assert "rt->rt_ifa->ifa_ifp != NULL" failed: file "/syzkaller/managers/multpanic: kernel diagnostic assertion "!_kernel_

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 0bd8f658 memleak in error path; spotted by oss-fuzz, ok ma..
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=15837f10e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=26ca0a9c07f16a3a
dashboard link: https://syzkaller.appspot.com/bug?extid=7d36a2f77e5565c88505

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+7d36a2...@syzkaller.appspotmail.com

panic: kernel diagnostic assertion "rt->rt_ifa->ifa_ifp != NULL" failed:
file "/syzkaller/managers/multpanic: 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
255869 71971 0 0 0x4000000 0 syz-executor.0
*266095 71971 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(ffffffff82207fa4,ffffffff821f6416,2b2,ffffffff821d8bbd) 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(ffffffff82207fa4,ffffffff821f6416,2b2,ffffffff821d8bbd) 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 0xffff800021963870
rbx 0xffff800021963920
rdx 0xffff800020ace510
rcx 0
rax 0
r8 0xffffffff821395ef kprintf+0x16f
r9 0x1
r10 0x25
r11 0xa26507f901389220
r12 0x3000000008
r13 0xffff800021963880
r14 0x104
r15 0x1
rip 0xffffffff816aed08 db_enter+0x18
cs 0x8
rflags 0x246
rsp 0xffff800021963860
ss 0x10
db_enter+0x18: addq $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor.0) pid=266095 stat=onproc
flags process=0 proc=4000000<THREAD>
pri=82, usrpri=82, nice=20
forw=0xffffffffffffffff, list=0xffff800020aceef0,0xffffffff8266fc68
process=0xffff800020addc00 user=0xffff80002195e000,
vmspace=0xfffffd807f00b450
estcpu=32, cpticks=1, pctcpu=0.0
user=0, sys=1, intr=0
ddb{1}> ps
PID TID PPID UID S FLAGS WAIT COMMAND
71971 23856 45385 0 2 0 syz-executor.0
71971 255869 45385 0 7 0x4000000 syz-executor.0
71971 4696 45385 0 2 0x4000000 syz-executor.0
*71971 266095 45385 0 7 0x4000000 syz-executor.0
59197 241497 94450 0 2 0 syz-executor.1
59197 495961 94450 0 3 0x4000000 physio syz-executor.1
45385 166317 38585 0 3 0x82 nanosleep syz-executor.0
94450 131572 38585 0 3 0x82 nanosleep syz-executor.1
56982 107485 0 0 3 0x14200 acct acct
53114 426434 1 0 3 0x100083 ttyin getty
62536 381299 0 0 3 0x14200 bored sosplice
38585 259705 87945 0 3 0x82 thrsleep syz-fuzzer
38585 194573 87945 0 3 0x4000082 nanosleep syz-fuzzer
38585 99304 87945 0 3 0x4000082 thrsleep syz-fuzzer
38585 463224 87945 0 3 0x4000082 kqread syz-fuzzer
38585 191779 87945 0 3 0x4000082 thrsleep syz-fuzzer
38585 508797 87945 0 3 0x4000082 thrsleep syz-fuzzer
38585 144319 87945 0 3 0x4000082 thrsleep syz-fuzzer
38585 89298 87945 0 3 0x4000082 thrsleep syz-fuzzer
