uvm_fault: pckbc_start

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 9c4fc15973cf Drop netmpls/mpls.h include, not needed here.
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=112a1c6cc00000
kernel config: https://syzkaller.appspot.com/x/.config?x=fa145722143cbd64
dashboard link: https://syzkaller.appspot.com/bug?extid=c9cea3810ba7c60bad69
compiler:

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+c9cea3...@syzkaller.appspotmail.com

uvm_fault(0xfffffd807f00d870, 0x1c, 0, 1) -> e
kernel: page fault trap, code=0
Stopped at pckbc_start+0x16e: movsxdq 0x1c(%r14),%rax
ddb{1}>
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
kernel page fault
uvm_fault(0xfffffd807f00d870, 0x1c, 0, 1) -> e
pckbc_start(ffff800000026e00,0) at pckbc_start+0x16e sys/dev/ic/pckbc.c:809
end trace frame: 0xffff800020c24930, count: 0
ddb{1}> trace
pckbc_start(ffff800000026e00,0) at pckbc_start+0x16e sys/dev/ic/pckbc.c:809
pckbc_enqueue_cmd(ffff800000026e00,0,ffff800020c24957,1,0,1) at
pckbc_enqueue_cmd+0x24a sys/dev/ic/pckbc.c:918
pckbd_enable(ffff80000066a380,0) at pckbd_enable+0x125
sys/dev/pckbc/pckbd.c:481
wskbd_mux_close(ffff80000001ce00) at wskbd_mux_close+0x98
sys/dev/wscons/wskbd.c:891
wsmuxclose(4501,1,2000,ffff800020b42270) at wsmuxclose+0xb5 wsmux_do_close
sys/dev/wscons/wsmux.c:313 [inline]
wsmuxclose(4501,1,2000,ffff800020b42270) at wsmuxclose+0xb5
sys/dev/wscons/wsmux.c:277
spec_close(ffff800020c24aa0) at spec_close+0x3a0 sys/kern/spec_vnops.c:553
VOP_CLOSE(fffffd807e192498,1,fffffd807f7c7a80,ffff800020b42270) at
VOP_CLOSE+0x70 sys/kern/vfs_vops.c:174
vn_closefile(fffffd806ea6ed18,ffff800020b42270) at vn_closefile+0x160
vn_close sys/kern/vfs_vnops.c:289 [inline]
vn_closefile(fffffd806ea6ed18,ffff800020b42270) at vn_closefile+0x160
sys/kern/vfs_vnops.c:575
fdrop(fffffd806ea6ed18,ffff800020b42270) at fdrop+0xe1
sys/kern/kern_descrip.c:1260
closef(fffffd806ea6ed18,ffff800020b42270) at closef+0x129
sys/kern/kern_descrip.c:1244
doopenat(ffff800020b42270,ffffff9c,20000000,510,0,ffff800020c24ed0) at
doopenat+0x846 sys/kern/vfs_syscalls.c:1117
syscall(ffff800020c24f80) at syscall+0x5ac mi_syscall
sys/sys/syscall_mi.h:99 [inline]
syscall(ffff800020c24f80) at syscall+0x5ac sys/arch/amd64/amd64/trap.c:574
Xsyscall(6,0,ffffffffffffffb0,0,4,243c0da8010) at Xsyscall+0x128
end of kernel
end trace frame: 0x245f8303f80, count: -13
ddb{1}> show registers
rdi 0
rsi 0
rbp 0xffff800020c24890
rbx 0
rdx 0x40000 acpi_pdirpa+0x2be68
rcx 0xffff800000941e00
rax 0xffffffff81269c64 pckbc_start+0x44
r8 0
r9 0x1
r10 0x5fac2c5d77192d70
r11 0xefc0d4650d66ce75
r12 0xffff800000026e00
r13 0xffff80000066c000
r14 0
r15 0
rip 0xffffffff81269d8e pckbc_start+0x16e
cs 0x8
rflags 0x10246 __ALIGN_SIZE+0xf246
rsp 0xffff800020c24830
ss 0x10
pckbc_start+0x16e: movsxdq 0x1c(%r14),%rax
