uvm_fault: km_free (2)

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Dec 7, 2023, 2:27:31 PM12/7/23

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Hello,

syzbot found the following issue on:

HEAD commit: 0d0a919f69d9 Add tests that create and delete cloned route..
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=1652230ee80000
kernel config: https://syzkaller.appspot.com/x/.config?x=7058272de1526588
dashboard link: https://syzkaller.appspot.com/bug?extid=bcfb7e93c9db34608a33

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e1b0b6c80b9e/disk-0d0a919f.raw.xz
bsd.gdb: https://storage.googleapis.com/syzbot-assets/f7bb7aab625e/bsd-0d0a919f.gdb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4724dca89b34/kernel-0d0a919f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bcfb7e...@syzkaller.appspotmail.com

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kernel: page fault trap, code=2
Stopped at km_free+0x128: movq $0,0(%rax)
TID PID UID PRFLAGS PFLAGS CPU COMMAND
*395848 22205 0 0x14000 0x200 0 systqmp
km_free(0,1000,ffffffff829d5d48,ffffffff829d5d60) at km_free+0x128 sys/uvm/uvm_km.c:866
pool_p_free(ffffffff82d84918,fffffd807e7b0f90) at pool_p_free+0x14b sys/kern/subr_pool.c:1012
pool_gc_pages(0) at pool_gc_pages+0x255 sys/kern/subr_pool.c:1583
taskq_thread(ffffffff82c01160) at taskq_thread+0xe5 sys/kern/kern_task.c:450
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{0}>
ddb{0}> set $lines = 0
ddb{0}> set $maxwidth = 0
ddb{0}> show panic
*cpu0: uvm_fault(0xffffffff82d87728, 0x0, 0, 2) -> e
ddb{0}> trace
km_free(0,1000,ffffffff829d5d48,ffffffff829d5d60) at km_free+0x128 sys/uvm/uvm_km.c:866
pool_p_free(ffffffff82d84918,fffffd807e7b0f90) at pool_p_free+0x14b sys/kern/subr_pool.c:1012
pool_gc_pages(0) at pool_gc_pages+0x255 sys/kern/subr_pool.c:1583
taskq_thread(ffffffff82c01160) at taskq_thread+0xe5 sys/kern/kern_task.c:450
end trace frame: 0x0, count: -4
ddb{0}> show registers
rdi 0x1000 __ALIGN_SIZE
rsi 0x28000000
rbp 0xffff800021177570
rbx 0x28000000000
rdx 0
rcx 0xffff800021158550
rax 0
r8 0
r9 0x1
r10 0x4545790d7e589de3
r11 0x345bce24c6da2c9b
r12 0
r13 0xffffffff829d5d48 kv_page
r14 0x1000 __ALIGN_SIZE
r15 0x1000 __ALIGN_SIZE
rip 0xffffffff819e2488 km_free+0x128
cs 0x8
rflags 0x10246 __ALIGN_SIZE+0xf246
rsp 0xffff8000211774f0
ss 0x10
km_free+0x128: movq $0,0(%rax)
ddb{0}> show proc
PROC (systqmp) tid=395848 pid=22205 tcnt=1 stat=onproc
flags process=14000<NOZOMBIE,SYSTEM> proc=200<SYSTEM>
runpri=32, usrpri=50, slppri=32, nice=20
wchan=0x0, wmesg=, ps_single=0x0
forw=0xffffffffffffffff, list=0xffff8000211587f8,0xffff800021158010
