HighUse Limit Requests Type Lim Kern Lim
devbuf 9594 6453K 7965K 78643K 15474 0 0
pcb 13 10K 12K 78643K 465 0 0
rtable 113 13K 15K 78643K 1554 0 0
ifaddr 86 18K 18K 78643K 464 0 0
counters 39 33K 33K 78643K 39 0 0
ioctlops 0 0K 4K 78643K 1563 0 0
iov 0 0K 24K 78643K 365 0 0
mount 1 1K 1K 78643K 1 0 0
vnodes 1227 77K 78K 78643K 3364 0 0
UFS quota 1 32K 32K 78643K 1 0 0
UFS mount 5 36K 36K 78643K 5 0 0
shm 2 1K 9K 78643K 156 0 0
VM map 9 4K 5K 78643K 21 0 0
sem 12 0K 0K 78643K 481 0 0
dirhash 12 2K 2K 78643K 12 0 0
ACPI 1808 196K 290K 78643K 12765 0 0
file desc 6 17K 25K 78643K 2261 0 0
sigio 0 0K 0K 78643K 30 0 0
proc 62 63K 95K 78643K 1135 0 0
subproc 32 2K 2K 78643K 255 0 0
NFS srvsock 1 0K 0K 78643K 1 0 0
NFS daemon 1 16K 16K 78643K 1 0 0
ip_moptions 0 0K 0K 78643K 192 0 0
in_multi 30 2K 2K 78643K 298 0 0
ether_multi 1 0K 0K 78643K 31 0 0
mrt 0 0K 0K 78643K 14 0 0
ISOFS mount 1 32K 32K 78643K 1 0 0
MSDOSFS mount 1 16K 16K 78643K 1 0 0
ttys 150 662K 662K 78643K 150 0 0
exec 0 0K 1K 78643K 568 0 0
pagedep 1 8K 8K 78643K 1 0 0
inodedep 1 32K 32K 78643K 1 0 0
newblk 1 0K 0K 78643K 1 0 0
VM swap 7 26K 26K 78643K 7 0 0
UVM amap 134 72K 72K 78643K 9423 0 0
UVM aobj 130 4K 4K 78643K 132 0 0
memdesc 1 4K 4K 78643K 1 0 0
crypto data 1 1K 1K 78643K 1 0 0
ip6_options 0 0K 0K 78643K 508 0 0
NDP 21 0K 0K 78643K 141 0 0
temp 228 3557K 3644K 78643K 79822 0 0
kqueue 0 0K 0K 78643K 10 0 0
SYN cache 2 16K 16K 78643K 2 0 0
ddb{1}> show all pools
Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg
Idle
arp 64 56 0 51 1 0 1 1 0
8 0
plcache 128 20 0 0 1 0 1 1 0
8 0
rtpcb 80 168 0 166 1 0 1 1 0
8 0
rtentry 112 281 0 242 2 0 2 2 0
8 0
unpcb 120 1113 0 1102 2 1 1 2 0
8 0
syncache 264 20 0 20 6 6 0 1 0
8 0
tcpqe 32 48 0 48 5 5 0 1 0
8 0
tcpcb 544 1405 0 1396 2 1 1 2 0
8 0
inpcb 280 3424 0 3412 26 24 2 13 0
8 1
rttmr 72 5 0 4 2 1 1 1 0
8 0
nd6 48 36 0 33 2 1 1 1 0
8 0
pkpcb 40 9 0 9 4 4 0 1 0
8 0
ppxss 1128 58 0 58 13 12 1 1 0
8 1
pffrag 232 71 0 69 11 10 1 1 0
482 0
pffrnode 88 70 0 69 11 10 1 1 0
8 0
pffrent 40 2404 0 2372 10 9 1 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 24 197 0 164 1 0 1 1 0
8 0
pfstkey 112 197 0 164 2 0 2 2 0
8 0
pfstate 328 197 0 164 5 0 5 5 0
8 0
pfrule 1360 21 0 16 2 1 1 2 0
8 0
art_heap8 4096 15 0 14 7 6 1 3 0
8 0
art_heap4 256 1177 0 953 25 9 16 16 0
8 1
art_table 32 1192 0 967 4 1 3 3 0
8 0
art_node 16 279 0 243 1 0 1 1 0
8 0
sysvmsgpl 40 13 0 7 1 0 1 1 0
8 0
semupl 112 2 0 2 2 2 0 1 0
8 0
semapl 112 477 0 467 1 0 1 1 0
8 0
shmpl 112 130 0 2 4 0 4 4 0
8 0
dirhash 1024 17 0 0 3 0 3 3 0
8 0
dino1pl 128 5000 0 3599 46 0 46 46 0
8 0
ffsino 272 5000 0 3599 94 0 94 94 0
8 0