ddb{1}> show proc
PROC (syz-executor.0) pid=269490 stat=onproc
flags process=0 proc=4000000<THREAD>
pri=86, usrpri=86, nice=20
forw=0xffffffffffffffff, list=0xffff800020b424c8,0xffff800020b42988
process=0xffff800020b449e8 user=0xffff800020c20000,
vmspace=0xfffffd807f00d870
estcpu=36, cpticks=102, pctcpu=1.1
user=0, sys=102, intr=0
ddb{1}> ps
PID TID PPID UID S FLAGS WAIT COMMAND
40911 288281 77938 0 7 0 syz-executor.0
*40911 269490 77938 0 7 0x4000000 syz-executor.0
40911 340378 77938 0 3 0x4000080 fsleep syz-executor.0
19185 472661 1 0 3 0x100083 ttyin getty
13682 164219 0 0 3 0x14200 bored sosplice
13039 281533 83428 0 3 0x82 nanosleep syz-executor.1
77938 247960 83428 0 3 0x82 nanosleep syz-executor.0
83428 282306 88246 0 3 0x82 thrsleep syz-fuzzer
83428 185125 88246 0 3 0x4000082 nanosleep syz-fuzzer
83428 407333 88246 0 3 0x4000082 thrsleep syz-fuzzer
83428 309333 88246 0 3 0x4000082 kqread syz-fuzzer
83428 146002 88246 0 3 0x4000082 thrsleep syz-fuzzer
83428 118453 88246 0 3 0x4000082 thrsleep syz-fuzzer
83428 287648 88246 0 3 0x4000082 thrsleep syz-fuzzer
83428 12729 88246 0 3 0x4000082 thrsleep syz-fuzzer
83428 387863 88246 0 3 0x4000082 thrsleep syz-fuzzer
83428 264612 88246 0 3 0x4000082 thrsleep syz-fuzzer
88246 328502 65948 0 3 0x10008a pause ksh
65948 75498 74932 0 3 0x92 select sshd
74932 336194 1 0 3 0x80 select sshd
34838 363075 42920 73 3 0x100010 biowait syslogd
42920 448090 1 0 3 0x100082 netio syslogd
20918 346299 1 77 3 0x100090 poll dhclient
27906 24302 1 0 3 0x80 poll dhclient
9544 28589 0 0 3 0x14200 pgzero zerothread
27897 386120 0 0 3 0x14200 aiodoned aiodoned
31545 144853 0 0 3 0x14200 syncer update
80774 17299 0 0 3 0x14200 cleaner cleaner
84065 104207 0 0 3 0x14200 reaper reaper
28410 407096 0 0 3 0x14200 pgdaemon pagedaemon
87114 304357 0 0 3 0x14200 bored crynlk
58391 72757 0 0 3 0x14200 bored crypto
20987 291356 0 0 3 0x40014200 acpi0 acpi0
95438 492443 0 0 3 0x40014200 idle1
98954 61411 0 0 3 0x14200 bored softnet
38922 285156 0 0 3 0x14200 bored systqmp
480 149569 0 0 3 0x14200 bored systq
45041 523491 0 0 3 0x40014200 bored softclock
94693 484999 0 0 3 0x40014200 idle0
1 375398 0 0 3 0x82 wait init
0 0 -1 0 3 0x10200 scheduler swapper
ddb{1}> show all locks
Process 40911 (syz-executor.0) thread 0xffff800020b42270 (269490)
exclusive rwlock fdlock r = 0 (0xfffffd806f1c0bd0) locked @
/syzkaller/managers/multicore/kernel/sys/kern/vfs_syscalls.c:1104
#0 witness_lock+0x58a sys/kern/subr_witness.c:1205
#1 doopenat+0x828
#2 syscall+0x5ac mi_syscall sys/sys/syscall_mi.h:99 [inline]
#2 syscall+0x5ac sys/arch/amd64/amd64/trap.c:574
#3 Xsyscall+0x128
exclusive kernel_lock &kernel_lock r = 2 (0xffffffff82335598) locked @
/syzkaller/managers/multicore/kernel/sys/arch/amd64/amd64/trap.c:161