process=0xffff8000ffffc000 user=0xffff800021172000, vmspace=0xffffffff82d87728
estcpu=0, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0
ddb{0}> ps
PID TID PPID UID S FLAGS WAIT COMMAND
74336 416568 28386 0 3 0x82 piperd syz-executor.3
59375 215387 1 0 3 0x100083 ttyin getty
95170 260288 28386 0 3 0x82 piperd syz-executor.5
52796 416233 28386 0 3 0x82 piperd syz-executor.1
90251 62167 28386 0 3 0x82 piperd syz-executor.7
45645 126878 0 0 3 0x14200 acct acct
40748 57565 28386 0 3 0x82 wait syz-executor.2
70778 344492 28386 0 3 0x82 piperd syz-executor.4
31346 513946 28386 0 3 0x82 piperd syz-executor.6
67452 190833 0 0 3 0x14280 nfsidl nfsio
46167 395384 0 0 3 0x14280 nfsidl nfsio
33132 295687 0 0 3 0x14280 nfsidl nfsio
51194 183652 0 0 3 0x14280 nfsidl nfsio
93141 44386 0 0 3 0x14280 nfsidl nfsio
91169 286885 0 0 3 0x14280 nfsidl nfsio
27876 347006 0 0 3 0x14280 nfsidl nfsio
74532 140612 0 0 3 0x14280 nfsidl nfsio
12398 465649 0 0 3 0x14280 nfsidl nfsio
16556 334019 0 0 3 0x14280 nfsidl nfsio
44370 30883 0 0 3 0x14280 nfsidl nfsio
35898 287881 0 0 3 0x14280 nfsidl nfsio
43075 430717 0 0 3 0x14280 nfsidl nfsio
82330 304852 0 0 3 0x14280 nfsidl nfsio
77140 127994 0 0 3 0x14280 nfsidl nfsio
78296 481396 0 0 3 0x14280 nfsidl nfsio
78304 85467 0 0 3 0x14280 nfsidl nfsio
22743 499781 0 0 3 0x14280 nfsidl nfsio
97484 274342 0 0 3 0x14280 nfsidl nfsio
64454 328460 0 0 3 0x14280 nfsidl nfsio
37993 81581 0 0 3 0x14200 bored sosplice
72384 81701 28386 0 3 0x82 piperd syz-executor.0
28386 178826 98539 0 3 0x2000082 thrsleep syz-fuzzer
28386 213403 98539 0 3 0x6000082 thrsleep syz-fuzzer
28386 301239 98539 0 3 0x6000082 thrsleep syz-fuzzer
28386 491190 98539 0 3 0x6000082 wait syz-fuzzer
28386 12129 98539 0 3 0x6000082 thrsleep syz-fuzzer
28386 409881 98539 0 3 0x6000082 wait syz-fuzzer
28386 218704 98539 0 3 0x6000082 wait syz-fuzzer
28386 20361 98539 0 3 0x6000082 thrsleep syz-fuzzer
28386 95156 98539 0 3 0x6000082 wait syz-fuzzer
28386 40469 98539 0 3 0x6000082 thrsleep syz-fuzzer
28386 405981 98539 0 3 0x6000082 thrsleep syz-fuzzer
28386 283865 98539 0 3 0x6000082 kqread syz-fuzzer
28386 243552 98539 0 3 0x6000082 wait syz-fuzzer
28386 201285 98539 0 3 0x6000082 wait syz-fuzzer
28386 278282 98539 0 3 0x6000082 wait syz-fuzzer
28386 354916 98539 0 3 0x6000082 wait syz-fuzzer
98539 401629 48448 0 3 0x10008a sigsusp ksh
48448 125948 30642 0 3 0x9a kqread sshd
30642 367038 1 0 3 0x88 kqread sshd
3460 425629 91881 74 3 0x1100092 bpf pflogd
91881 417210 1 0 3 0x80 netio pflogd
43734 14617 81056 73 3 0x1100090 kqread syslogd
81056 288356 1 0 3 0x100082 netio syslogd
17736 373669 1 0 3 0x100080 kqread resolvd
