syzbot
uvm_fault: device_lookup
Status:
upstream: reported on 2026/07/25 03:44
Reported-by: syzbot+2cbc1aa46b0f2ece7b02@syzkaller.appspotmail.com
First crash: 77d, last: 29d
Sample crash report:
uvm_fault(0xfffff1800b1f73d0, 0xee40, 0, 1) -> e
kernel: page fault trap, code=0
Stopped at device_lookup+0x7b: movl 0x40(%rax),%r15d
TID PID UID PRFLAGS PFLAGS CPU COMMAND
* 4732 1301 0 0x2 0 0K syz-executor
device_lookup(ffffffff83902ad0,0) at device_lookup+0x7b sys/kern/subr_autoconf.c:954
disk_lookup(ffffffff83902ad0,0) at disk_lookup+0x3b sys/kern/subr_disk.c:-1
sdstrategy(fffff1806d145bb8) at sdstrategy+0x53 sys/scsi/sd.c:530
spec_strategy(ffff80002a35e818) at spec_strategy+0x42 sys/kern/spec_vnops.c:448
VOP_STRATEGY(fffff1800b209510,fffff1806d145bb8) at VOP_STRATEGY+0x65 sys/kern/vfs_vops.c:636
ufs_strategy(ffff80002a35e8b8) at ufs_strategy+0x1f0 sys/ufs/ufs/ufs_vnops.c:-1
VOP_STRATEGY(fffff1806d8b0a60,fffff1806d145bb8) at VOP_STRATEGY+0x65 sys/kern/vfs_vops.c:636
bwrite(fffff1806d145bb8) at bwrite+0x30a sys/kern/vfs_bio.c:616
ufs_dirremove(fffff1806d8b0a60,fffff1806c0dde18,800c,1) at ufs_dirremove+0x290 sys/ufs/ufs/ufs_lookup.c:919
ufs_rmdir(ffff80002a35ea20) at ufs_rmdir+0x238 sys/ufs/ufs/ufs_vnops.c:1248
VOP_RMDIR(fffff1806d8b0a60,fffff1807b080398,ffff80002a35eaf8) at VOP_RMDIR+0x192 sys/kern/vfs_vops.c:413
dounlinkat(ffff800045fef240,ffffff9c,7395cf129560,8) at dounlinkat+0x2e0 sys/kern/vfs_syscalls.c:1840
syscall(ffff80002a35ec70) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a35ec70) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:791
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7395cf129550, count: 1
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(0xfffff1800b1f73d0, 0xee40, 0, 1) -> e
ddb{0}> show kasan
No such command
ddb{0}> trace
device_lookup(ffffffff83902ad0,0) at device_lookup+0x7b sys/kern/subr_autoconf.c:954
disk_lookup(ffffffff83902ad0,0) at disk_lookup+0x3b sys/kern/subr_disk.c:-1
sdstrategy(fffff1806d145bb8) at sdstrategy+0x53 sys/scsi/sd.c:530
spec_strategy(ffff80002a35e818) at spec_strategy+0x42 sys/kern/spec_vnops.c:448
VOP_STRATEGY(fffff1800b209510,fffff1806d145bb8) at VOP_STRATEGY+0x65 sys/kern/vfs_vops.c:636
ufs_strategy(ffff80002a35e8b8) at ufs_strategy+0x1f0 sys/ufs/ufs/ufs_vnops.c:-1
VOP_STRATEGY(fffff1806d8b0a60,fffff1806d145bb8) at VOP_STRATEGY+0x65 sys/kern/vfs_vops.c:636
bwrite(fffff1806d145bb8) at bwrite+0x30a sys/kern/vfs_bio.c:616
ufs_dirremove(fffff1806d8b0a60,fffff1806c0dde18,800c,1) at ufs_dirremove+0x290 sys/ufs/ufs/ufs_lookup.c:919
ufs_rmdir(ffff80002a35ea20) at ufs_rmdir+0x238 sys/ufs/ufs/ufs_vnops.c:1248
VOP_RMDIR(fffff1806d8b0a60,fffff1807b080398,ffff80002a35eaf8) at VOP_RMDIR+0x192 sys/kern/vfs_vops.c:413
dounlinkat(ffff800045fef240,ffffff9c,7395cf129560,8) at dounlinkat+0x2e0 sys/kern/vfs_syscalls.c:1840
syscall(ffff80002a35ec70) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a35ec70) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:791
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7395cf129550, count: -14
ddb{0}> show registers
rdi 0x2
rsi 0
rbp 0xffff80002a35e750
rbx 0xfffff1806d28da80
