uvm_fault: x86_ipi_db (4)

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syzbot

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Aug 7, 2021, 10:57:24 PM8/7/21
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Hello,

syzbot found the following issue on:

HEAD commit: 3395d9ad18ab Nuke a few Capt. Obvious comments.
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=16540a81300000
kernel config: https://syzkaller.appspot.com/x/.config?x=bf87b6915a88cd0d
dashboard link: https://syzkaller.appspot.com/bug?extid=9121b712c5668db4b64a

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9121b7...@syzkaller.appspotmail.com

*cpu1: uvm_fault(0xffffffff8287ed30, 0xffff800020cdf004, 0, 1) -> d
ddb{0}> trace
proc_trampoline() at proc_trampoline+0xdc
end of kernel
end trace frame: 0xc007a43ab0, count: -1
ddb{0}> show registers
rdi 0
rsi 0
rbp 0xffff800021263a70
rbx 0
rdx 0x8b
rcx 0x2
rax 0x2a
r8 0xffffffff820fdac4 kprintf+0x144
r9 0x1
r10 0x75402d0992e44e02
r11 0xd00100cf96220bf3
r12 0
r13 0
r14 0
r15 0
rip 0xffffffff812cc50c proc_trampoline+0xdc
cs 0x8
rflags 0x246
rsp 0xffff8000212639f0
ss 0
proc_trampoline+0xdc: movl $0,%gs:0x538
ddb{0}> show proc
PROC (syz-fuzzer) pid=181610 stat=onproc
flags process=2<EXEC> proc=4000000<THREAD>
pri=24, usrpri=50, nice=20
forw=0xffffffffffffffff, list=0xffff800021257a40,0xffff800021257270
process=0xffff80002120b250 user=0xffff80002125e000, vmspace=0xfffffd806f199008
estcpu=0, cpticks=1, pctcpu=0.0
user=0, sys=0, intr=0
ddb{0}> ps
PID TID PPID UID S FLAGS WAIT COMMAND
87991 126616 97052 0 7 0x2 syz-executor.1
59466 487348 97052 0 3 0x82 piperd syz-executor.0
97052 507577 38948 0 3 0x82 thrsleep syz-fuzzer
97052 492846 38948 0 3 0x4000082 nanoslp syz-fuzzer
97052 163059 38948 0 3 0x4000082 nanoslp syz-fuzzer
97052 393473 38948 0 3 0x4000082 thrsleep syz-fuzzer
97052 20834 38948 0 3 0x4000082 thrsleep syz-fuzzer
*97052 181610 38948 0 7 0x4000002 syz-fuzzer
97052 90659 38948 0 3 0x4000082 thrsleep syz-fuzzer
97052 400814 38948 0 3 0x4000082 thrsleep syz-fuzzer
38948 521345 74859 0 3 0x10008a sigsusp ksh
74859 333870 21912 0 3 0x9a select sshd
95101 143419 1 0 3 0x100083 ttyin getty
21912 123225 1 0 3 0x88 select sshd
68080 179262 44525 74 3 0x100092 bpf pflogd
44525 236425 1 0 3 0x80 netio pflogd
943 203251 24857 73 3 0x100010 biowait syslogd
24857 252452 1 0 3 0x100082 netio syslogd
43748 62879 1 0 3 0x100080 kqread resolvd
32939 300225 30555 77 3 0x100092 kqread dhcpleased
65529 220786 30555 77 3 0x100092 kqread dhcpleased
30555 371845 1 0 3 0x80 kqread dhcpleased
10055 100761 0 0 3 0x14200 bored smr
31413 86588 0 0 3 0x14200 pgzero zerothread
26938 443056 0 0 3 0x14200 aiodoned aiodoned
43657 484738 0 0 3 0x14200 syncer update
65286 150470 0 0 3 0x14200 cleaner cleaner
70431 509955 0 0 3 0x14200 reaper reaper
29348 341615 0 0 3 0x14200 pgdaemon pagedaemon
66207 64138 0 0 3 0x14200 bored crynlk