70437 6473 78654 77 3 0x100092 kqread dhcpleased
34712 4958 78654 77 3 0x100092 kqread dhcpleased
78654 185248 1 0 3 0x80 kqread dhcpleased
67554 165584 0 0 3 0x14200 bored smr
48172 373112 0 0 3 0x14200 pgzero zerothread
58729 57375 0 0 3 0x14200 aiodoned aiodoned
84771 523459 0 0 3 0x14200 syncer update
93424 358022 0 0 3 0x14200 cleaner cleaner
37378 492118 0 0 3 0x14200 reaper reaper
54755 424251 0 0 3 0x14200 pgdaemon pagedaemon
61869 473667 0 0 3 0x14200 bored viomb
70350 252792 0 0 3 0x40014200 acpi0 acpi0
41461 438395 0 0 7 0x40014200 idle1
14566 403259 0 0 3 0x14200 bored softnet3
35854 309236 0 0 3 0x14200 bored softnet2
48255 321003 0 0 3 0x14200 bored softnet1
27352 163513 0 0 3 0x14200 bored softnet0
*22205 395848 0 0 7 0x14200 systqmp
20603 227501 0 0 3 0x14200 bored systq
65368 332398 0 0 3 0x14200 tmoslp softclockmp
79516 175709 0 0 3 0x40014200 tmoslp softclock
79803 194455 0 0 3 0x40014200 idle0
1 426354 0 0 3 0x80082 wait init
0 0 -1 0 3 0x10200 scheduler swapper
ddb{0}> show all locks
Process 22205 (systqmp) thread 0xffff800021158550 (395848)
ddb{0}> show malloc
Type InUse MemUse HighUse Limit Requests Type Lim
devbuf 10228 6508K 7572K 78643K 17670 0
pcb 13 16K 18K 78643K 1626 0
rtable 248 15K 15K 78643K 1643 0
pf 35 10K 10K 78643K 538 0
ifaddr 46 17K 18K 78643K 313 0
ifgroup 60 2K 2K 78643K 800 0
sysctl 3 0K 0K 78643K 5 0
counters 62 36K 36K 78643K 462 0
ioctlops 0 0K 4K 78643K 2075 0
iov 0 0K 24K 78643K 1637 0
mount 1 1K 1K 78643K 1 0
log 0 0K 0K 78643K 4 0
vnodes 1532 96K 96K 78643K 6678 0
UFS quota 1 32K 32K 78643K 1 0
UFS mount 5 36K 36K 78643K 5 0
shm 2 1K 13K 78643K 810 0
VM map 2 1K 1K 78643K 2 0
sem 12 0K 0K 78643K 1372 0
dirhash 12 2K 2K 78643K 57 0
ACPI 1697 195K 286K 78643K 12548 0
file desc 11 37K 74K 78643K 17444 0
sigio 0 0K 0K 78643K 338 0
proc 70 91K 115K 78643K 1884 0
subproc 104 6K 6K 78643K 425 0
NFS srvsock 1 0K 0K 78643K 1 0
NFS daemon 1 16K 16K 78643K 1 0
ip_moptions 0 0K 0K 78643K 783 0
in_multi 99 7K 7K 78643K 464 0
ether_multi 1 0K 0K 78643K 25 0
mrt 1 0K 0K 78643K 25 0
ISOFS mount 1 32K 32K 78643K 1 0
MSDOSFS mount 1 16K 16K 78643K 1 0
ttys 229 1023K 1023K 78643K 229 0
exec 0 0K 1K 78643K 2199 0
pfkey data 0 0K 0K 78643K 8 0
tdb 3 0K 0K 78643K 3 0
pagedep 1 8K 8K 78643K 1 0
inodedep 1 32K 32K 78643K 1 0
newblk 1 0K 0K 78643K 1 0
VM swap 8 62K 64K 78643K 10 0
UVM amap 518 619K 624K 78643K 171743 0
UVM aobj 131 4K 4K 78643K 134 0
memdesc 1 4K 4K 78643K 1 0
crypto data 1 1K 1K 78643K 1 0
ip6_options 0 0K 0K 78643K 506 0
NDP 13 0K 1K 78643K 267 0
temp 74 5920K 6048K 78643K 127513 0
kqueue 12 18K 26K 78643K 1110 0