38585 302197 87945 0 3 0x4000082 thrsleep syz-fuzzer
38585 367331 87945 0 3 0x4000082 thrsleep syz-fuzzer
87945 213401 36780 0 3 0x10008a pause ksh
36780 255434 19519 0 3 0x92 select sshd
19519 348526 1 0 3 0x80 select sshd
45887 357632 33501 74 3 0x100092 bpf pflogd
33501 188769 1 0 3 0x80 netio pflogd
55969 159408 48767 73 3 0x100090 kqread syslogd
48767 442169 1 0 3 0x100082 netio syslogd
84060 152310 1 77 3 0x100090 poll dhclient
13646 95792 1 0 3 0x80 poll dhclient
2508 304008 0 0 2 0x14200 zerothread
27984 182095 0 0 3 0x14200 aiodoned aiodoned
72651 440669 0 0 3 0x14200 syncer update
65112 372574 0 0 3 0x14200 cleaner cleaner
7410 453901 0 0 3 0x14200 reaper reaper
82761 227394 0 0 3 0x14200 pgdaemon pagedaemon
25005 330267 0 0 3 0x14200 bored crynlk
25167 185368 0 0 3 0x14200 bored crypto
24009 378821 0 0 3 0x40014200 acpi0 acpi0
37866 3362 0 0 3 0x40014200 idle1
30425 138079 0 0 3 0x14200 bored softnet
77207 330469 0 0 3 0x14200 bored systqmp
47659 113576 0 0 3 0x14200 bored systq
19189 750 0 0 3 0x40014200 bored softclock
33582 511342 0 0 3 0x40014200 idle0
67506 478350 0 0 3 0x14200 bored smr
1 420900 0 0 3 0x82 wait init
0 0 -1 0 3 0x10200 scheduler swapper
ddb{1}> show all locks
Process 71971 (syz-executor.0) thread 0xffff800020acfb48 (255869)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff82640b98)
#0 witness_lock+0x52e sys/kern/subr_witness.c:1163
#1 rt_clone+0x5c sys/net/route.c:266
#2 rtalloc_mpath+0xba rt_match sys/net/route.c:244 [inline]
#2 rtalloc_mpath+0xba sys/net/route.c:359
#3 ip_output+0x4f2 sys/netinet/ip_output.c:204
#4 rip_output+0x252 sys/netinet/raw_ip.c:289
#5 rip_usrreq+0x46a sys/netinet/raw_ip.c:538
#6 sosend+0x645 sys/kern/uipc_socket.c:524
#7 dofilewritev+0x1b7 sys/kern/sys_generic.c:364
#8 sys_write+0x83 sys/kern/sys_generic.c:284
#9 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline]
#9 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555
#10 Xsyscall+0x128
exclusive rwlock netlock r = 0 (0xffffffff82486268)
#0 witness_lock+0x52e sys/kern/subr_witness.c:1163
#1 solock+0x5a sys/kern/uipc_socket2.c:282
#2 sosend+0x51b sys/kern/uipc_socket.c:512
#3 dofilewritev+0x1b7 sys/kern/sys_generic.c:364
#4 sys_write+0x83 sys/kern/sys_generic.c:284
#5 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline]
#5 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555
#6 Xsyscall+0x128
Process 59197 (syz-executor.1) thread 0xffff800020acf8d0 (495961)
shared rwlock vmmaplk r = 0 (0xfffffd807f00b748)
#0 witness_lock+0x52e sys/kern/subr_witness.c:1163
#1 uvm_vslock_device+0x11e sys/uvm/uvm_glue.c:174
#2 physio+0x26a sys/kern/kern_physio.c:139
#3 spec_read+0xf1 sys/kern/spec_vnops.c:223