75528 239053 0 0 3 0x14200 bored crypto
28263 261671 0 0 3 0x14200 bored viomb
5378 364045 0 0 3 0x40014200 acpi0 acpi0
76693 363935 0 0 3 0x40014200 idle1
53918 453206 0 0 3 0x14200 bored softnet
88255 186518 0 0 3 0x14200 bored systqmp
85923 242117 0 0 3 0x14200 bored systq
6443 319521 0 0 3 0x40014200 bored softclock
46420 504678 0 0 3 0x40014200 idle0
1 457188 0 0 3 0x82 wait init
0 0 -1 0 3 0x10200 scheduler swapper
ddb{0}> show all locks
CPU 0:
exclusive mutex pvpl r = 0 (0xffffffff82845910)
#0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0 witness_lock+0x4b0 sys/kern/subr_witness.c:1182
#1 mtx_enter_try+0x100
#2 mtx_enter+0x4b sys/kern/kern_lock.c:266
#3 pool_put+0x8a sys/kern/subr_pool.c:799
#4 pmap_enter+0x7f6 sys/arch/amd64/amd64/pmap.c:2851
#5 uvm_fault_upper+0x2ae sys/uvm/uvm_fault.c:1033
#6 uvm_fault+0x164 sys/uvm/uvm_fault.c:609
#7 upageflttrap+0x82 sys/arch/amd64/amd64/trap.c:181
#8 usertrap+0x214 sys/arch/amd64/amd64/trap.c:403
#9 recall_trap+0x8
Process 87991 (syz-executor.1) thread 0xffff8000212562a0 (126616)
exclusive rrwlock inode r = 0 (0xfffffd80653f0b40)
#0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0 witness_lock+0x4b0 sys/kern/subr_witness.c:1182
#1 rw_enter+0x3e2 sys/kern/kern_rwlock.c:310
#2 rrw_enter+0x8b sys/kern/kern_rwlock.c:461
#3 VOP_LOCK+0x87 sys/kern/vfs_vops.c:614
#4 vn_lock+0x84 sys/kern/vfs_vnops.c:579
#5 vfs_lookup+0xdd sys/kern/vfs_lookup.c:413
#6 namei+0x55a sys/kern/vfs_lookup.c:245
#7 dounlinkat+0x99 sys/kern/vfs_syscalls.c:1854
#8 syscall+0x5a9 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#8 syscall+0x5a9 sys/arch/amd64/amd64/trap.c:587
#9 Xsyscall+0x128
exclusive kernel_lock &kernel_lock r = 1 (0xffffffff828cdd58)
#0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0 witness_lock+0x4b0 sys/kern/subr_witness.c:1182
#1 syscall+0x42d mi_syscall sys/sys/syscall_mi.h:93 [inline]
#1 syscall+0x42d sys/arch/amd64/amd64/trap.c:587
#2 Xsyscall+0x128
Process 97052 (syz-fuzzer) thread 0xffff8000212577a0 (181610)
exclusive rwlock amaplk r = 0 (0xfffffd8068901590)
#0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0 witness_lock+0x4b0 sys/kern/subr_witness.c:1182
#1 uvm_fault_check+0x3d2 sys/uvm/uvm_fault.c:774
#2 uvm_fault+0x102 sys/uvm/uvm_fault.c:601
#3 upageflttrap+0x82 sys/arch/amd64/amd64/trap.c:181
#4 usertrap+0x214 sys/arch/amd64/amd64/trap.c:403
#5 recall_trap+0x8
shared rwlock vmmaplk r = 0 (0xfffffd806f199020)
#0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0 witness_lock+0x4b0 sys/kern/subr_witness.c:1182
#1 uvmfault_lookup+0xd9 sys/uvm/uvm_fault.c:1701
#2 uvm_fault_check+0x3a sys/uvm/uvm_fault.c:674
#3 uvm_fault+0x102 sys/uvm/uvm_fault.c:601
#4 upageflttrap+0x82 sys/arch/amd64/amd64/trap.c:181
#5 usertrap+0x214 sys/arch/amd64/amd64/trap.c:403
#6 recall_trap+0x8
exclusive mutex pvpl r = 0 (0xffffffff82845910)