nchpl 144 9762 0 9276 61 41 20 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 34753 0 34753 1 0 1 1 0
8 1
percpumem 16 30 0 0 1 0 1 1 0
8 0
vcpupl 1984 7 0 0 1 0 1 1 0
8 0
vmpool 552 19 0 12 1 0 1 1 0
8 0
scsiplug 64 3 0 3 3 3 0 1 0
8 0
scxspl 192 25478 0 25478 24 23 1 7 0
8 1
plimitpl 152 189 0 181 1 0 1 1 0
8 0
sigapl 432 2422 0 2406 3 1 2 3 0
8 0
futexpl 56 53773 0 53773 1 0 1 1 0
8 1
knotepl 112 612 0 593 3 2 1 2 0
8 0
kqueuepl 104 549 0 547 2 1 1 2 0
8 0
pipepl 112 1344 0 1325 5 4 1 2 0
8 0
fdescpl 488 2423 0 2406 3 0 3 3 0
8 0
filepl 152 24383 0 24280 28 23 5 14 0
8 0
lockfpl 104 626 0 625 1 0 1 1 0
8 0
lockfspl 48 224 0 223 1 0 1 1 0
8 0
sessionpl 112 31 0 20 1 0 1 1 0
8 0
pgrppl 48 49 0 38 1 0 1 1 0
8 0
ucredpl 96 6881 0 6872 1 0 1 1 0
8 0
zombiepl 144 2406 0 2406 1 0 1 1 0
8 1
processpl 896 2440 0 2406 4 0 4 4 0
8 0
procpl 632 7967 0 7920 6 1 5 5 0
8 1
srpgc 64 21 0 21 8 8 0 1 0
8 0
sosppl 128 44 0 43 8 7 1 1 0
8 0
sockpl 384 4758 0 4733 34 30 4 21 0
8 1
mcl64k 65536 266 0 0 34 14 20 34 0
8 1
mcl16k 16384 17 0 0 3 0 3 3 0
8 1
mcl12k 12288 18 0 0 2 0 2 2 0
8 0
mcl9k 9216 11 0 0 1 0 1 1 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 5 0 0 1 0 1 1 0
8 0
mcl2k 2048 172 0 0 21 1 20 21 0
8 0
mtagpl 80 44 0 0 1 0 1 1 0
8 0
mbufpl 256 956 0 0 49 1 48 48 0
8 0
bufpl 256 12296 0 5248 441 0 441 441 0
8 0
anonpl 16 289797 0 270851 177 99 78 93 0
124 0
amapchunkpl 152 18184 0 18067 46 40 6 13 0
158 0
amappl16 192 13309 0 12231 147 91 56 67 0
8 0
amappl15 184 80 0 77 1 0 1 1 0
8 0
amappl14 176 559 0 555 1 0 1 1 0
8 0
amappl13 168 455 0 455 3 3 0 1 0
8 0
amappl12 160 212 0 208 2 1 1 1 0
8 0
amappl11 152 266 0 250 1 0 1 1 0
8 0
amappl10 144 701 0 695 1 0 1 1 0
8 0
amappl9 136 804 0 798 1 0 1 1 0
8 0
amappl8 128 366 0 322 2 0 2 2 0
8 0
amappl7 120 794 0 785 1 0 1 1 0
8 0
amappl6 112 259 0 250 1 0 1 1 0
8 0
amappl5 104 472 0 456 1 0 1 1 0
8 0
amappl4 96 2442 0 2407 1 0 1 1 0
8 0
amappl3 88 1324 0 1317 1 0 1 1 0
8 0
amappl2 80 17949 0 17866 3 1 2 3 0
8 0
amappl1 72 64399 0 63939 25 15 10 20 0
8 0
amappl 80 8467 0 8421 2 0 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 17 0 17 1 1 0 1 0
8 0
aobjpl 64 131 0 2 3 0 3 3 0
8 0
uaddrrnd 24 2442 0 2406 1 0 1 1 0
8 0
uaddrbest 32 2 0 0 1 0 1 1 0
8 0
uaddr 24 2442 0 2406 1 0 1 1 0
8 0
vmmpekpl 168 24662 0 24625 3 1 2 2 0
8 0
vmmpepl 168 316046 0 313673 320 193 127 144 0 357
21
vmsppl 368 2422 0 2406 2 0 2 2 0
8 0
pdppl 4096 4891 0 4843 8 1 7 7 0
8 0
pvpl 32 800855 0 779106 350 168 182 218 0
265 1
pmappl 232 2441 0 2418 3 1 2 2 0
8 0
extentpl 40 41 0 26 1 0 1 1 0
8 0
phpool 112 700 0 36 20 0 20 20 0
8 0


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[Anton Lindqvist]

#syz dup: assert "rt->rt_ifa->ifa_ifp != NULL" failed in route.c