#4 VOP_READ+0xbf sys/kern/vfs_vops.c:248
#5 vn_read+0x124 sys/kern/vfs_vnops.c:378
#6 dofilereadv+0x1a2 sys/kern/sys_generic.c:236
#7 sys_preadv+0xb8 sys/kern/vfs_syscalls.c:3207
#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 Kern Lim
devbuf 9566 6441K 8893K 78643K 19418 0 0
pcb 13 10K 12K 78643K 296 0 0
rtable 122 9K 9K 78643K 1312 0 0
ifaddr 77 17K 17K 78643K 387 0 0
counters 39 33K 33K 78643K 39 0 0
ioctlops 0 0K 4K 78643K 1536 0 0
iov 0 0K 32K 78643K 234 0 0
mount 1 1K 1K 78643K 1 0 0
vnodes 1233 77K 78K 78643K 3866 0 0
UFS quota 1 32K 32K 78643K 1 0 0
UFS mount 5 36K 36K 78643K 5 0 0
shm 2 1K 5K 78643K 24 0 0
VM map 5 2K 3K 78643K 12 0 0
sem 12 0K 0K 78643K 640 0 0
dirhash 12 2K 2K 78643K 12 0 0
ACPI 1808 196K 290K 78643K 12765 0 0
file desc 6 17K 25K 78643K 1370 0 0
sigio 0 0K 0K 78643K 23 0 0
proc 61 63K 83K 78643K 848 0 0
subproc 32 2K 2K 78643K 153 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 105 0 0
in_multi 34 2K 2K 78643K 217 0 0
ether_multi 1 0K 0K 78643K 13 0 0
mrt 0 0K 0K 78643K 5 0 0
ISOFS mount 1 32K 32K 78643K 1 0 0
MSDOSFS mount 1 16K 16K 78643K 1 0 0
ttys 72 318K 318K 78643K 72 0 0
exec 0 0K 1K 78643K 462 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 129 55K 71K 78643K 5832 0 0
UVM aobj 69 4K 4K 78643K 79 0 0
memdesc 1 4K 4K 78643K 1 0 0
crypto data 1 1K 1K 78643K 1 0 0
ip6_options 0 0K 1K 78643K 319 0 0
NDP 17 0K 0K 78643K 126 0 0
temp 207 3560K 3628K 78643K 24063 0 0
kqueue 0 0K 0K 78643K 5 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 48 0 41 1 0 1 1 0
8 0
plcache 128 20 0 0 1 0 1 1 0
8 0
rtpcb 80 128 0 126 1 0 1 1 0
8 0
rtentry 112 229 0 181 2 0 2 2 0
8 0
unpcb 120 665 0 655 1 0 1 1 0
8 0
syncache 264 4 0 4 1 1 0 1 0
8 0
tcpqe 32 11 0 11 1 1 0 1 0
8 0
tcpcb 544 1134 0 1130 27 26 1 12 0
8 0
inpcb 280 3153 0 3143 19 17 2 9 0
8 1
rttmr 72 2 0 2 1 1 0 1 0
8 0
nd6 48 30 0 26 1 0 1 1 0
8 0
pkpcb 40 10 0 10 2 2 0 1 0
8 0
ppxss 1128 48 0 48 5 4 1 1 0
8 1
pffrag 232 49 0 49 3 2 1 1 0
482 1
pffrnode 88 49 0 49 3 2 1 1 0
8 1
pffrent 40 1385 0 1385 3 2 1 1 0
8 1
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 24 145 0 75 1 0 1 1 0
8 0
pfstkey 112 148 0 78 3 0 3 3 0
8 0
pfstate 328 148 0 78 7 0 7 7 0
8 0
pfrule 1360 21 0 16 2 1 1 2 0
8 0
art_heap8 4096 2 0 1 2 1 1 2 0
8 0
art_heap4 256 977 0 743 19 3 16 16 0
8 0
art_table 32 979 0 744 2 0 2 2 0
8 0
art_node 16 228 0 184 1 0 1 1 0
8 0
sysvmsgpl 40 34 0 17 1 0 1 1 0
8 0
semapl 112 638 0 628 1 0 1 1 0
8 0
shmpl 112 77 0 10 2 0 2 2 0
8 0
dirhash 1024 17 0 0 3 0 3 3 0
8 0
dino1pl 128 3537 0 2124 46 0 46 46 0
8 0
ffsino 272 3537 0 2124 95 0 95 95 0
8 0
nchpl 144 6016 0 5549 61 41 20 61 0
8 0
uvmvnodes 72 5870 0 0 107 0 107 107 0
8 0