rdx 0
rcx 0
rax 0xee00 __ALIGN_SIZE+0xde00
r8 0xffffffffffffffff
r9 0x1
r10 0x2c3da5091bba3ce6
r11 0x57944786d186973b
r12 0x2
r13 0
r14 0xee00 __ALIGN_SIZE+0xde00
r15 0xffffffff83902ad0 sd_cd
rip 0xffffffff817d5d6b device_lookup+0x7b
cs 0x8
rflags 0x10206 __ALIGN_SIZE+0xf206
rsp 0xffff80002a35e720
ss 0x10
device_lookup+0x7b: movl 0x40(%rax),%r15d
ddb{0}> show proc
PROC (syz-executor) tid=4732 pid=1301 tcnt=1 stat=onproc
flags process=2<EXEC> proc=0
runpri=32, usrpri=86, slppri=32, nice=20
wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
forw=0xffffffffffffffff, list=0xffff800045fef770,0xffff800038f9c560
process=0xffff800045ff5348 user=0xffff80002a359000, vmspace=0xfffff1800b1f73d0
estcpu=36, cpticks=16, pctcpu=0.2, user=0, sys=16, intr=0
ddb{0}> ps
PID TID PPID UID S PRLAGS PFLAGS WAIT COMMAND
43416 171294 37252 0 2 0x100000 0 sh
37252 322831 72777 0 3 0x100002 0x88 sigsusp sh
98597 44665 66394 0 2 0 0 syz-executor
98597 262084 66394 0 3 0 0x4000080 pipewr syz-executor
98597 300464 66394 0 3 0 0x4000080 pipewr syz-executor
54830 333912 0 0 3 0x14000 0x280 nfsidl nfsio
21576 471465 0 0 3 0x14000 0x280 nfsidl nfsio
32565 484840 0 0 3 0x14000 0x280 nfsidl nfsio
88522 336188 0 0 3 0x14000 0x280 nfsidl nfsio
52306 416608 0 0 3 0x14000 0x280 nfsidl nfsio
84804 396155 0 0 3 0x14000 0x280 nfsidl nfsio
8359 469576 0 0 3 0x14000 0x280 nfsidl nfsio
4669 345509 0 0 3 0x14000 0x280 nfsidl nfsio
12541 349458 0 0 3 0x14000 0x280 nfsidl nfsio
50295 327677 0 0 3 0x14000 0x280 nfsidl nfsio
21812 136187 0 0 3 0x14000 0x280 nfsidl nfsio
76358 520673 0 0 3 0x14000 0x280 nfsidl nfsio
59538 331505 0 0 3 0x14000 0x280 nfsidl nfsio
89930 174177 0 0 3 0x14000 0x280 nfsidl nfsio
52663 76528 0 0 3 0x14000 0x280 nfsidl nfsio
12555 102897 0 0 3 0x14000 0x280 nfsidl nfsio
71880 172466 0 0 3 0x14000 0x280 nfsidl nfsio
96619 200039 0 0 3 0x14000 0x280 nfsidl nfsio
20778 507212 0 0 3 0x14000 0x280 nfsidl nfsio
30064 204351 0 0 3 0x14000 0x280 nfsidl nfsio
72777 298515 56103 0 3 0x2 0x80 wait syz-executor
66394 188306 56103 0 3 0x2 0x80 nanoslp syz-executor
17115 157574 56103 0 3 0x2 0x80 piperd syz-executor
64631 51292 1 0 3 0x100003 0x80 ttyin getty
* 1301 4732 56103 0 7 0x2 0 syz-executor
47537 154478 56103 0 3 0x2 0x80 piperd syz-executor
33256 3280 56103 0 3 0x2 0x80 piperd syz-executor
91098 156122 56103 0 3 0x2 0x80 wait syz-executor
56103 430182 1 0 2 0x2 0 syz-executor
16523 343936 0 0 3 0x14000 0x200 bored smr
51480 489606 0 0 2 0x14000 0x200 zerothread
93401 77567 0 0 3 0x14000 0x200 aiodoned aiodoned
85023 457445 0 0 3 0x14000 0x200 syncer update
16348 168136 0 0 3 0x14000 0x200 cleaner cleaner
39493 335076 0 0 3 0x14000 0x200 reaper reaper
44489 56609 0 0 3 0x14000 0x200 pgdaemon pagedaemon
11292 63092 0 0 3 0x14000 0x200 bored viomb
85061 355072 0 0 3 0x14000 0x40000200 acpi0 acpi0
36950 363104 0 0 7 0x14000 0x40000200 idle1
36407 244359 0 0 3 0x14000 0x200 bored softnet1
27823 231886 0 0 3 0x14000 0x200 bored softnet0
36781 73550 0 0 3 0x14000 0x200 bored systqmp
19144 213368 0 0 3 0x14000 0x200 bored systq
60238 268394 0 0 3 0x14000 0x200 tmoslp softclockmp