#0 witness_lock+0x58a sys/kern/subr_witness.c:1205
#1 syscall+0x47f mi_syscall sys/sys/syscall_mi.h:91 [inline]
#1 syscall+0x47f sys/arch/amd64/amd64/trap.c:574
#2 Xsyscall+0x128
Process 34838 (syslogd) thread 0xffff800020b95c30 (363075)
exclusive rrwlock inode r = 0 (0xfffffd806ebc34d8) locked @
/syzkaller/managers/multicore/kernel/sys/ufs/ufs/ufs_vnops.c:1547
#0 witness_lock+0x58a sys/kern/subr_witness.c:1205
#1 _rw_enter+0x44d sys/kern/kern_rwlock.c:280
#2 _rrw_enter+0x60 sys/kern/kern_rwlock.c:410
#3 VOP_LOCK+0x57 sys/kern/vfs_vops.c:602
#4 vn_lock+0x6e sys/kern/vfs_vnops.c:549
#5 sys_fsync+0x114 sys/kern/vfs_syscalls.c:2704
#6 syscall+0x5ac mi_syscall sys/sys/syscall_mi.h:99 [inline]
#6 syscall+0x5ac sys/arch/amd64/amd64/trap.c:574
#7 Xsyscall+0x128
ddb{1}> show malloc
Type InUse MemUse HighUse Limit Requests Type Lim Kern Lim
devbuf 9498 6349K 6357K 78643K 10781 0 0
pcb 23 9K 11K 78643K 358 0 0
rtable 100 3K 4K 78643K 250 0 0
ifaddr 48 11K 12K 78643K 91 0 0
counters 39 33K 33K 78643K 39 0 0
ioctlops 0 0K 2K 78643K 17 0 0
iov 0 0K 28K 78643K 65 0 0
mount 1 1K 1K 78643K 1 0 0
vnodes 1205 75K 76K 78643K 1540 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 13 0 0
VM map 2 1K 1K 78643K 2 0 0
sem 12 0K 0K 78643K 83 0 0
dirhash 12 2K 2K 78643K 12 0 0
ACPI 1792 194K 288K 78643K 12592 0 0
file desc 5 13K 21K 78643K 526 0 0
sigio 0 0K 0K 78643K 4 0 0
proc 41 38K 58K 78643K 322 0 0
subproc 64 65538K 67586K 78643K 70 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 69 0 0
in_multi 33 2K 2K 78643K 53 0 0
ether_multi 1 0K 0K 78643K 6 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 225 0 0
pfkey data 0 0K 4K 78643K 2 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 84 20K 29K 78643K 2463 0 0
UVM aobj 37 2K 2K 78643K 40 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 14 0 0
NDP 9 0K 0K 78643K 25 0 0
temp 134 2363K 2427K 78643K 4223 0 0
kqueue 0 0K 0K 78643K 7 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 4 0 0 1 0 1 1 0
8 0
inpcbpl 280 255 0 247 1 0 1 1 0
8 0
plimitpl 152 17 0 10 1 0 1 1 0
8 0
plcache 128 20 0 0 1 0 1 1 0
8 0
rtentry 112 41 0 1 2 0 2 2 0
8 0
syncache 264 4 0 4 1 1 0 1 0
8 0
tcpqe 32 1 0 1 1 1 0 1 0
8 0
tcpcb 544 92 0 87 1 0 1 1 0
8 0
nd6 48 4 0 0 1 0 1 1 0
8 0
ppxss 1128 7 0 7 4 3 1 1 0
8 1
art_heap8 4096 1 0 0 1 0 1 1 0
8 0
art_heap4 256 186 0 0 12 0 12 12 0
8 0
art_table 32 187 0 0 2 0 2 2 0
8 0
art_node 16 40 0 6 1 0 1 1 0
8 0
sysvmsgpl 40 10 0 4 1 0 1 1 0
8 0
semupl 112 1 0 1 1 1 0 1 0
8 0
semapl 112 79 0 69 1 0 1 1 0
8 0
shmpl 112 38 0 3 2 0 2 2 0
8 1
dirhash 1024 17 0 0 3 0 3 3 0
8 0
dino1pl 128 2428 0 1016 46 0 46 46 0
8 0
ffsino 272 2428 0 1016 95 0 95 95 0
8 0
nchpl 144 3376 0 1753 61 0 61 61 0
8 0
uvmvnodes 72 2533 0 0 47 0 47 47 0
8 0
vnodes 200 2533 0 0 134 0 134 134 0
8 0