vnodes 208 5870 0 0 309 0 309 309 0
8 0
namei 1024 20504 0 20504 1 0 1 1 0
8 1
percpumem 16 30 0 0 1 0 1 1 0
8 0
vcpupl 1984 3 0 0 1 0 1 1 0
8 0
vmpool 552 10 0 7 1 0 1 1 0
8 0
scsiplug 64 2 0 2 2 2 0 1 0
8 0
scxspl 192 19267 0 19266 14 13 1 7 0
8 0
plimitpl 152 131 0 123 1 0 1 1 0
8 0
sigapl 432 1550 0 1534 3 1 2 3 0
8 0
futexpl 56 34293 0 34293 1 0 1 1 0
8 1
knotepl 112 340 0 321 1 0 1 1 0
8 0
kqueuepl 104 625 0 623 7 6 1 4 0
8 0
pipepl 112 1028 0 1009 4 3 1 2 0
8 0
fdescpl 488 1551 0 1534 3 0 3 3 0
8 0
filepl 152 14370 0 14265 25 19 6 14 0
8 1
lockfpl 104 489 0 488 1 0 1 1 0
8 0
lockfspl 48 162 0 161 1 0 1 1 0
8 0
sessionpl 112 26 0 15 1 0 1 1 0
8 0
pgrppl 48 47 0 36 1 0 1 1 0
8 0
ucredpl 96 1216 0 1207 1 0 1 1 0
8 0
zombiepl 144 1535 0 1535 1 0 1 1 0
8 1
processpl 896 1569 0 1535 4 0 4 4 0
8 0
procpl 632 4655 0 4608 5 0 5 5 0
8 0
srpgc 64 8 0 8 3 2 1 1 0
8 1
sosppl 128 9 0 9 4 3 1 1 0
8 1
sockpl 384 3982 0 3960 30 26 4 14 0
8 1
mcl64k 65536 27 0 0 3 0 3 3 0
8 0
mcl16k 16384 7 0 0 1 0 1 1 0
8 0
mcl12k 12288 17 0 0 2 0 2 2 0
8 0
mcl9k 9216 9 0 0 1 0 1 1 0
8 0
mcl8k 8192 14 0 0 2 0 2 2 0
8 0
mcl4k 4096 16 0 0 2 0 2 2 0
8 0
mcl2k2 2112 3 0 0 1 0 1 1 0
8 0
mcl2k 2048 165 0 0 20 1 19 20 0
8 0
mtagpl 80 27 0 0 1 0 1 1 0
8 0
mbufpl 256 516 0 0 30 0 30 30 0
8 0
bufpl 256 10520 0 3471 441 0 441 441 0
8 0
anonpl 16 182262 0 167471 121 29 92 93 0 124
15
amapchunkpl 152 11135 0 10993 31 24 7 14 0
158 1
amappl16 192 8011 0 6979 96 37 59 64 0
8 7
amappl14 176 696 0 692 1 0 1 1 0
8 0
amappl13 168 70 0 70 1 1 0 1 0
8 0
amappl12 160 240 0 240 2 1 1 1 0
8 1
amappl11 152 321 0 306 1 0 1 1 0
8 0
amappl10 144 25 0 18 1 0 1 1 0
8 0
amappl9 136 793 0 783 1 0 1 1 0
8 0
amappl8 128 379 0 339 2 0 2 2 0
8 0
amappl7 120 76 0 66 1 0 1 1 0
8 0
amappl6 112 319 0 309 1 0 1 1 0
8 0
amappl5 104 435 0 421 1 0 1 1 0
8 0
amappl4 96 1575 0 1542 1 0 1 1 0
8 0
amappl3 88 1023 0 1017 1 0 1 1 0
8 0
amappl2 80 11116 0 11034 3 1 2 3 0
8 0
amappl1 72 44550 0 44086 26 16 10 20 0
8 0
amappl 80 5050 0 5001 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 78 0 10 2 0 2 2 0
8 0
uaddrrnd 24 1561 0 1534 1 0 1 1 0
8 0
uaddrbest 32 2 0 0 1 0 1 1 0
8 0
uaddr 24 1561 0 1534 1 0 1 1 0
8 0
vmmpekpl 168 16679 0 16644 2 0 2 2 0
8 0
vmmpepl 168 204529 0 202224 191 56 135 135 0 357
31
vmsppl 368 1550 0 1534 2 0 2 2 0
8 0
pdppl 4096 3129 0 3085 6 0 6 6 0
8 0
pvpl 32 541264 0 523431 258 44 214 217 0 265
37
pmappl 232 1560 0 1541 3 1 2 2 0
8 0
extentpl 40 41 0 26 1 0 1 1 0
8 0
phpool 112 658 0 34 18 0 18 18 0
8 0


---
This bug is generated by a bot. It may contain errors.
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[Greg Steuck]

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