SYN cache 2 824K 832K 78643K 3 0
ddb{0}> show all pools
Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
plcache 128 22 0 0 1 0 1 1 0 8 0
rtpcb 120 1399 0 1396 28 27 1 5 0 8 0
rtentry 112 418 0 304 4 0 4 4 0 8 0
unpcb 144 12116 0 12101 131 130 1 10 0 8 0
syncache 312 197 0 197 31 31 0 1 0 8 0
tcpqe 32 975 0 975 27 27 0 1 0 8 0
tcpcb 808 12253 0 12229 198 191 7 16 0 8 1
arp 120 59 0 41 1 0 1 1 0 8 0
ipq 40 7 0 7 2 2 0 1 0 8 0
ipqe 40 21 0 21 2 2 0 1 0 8 0
inpcb 368 22092 0 22065 226 218 8 19 0 8 3
nd6 136 98 0 70 2 0 2 2 0 8 0
pkpcb 40 25 0 25 8 8 0 1 0 8 0
kcovpl 48 27 0 19 1 0 1 1 0 8 0
ppxss 1256 76 0 76 16 15 1 1 0 8 1
pffrag 232 162 0 159 5 4 1 1 0 482 0
pffrnode 88 162 0 159 5 4 1 1 0 8 0
pffrent 40 1251 0 1248 4 3 1 1 0 8 0
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 24 521 0 509 1 0 1 1 0 8 0
pfstkey 128 521 0 509 2 0 2 2 0 8 0
pfstate 376 521 0 509 9 5 4 6 0 8 0
pfrule 1344 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 1400 0 915 33 2 31 32 0 8 0
art_table 32 1401 0 915 5 0 5 5 0 8 0
art_node 16 339 0 235 1 0 1 1 0 8 0
semapl 112 1364 0 1354 1 0 1 1 0 8 0
shmpl 112 131 0 3 4 0 4 4 0 8 0
dirhash 1024 47 0 30 3 0 3 3 0 8 0
dino2pl 256 24329 0 22797 97 0 97 97 0 8 0
ffsino 272 24329 0 22797 103 0 103 103 0 8 0
nchpl 144 51546 0 51016 63 41 22 63 0 8 0
uvmvnodes 80 23992 0 0 490 0 490 490 0 8 0
vnodes 216 23992 0 0 1333 0 1333 1333 0 8 0
namei 1024 178121 0 178121 12 11 1 3 0 8 1
percpumem 16 244 0 200 1 0 1 1 0 8 0
vcpupl 2048 269 0 1 34 0 34 34 0 8 0
vmpool 696 312 0 44 25 0 25 25 0 8 0
kstatmem 264 426 0 400 2 0 2 2 0 8 0
scxspl 216 149927 0 149927 38 37 1 8 1 8 1
plimitpl 152 1761 0 1745 1 0 1 1 0 8 0
sigapl 424 17772 0 17708 10 2 8 8 0 8 0
futexpl 64 165188 0 165188 5 4 1 1 0 8 1
knotepl 120 863 0 0 11 0 11 11 0 8 0
kqueuepl 216 2972 0 2964 58 57 1 7 0 8 0
pipepl 320 3723 0 3695 111 108 3 11 0 8 0
fdescpl 496 17727 0 17703 6 1 5 5 0 8 0
filepl 152 123135 0 122895 200 189 11 25 0 8 0
lockfpl 104 4892 0 4890 9 8 1 3 0 8 0
lockfspl 48 1542 0 1540 1 0 1 1 0 8 0
sessionpl 144 55 0 38 1 0 1 1 0 8 0
pgrppl 48 354 0 337 1 0 1 1 0 8 0
ucredpl 104 12592 0 12576 1 0 1 1 0 8 0
zombiepl 144 17709 0 17708 3 2 1 1 0 8 0
processpl 1072 17772 0 17708 6 1 5 5 0 8 0
procpl 680 48138 0 48059 20 11 9 10 0 8 0
sosppl 168 219 0 219 15 15 0 1 0 8 0
sockpl 488 35657 0 35612 591 577 14 37 0 8 3
mcl64k 65536 25 0 0 4 1 3 3 0 8 0
mcl16k 16384 25 0 0 3 0 3 3 0 8 0
mcl12k 12288 21 0 0 3 1 2 2 0 8 0
mcl9k 9216 17 0 0 2 0 2 2 0 8 0
mcl8k 8192 18 0 0 3 0 3 3 0 8 0
mcl4k 4096 33 0 0 4 1 3 3 0 8 0
mcl2k2 2112 11 0 0 1 0 1 1 0 8 0
mcl2k 2048 410 0 0 39 14 25 39 0 8 0