#0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0 witness_lock+0x4b0 sys/kern/subr_witness.c:1182
#1 mtx_enter_try+0x100
#2 mtx_enter+0x4b sys/kern/kern_lock.c:266
#3 pool_put+0x8a sys/kern/subr_pool.c:799
#4 pmap_enter+0x7f6 sys/arch/amd64/amd64/pmap.c:2851
#5 uvm_fault_upper+0x2ae sys/uvm/uvm_fault.c:1033
#6 uvm_fault+0x164 sys/uvm/uvm_fault.c:609
#7 upageflttrap+0x82 sys/arch/amd64/amd64/trap.c:181
#8 usertrap+0x214 sys/arch/amd64/amd64/trap.c:403
#9 recall_trap+0x8
Process 943 (syslogd) thread 0xffff800021193268 (203251)
exclusive rrwlock inode r = 0 (0xfffffd806e61f2c0)
#0 witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0 witness_lock+0x4b0 sys/kern/subr_witness.c:1182
#1 rw_enter+0x3e2 sys/kern/kern_rwlock.c:310
#2 rrw_enter+0x8b sys/kern/kern_rwlock.c:461
#3 VOP_LOCK+0x87 sys/kern/vfs_vops.c:614
#4 vn_lock+0x84 sys/kern/vfs_vnops.c:579
#5 sys_fsync+0x113 sys/kern/vfs_syscalls.c:2893
#6 syscall+0x5a9 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#6 syscall+0x5a9 sys/arch/amd64/amd64/trap.c:587
#7 Xsyscall+0x128
ddb{0}> show malloc
Type InUse MemUse HighUse Limit Requests Type Lim
devbuf 10123 6429K 6558K 78643K 11651 0
pcb 13 8K 8K 78643K 21 0
rtable 106 3K 3K 78643K 232 0
ifaddr 44 10K 10K 78643K 60 0
counters 44 34K 34K 78643K 48 0
ioctlops 0 0K 4K 78643K 1489 0
iov 0 0K 0K 78643K 8 0
mount 1 1K 1K 78643K 1 0
log 0 0K 0K 78643K 6 0
vnodes 1218 77K 77K 78643K 1266 0
UFS quota 1 32K 32K 78643K 1 0
UFS mount 5 36K 36K 78643K 5 0
shm 2 1K 5K 78643K 10 0
VM map 2 1K 1K 78643K 2 0
sem 12 1K 1K 78643K 64 0
dirhash 12 2K 2K 78643K 12 0
ACPI 1697 195K 286K 78643K 12598 0
file desc 4 9K 25K 78643K 22996 0
proc 69 87K 111K 78643K 407 0
subproc 32 2K 2K 78643K 68 0
NFS srvsock 1 0K 0K 78643K 1 0
NFS daemon 1 16K 16K 78643K 1 0
in_multi 33 2K 2K 78643K 55 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 2K 78643K 452 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 341 40K 41K 78643K 273076 0
UVM aobj 7 2K 2K 78643K 7 0
memdesc 1 4K 4K 78643K 1 0
crypto data 1 1K 1K 78643K 1 0
NDP 8 0K 0K 78643K 16 0
temp 71 4197K 4261K 78643K 48532 0
kqueue 10 14K 14K 78643K 10 0
SYN cache 2 16K 16K 78643K 2 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 29 0 26 1 0 1 1 0 8 0
rtentry 112 67 0 23 2 0 2 2 0 8 0
unpcb 120 12449 0 12434 1 0 1 1 0 8 0
syncache 296 4 0 4 1 1 0 1 0 8 0
tcpqe 32 749 0 749 3 3 0 2 0 8 0
tcpcb 736 19 0 15 1 0 1 1 0 8 0
arp 120 10 0 4 1 0 1 1 0 8 0
inpcb 304 69 0 62 1 0 1 1 0 8 0
nd6 48 12 0 6 1 0 1 1 0 8 0
kcovpl 48 4 0 2 1 0 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 15 0 11 1 0 1 1 0 8 0
pfstkey 112 15 0 11 1 0 1 1 0 8 0
pfstate 320 15 0 11 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 256 276 0 88 12 0 12 12 0 8 0
art_table 32 277 0 88 2 0 2 2 0 8 0
art_node 16 66 0 26 1 0 1 1 0 8 0
semupl 112 1 0 1 1 1 0 1 0 8 0
semapl 112 62 0 52 1 0 1 1 0 8 0
shmpl 112 4 0 0 1 0 1 1 0 8 0