namei 1024 9339 0 9339 2 1 1 1 0
8 1
percpumem 16 30 0 0 1 0 1 1 0
8 0
scsiplug 64 3 0 3 2 2 0 1 0
8 0
scxspl 192 9744 0 9743 11 10 1 6 0
8 0
sigapl 432 695 0 682 2 0 2 2 0
8 0
futexpl 56 6221 0 6220 1 0 1 1 0
8 0
knotepl 112 204 0 177 3 2 1 2 0
8 0
kqueuepl 104 179 0 177 1 0 1 1 0
8 0
pipepl 112 492 0 473 4 3 1 2 0
8 0
fdescpl 488 696 0 682 3 1 2 3 0
8 0
filepl 152 4270 0 4174 8 3 5 7 0
8 1
lockfpl 104 175 0 175 2 1 1 1 0
8 1
lockfspl 32 203 0 203 2 1 1 1 0
8 1
sessionpl 112 18 0 8 1 0 1 1 0
8 0
pgrppl 48 29 0 19 1 0 1 1 0
8 0
ucredpl 96 935 0 928 1 0 1 1 0
8 0
zombiepl 144 682 0 681 2 1 1 1 0
8 0
processpl 840 711 0 681 4 0 4 4 0
8 0
procpl 600 1871 0 1830 4 0 4 4 0
8 0
sosppl 128 14 0 14 3 2 1 1 0
8 1
sockpl 384 566 0 548 4 1 3 4 0
8 1
mcl64k 65536 229 0 0 29 6 23 29 0
8 1
mcl16k 16384 4 0 0 1 0 1 1 0
8 0
mcl12k 12288 4 0 0 1 0 1 1 0
8 0
mcl9k 9216 4 0 0 1 0 1 1 0
8 0
mcl8k 8192 3 0 0 1 0 1 1 0
8 0
mcl4k 4096 6 0 0 1 0 1 1 0
8 0
mcl2k2 2112 3 0 0 1 0 1 1 0
8 0
mcl2k 2048 106 0 0 13 0 13 13 0
8 0
mtagpl 80 1 0 0 1 0 1 1 0
8 0
mbufpl 256 311 0 0 19 0 19 19 0
8 0
bufpl 256 6174 0 1021 323 0 323 323 0
8 0
anonpl 16 77689 0 69629 61 21 40 48 0
125 5
amapchunkpl 152 3828 0 3737 10 1 9 9 0
158 4
amappl16 192 3408 0 2983 45 22 23 33 0
8 0
amappl15 184 5 0 4 2 1 1 1 0
8 0
amappl14 176 7 0 6 2 1 1 1 0
8 0
amappl13 168 27 0 23 1 0 1 1 0
8 0
amappl12 160 278 0 275 2 1 1 1 0
8 0
amappl11 152 424 0 414 1 0 1 1 0
8 0
amappl10 144 59 0 57 2 1 1 1 0
8 0
amappl9 136 592 0 589 1 0 1 1 0
8 0
amappl8 128 411 0 386 1 0 1 1 0
8 0
amappl7 120 36 0 31 1 0 1 1 0
8 0
amappl6 112 56 0 47 1 0 1 1 0
8 0
amappl5 104 131 0 119 1 0 1 1 0
8 0
amappl4 96 279 0 258 2 1 1 2 0
8 0
amappl3 88 148 0 142 1 0 1 1 0
8 0
amappl2 80 5705 0 5654 2 0 2 2 0
8 0
amappl1 72 22959 0 22539 24 14 10 19 0
8 0
amappl 72 2080 0 2045 1 0 1 1 0
75 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
dma64 64 259 0 259 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 39 0 3 1 0 1 1 0
8 0
uaddrrnd 24 696 0 682 1 0 1 1 0
8 0
uaddrbest 32 2 0 0 1 0 1 1 0
8 0
uaddr 24 696 0 682 1 0 1 1 0
8 0
vmmpekpl 168 9887 0 9863 2 0 2 2 0
8 0
vmmpepl 168 81115 0 79746 96 30 66 72 0
357 0
vmsppl 360 695 0 682 2 0 2 2 0
8 0
pdppl 4096 1399 0 1364 5 0 5 5 0
8 0
pvpl 32 251363 0 239817 139 30 109 128 0 265
14
pmappl 224 695 0 682 1 0 1 1 0
8 0
extentpl 40 39 0 25 1 0 1 1 0
8 0
phpool 112 508 0 9 15 0 15 15 0
8 0


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[Anton Lindqvist]

This one is hopefully also fixed by now.

#syz fix: Serialize access to the list of attached child devices belonging to a wsmux. When invoking wsevsrc_* functions on a attached child device, underlying driver can sleep; this introduces a race where another thread is able to modify the list leading to all kinds of corruptions.