mtagpl 96 186 0 0 5 0 5 5 0 8 0
mbufpl 256 13824 0 0 828 0 828 828 0 8 0
bufpl 288 34292 0 27774 466 0 466 466 0 8 0
anonpl 24 1742592 0 1728201 262 147 115 163 0 186 0
amapchunkpl 152 545757 0 544958 191 143 48 67 0 158 8
amappl16 200 32847 0 32343 184 156 28 40 0 8 0
amappl15 192 17 0 17 2 2 0 1 0 8 0
amappl14 184 250 0 236 2 1 1 2 0 8 0
amappl13 176 23 0 22 2 1 1 1 0 8 0
amappl12 168 18719 0 18687 3 1 2 2 0 8 0
amappl11 160 56 0 41 1 0 1 1 0 8 0
amappl10 152 55 0 44 2 1 1 1 0 8 0
amappl9 144 398 0 398 34 34 0 1 0 8 0
amappl8 136 831 0 667 6 0 6 6 0 8 0
amappl7 128 315 0 286 3 1 2 3 0 8 0
amappl6 120 735 0 723 1 0 1 1 0 8 0
amappl5 112 454 0 442 1 0 1 1 0 8 0
amappl4 104 797 0 762 2 1 1 2 0 8 0
amappl3 96 106097 0 106029 5 2 3 3 0 8 0
amappl2 88 18963 0 18887 3 1 2 3 0 8 0
amappl1 80 72138 0 71599 23 10 13 23 0 8 0
amappl 88 170515 0 170267 11 3 8 8 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 72 133 0 3 3 0 3 3 0 8 0
uaddrrnd 24 18039 0 17747 2 0 2 2 0 8 0
uaddrbest 32 2 0 0 1 0 1 1 0 8 0
uaddr 24 18039 0 17747 2 0 2 2 0 8 0
vmmpekpl 168 127786 0 127697 5 0 5 5 0 8 0
vmmpepl 168 1043663 0 1041109 416 284 132 147 0 357 0
vmsppl 464 18038 0 17747 40 2 38 38 0 8 0
rwobjpl 56 269813 0 243989 374 9 365 365 0 8 0
pdppl 4096 36086 0 35762 900 562 338 338 0 8 14
pvpl 32 4917393 0 4897385 729 535 194 366 0 265 0
pmappl 248 18038 0 17747 20 1 19 19 0 8 0
extentpl 40 56 0 38 1 0 1 1 0 8 0
phpool 112 3024 0 1059 58 1 57 57 0 8 0
ddb{0}> machine ddbcpu 0
Invalid cpu 0
ddb{0}> trace
km_free(0,1000,ffffffff829d5d48,ffffffff829d5d60) at km_free+0x128 sys/uvm/uvm_km.c:866
pool_p_free(ffffffff82d84918,fffffd807e7b0f90) at pool_p_free+0x14b sys/kern/subr_pool.c:1012
pool_gc_pages(0) at pool_gc_pages+0x255 sys/kern/subr_pool.c:1583
taskq_thread(ffffffff82c01160) at taskq_thread+0xe5 sys/kern/kern_task.c:450
end trace frame: 0x0, count: -4
ddb{0}> machine ddbcpu 1
Stopped at x86_ipi_db+0x1e: addq $0x8,%rsp
x86_ipi_db(ffff800020d48ff0) at x86_ipi_db+0x1e sys/arch/amd64/amd64/db_interface.c:393
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27
acpicpu_idle() at acpicpu_idle+0x312 sys/dev/acpi/acpicpu.c:1206
sched_idle(ffff800020d48ff0) at sched_idle+0x41e sys/kern/kern_sched.c:191
end trace frame: 0x0, count: 10
ddb{1}> trace
x86_ipi_db(ffff800020d48ff0) at x86_ipi_db+0x1e sys/arch/amd64/amd64/db_interface.c:393
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27
acpicpu_idle() at acpicpu_idle+0x312 sys/dev/acpi/acpicpu.c:1206
sched_idle(ffff800020d48ff0) at sched_idle+0x41e sys/kern/kern_sched.c:191
end trace frame: 0x0, count: -5

---
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