dirhash 1024 17 0 0 3 0 3 3 0 8 0
dino2pl 256 28256 0 26840 89 0 89 89 0 8 0
ffsino 272 28256 0 26840 95 0 95 95 0 8 0
nchpl 144 55893 0 54284 61 0 61 61 0 8 0
uvmvnodes 72 5926 0 0 108 0 108 108 0 8 0
vnodes 224 5926 0 0 349 0 349 349 0 8 0
namei 1024 119328 0 119327 2 1 1 1 0 8 0
percpumem 16 36 0 2 1 0 1 1 0 8 0
scxspl 216 154565 0 154564 10 9 1 8 0 8 0
plimitpl 152 19 0 10 1 0 1 1 0 8 0
sigapl 424 23240 0 23207 6 2 4 5 0 8 0
futexpl 56 104923 0 104923 1 0 1 1 0 8 1
knotepl 112 58 0 0 2 0 2 2 0 8 0
kqueuepl 216 33915 0 33909 8 7 1 2 0 8 0
pipepl 336 102 0 92 4 2 2 2 0 8 1
fdescpl 496 23224 0 23207 3 0 3 3 0 8 0
filepl 152 84792 0 84680 15 10 5 6 0 8 0
lockfpl 104 49 0 47 1 0 1 1 0 8 0
lockfspl 48 22 0 20 1 0 1 1 0 8 0
sessionpl 144 20 0 9 1 0 1 1 0 8 0
pgrppl 48 20 0 9 1 0 1 1 0 8 0
ucredpl 96 1886 0 1873 1 0 1 1 0 8 0
zombiepl 144 23207 0 23207 2 1 1 1 0 8 1
processpl 1072 23240 0 23207 3 0 3 3 0 8 0
procpl 672 46762 0 46722 9 5 4 5 0 8 0
sockpl 480 12547 0 12522 13 9 4 5 0 8 0
mcl64k 65536 3 0 0 1 0 1 1 0 8 0
mcl16k 16384 1 0 0 1 0 1 1 0 8 0
mcl12k 12288 2 0 0 1 0 1 1 0 8 0
mcl8k 8192 6 0 0 1 0 1 1 0 8 0
mcl4k 4096 21 0 0 3 0 3 3 0 8 0
mcl2k2 2112 9 0 0 1 0 1 1 0 8 0
mcl2k 2048 338 0 0 34 5 29 34 0 8 0
mtagpl 96 3 0 0 1 0 1 1 0 8 0
mbufpl 256 733 0 0 21 0 21 21 0 8 0
bufpl 280 26484 0 20148 453 0 453 453 0 8 0
anonpl 24 5697011 0 5665963 254 13 241 241 0 186 2
amapchunkpl 152 636271 0 634913 69 11 58 58 0 158 2
amappl16 200 33376 0 32253 62 2 60 60 0 8 0
amappl15 192 11253 0 11252 1 0 1 1 0 8 0
amappl14 184 4 0 3 2 1 1 1 0 8 0
amappl13 176 42 0 41 1 0 1 1 0 8 0
amappl12 168 20 0 14 1 0 1 1 0 8 0
amappl11 160 56 0 41 1 0 1 1 0 8 0
amappl10 152 47 0 38 1 0 1 1 0 8 0
amappl9 144 11700 0 11697 1 0 1 1 0 8 0
amappl8 136 658 0 612 2 0 2 2 0 8 0
amappl7 128 315 0 301 1 0 1 1 0 8 0
amappl6 120 11605 0 11593 1 0 1 1 0 8 0
amappl5 112 23118 0 23098 1 0 1 1 0 8 0
amappl4 104 615 0 590 1 0 1 1 0 8 0
amappl3 96 54 0 50 1 0 1 1 0 8 0
amappl2 88 511 0 457 2 0 2 2 0 8 0
amappl1 80 384725 0 384298 14 4 10 13 0 8 0
amappl 88 268835 0 268566 8 1 7 7 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 64 6 0 0 1 0 1 1 0 8 0
uaddrrnd 24 23224 0 23207 1 0 1 1 0 8 0
uaddrbest 32 2 0 0 1 0 1 1 0 8 0
uaddr 24 23224 0 23207 1 0 1 1 0 8 0
vmmpekpl 168 99761 0 99738 2 0 2 2 0 8 0
vmmpepl 168 2565833 0 2563349 279 108 171 171 0 357 52
vmsppl 368 23223 0 23207 2 0 2 2 0 8 0
rwobjpl 56 420004 0 418003 36 6 30 30 0 8 1
pdppl 4096 46456 0 46414 74 28 46 50 0 8 4
pvpl 32 11315552 0 11281411 392 39 353 353 0 265 4
pmappl 224 23223 0 23207 2 0 2 2 0 8 0
extentpl 40 58 0 40 1 0 1 1 0 8 0
phpool 112 349 0 39 10 0 10 10 0 8 0
ddb{0}> machine ddbcpu 0
Invalid cpu 0
ddb{0}> trace
proc_trampoline() at proc_trampoline+0xdc
end of kernel
end trace frame: 0xc007a43ab0, count: -1
ddb{0}> machine ddbcpu 1
Stopped at x86_ipi_db+0x1a: addq $0x8,%rsp
x86_ipi_db(ffff800020d38ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:353
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23
x86_bus_space_io_write_1(3f8,0,30) at x86_bus_space_io_write_1+0x31 sys/arch/amd64/amd64/bus_space.c:759
comcnputc(800,30) at comcnputc+0x128 bus_space_barrier machine/bus.h:481 [inline]
comcnputc(800,30) at comcnputc+0x128 sys/dev/ic/com.c:1263
cnputc(30) at cnputc+0x4b sys/dev/cons.c:239
db_putchar(30) at db_putchar+0x3fc sys/ddb/db_output.c:155
kprintf() at kprintf+0x1f19 sys/kern/subr_prf.c:1068
db_printf(ffffffff824f54a2) at db_printf+0x85 sys/kern/subr_prf.c:502
fault(ffffffff824a9a3b) at fault+0x95 sys/arch/amd64/amd64/trap.c:154
kpageflttrap(ffff80002229aeb0,ffff800020cdf004) at kpageflttrap+0x246 sys/arch/amd64/amd64/trap.c:275
kerntrap(ffff80002229aeb0) at kerntrap+0xef sys/arch/amd64/amd64/trap.c:318
alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b
ufs_lookup() at ufs_lookup+0x4ea sys/ufs/ufs/ufs_lookup.c:281
end trace frame: 0xffff80002229b0f0, count: 0
ddb{1}> trace
x86_ipi_db(ffff800020d38ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:353
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23
x86_bus_space_io_write_1(3f8,0,30) at x86_bus_space_io_write_1+0x31 sys/arch/amd64/amd64/bus_space.c:759
comcnputc(800,30) at comcnputc+0x128 bus_space_barrier machine/bus.h:481 [inline]
comcnputc(800,30) at comcnputc+0x128 sys/dev/ic/com.c:1263
cnputc(30) at cnputc+0x4b sys/dev/cons.c:239
db_putchar(30) at db_putchar+0x3fc sys/ddb/db_output.c:155
kprintf() at kprintf+0x1f19 sys/kern/subr_prf.c:1068
db_printf(ffffffff824f54a2) at db_printf+0x85 sys/kern/subr_prf.c:502
fault(ffffffff824a9a3b) at fault+0x95 sys/arch/amd64/amd64/trap.c:154
kpageflttrap(ffff80002229aeb0,ffff800020cdf004) at kpageflttrap+0x246 sys/arch/amd64/amd64/trap.c:275
kerntrap(ffff80002229aeb0) at kerntrap+0xef sys/arch/amd64/amd64/trap.c:318
alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b
ufs_lookup() at ufs_lookup+0x4ea sys/ufs/ufs/ufs_lookup.c:281
VOP_LOOKUP(fffffd80784742b8,ffff80002229b2b0,ffff80002229b2e8) at VOP_LOOKUP+0x5b sys/kern/vfs_vops.c:88
vfs_lookup(ffff80002229b280) at vfs_lookup+0x737 sys/kern/vfs_lookup.c:561
namei(ffff80002229b280) at namei+0x55a sys/kern/vfs_lookup.c:245
dounlinkat(ffff8000212562a0,ffffff9c,7f7ffffd0cd0,8) at dounlinkat+0x99 sys/kern/vfs_syscalls.c:1854
syscall(ffff80002229b460) at syscall+0x5a9 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff80002229b460) at syscall+0x5a9 sys/arch/amd64/amd64/trap.c:587
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7f7ffffd0cc0, count: -20


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Anton Lindqvist

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Aug 8, 2021, 1:33:23 AM8/8/21
to syzbot, syzkaller-o...@googlegroups.com
Grabled panicstr...

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