5798 238521 0 0 2 0x14000 0x40000200 softclock
77031 517134 0 0 3 0x14000 0x40000200 idle0
1 299446 0 0 3 0x2 0x80 wait init
0 0 -1 0 3 0x10000 0x200 scheduler swapper
ddb{0}> show all locks
Process 1301 (syz-executor) thread 0xffff800045fef240 (4732)
exclusive rrwlock inode r = 0 (0xfffff1806c0ddeb8)
#0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1 rw_do_enter_write+0x419 sys/kern/kern_rwlock.c:320
#2 rrw_enter+0xc6 sys/kern/kern_rwlock.c:621
#3 VOP_LOCK+0xbd sys/kern/vfs_vops.c:527
#4 vn_lock+0xa4 sys/kern/vfs_vnops.c:576
#5 vget+0x2a2 sys/kern/vfs_subr.c:692
#6 ufs_ihashget+0x185 sys/ufs/ufs/ufs_ihash.c:98
#7 ffs_vget+0x8c sys/ufs/ffs/ffs_vfsops.c:1203
#8 ufs_lookup+0x1a36 sys/ufs/ufs/ufs_lookup.c:478
#9 VOP_LOOKUP+0x6e sys/kern/vfs_vops.c:85
#10 vfs_lookup+0x963 sys/kern/vfs_lookup.c:580
#11 namei+0x7c5 sys/kern/vfs_lookup.c:250
#12 dounlinkat+0xc1 sys/kern/vfs_syscalls.c:1807
#13 syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#13 syscall+0xb17 sys/arch/amd64/amd64/trap.c:791
#14 Xsyscall+0x128
exclusive rrwlock inode r = 0 (0xfffff1806d28db20)
#0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1 rw_do_enter_write+0x419 sys/kern/kern_rwlock.c:320
#2 rrw_enter+0xc6 sys/kern/kern_rwlock.c:621
#3 VOP_LOCK+0xbd sys/kern/vfs_vops.c:527
#4 vn_lock+0xa4 sys/kern/vfs_vnops.c:576
#5 vfs_lookup+0x12b sys/kern/vfs_lookup.c:431
#6 namei+0x7c5 sys/kern/vfs_lookup.c:250
#7 dounlinkat+0xc1 sys/kern/vfs_syscalls.c:1807
#8 syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#8 syscall+0xb17 sys/arch/amd64/amd64/trap.c:791
#9 Xsyscall+0x128
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff83b22f00)
#0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1 syscall+0xaf4 mi_syscall sys/sys/syscall_mi.h:175 [inline]
#1 syscall+0xaf4 sys/arch/amd64/amd64/trap.c:791
#2 Xsyscall+0x128
ddb{0}> show malloc
Type InUse MemUse HighUse Limit Requests Type Lim
devbuf 11049 12017K 12157K 166960K 12233 0
pcb 50 14K 14K 166960K 84 0
rtable 227 7K 8K 166960K 592 0
pf 37 18K 19K 166960K 70 0
ifaddr 40 6K 7K 166960K 78 0
ifgroup 55 2K 2K 166960K 91 0
sysctl 1 1K 9K 166960K 6 0
counters 70 37K 37K 166960K 94 0
ioctlops 0 0K 4K 166960K 1583 0
iov 0 0K 12K 166960K 8 0
mount 1 1K 1K 166960K 1 0
log 4 20K 20K 166960K 8 0
vnodes 1290 81K 81K 166960K 1514 0
UFS quota 1 32K 32K 166960K 1 0
UFS mount 5 36K 36K 166960K 5 0
shm 2 1K 5K 166960K 4 0
VM map 2 1K 1K 166960K 2 0
sem 13 0K 1K 166960K 17 0
dirhash 12 2K 2K 166960K 12 0
ACPI 1692 195K 286K 166960K 12470 0
file desc 13 49K 97K 166960K 370 0
sigio 0 0K 0K 166960K 3 0
proc 21 33K 147K 166960K 799 0
subproc 72 4K 4K 166960K 144 0
NFS srvsock 1 0K 0K 166960K 1 0
NFS daemon 1 16K 16K 166960K 1 0
ip_moptions 0 0K 0K 166960K 12 0
in_multi 88 5K 6K 166960K 178 0
ether_multi 1 0K 0K 166960K 1 0
mrt 0 0K 0K 166960K 12 0
ISOFS mount 1 32K 32K 166960K 1 0
MSDOSFS mount 1 16K 16K 166960K 1 0
ttys 73 334K 334K 166960K 73 0
exec 0 0K 1K 166960K 574 0
fusefs mount 1 32K 32K 166960K 1 0
tdb 3 0K 0K 166960K 3 0
VM swap 8 62K 64K 166960K 10 0
UVM amap 104 82K 177K 166960K 4940 0
UVM aobj 9 2K 2K 166960K 9 0
pinsyscall 16 32K 108K 166960K 1755 0
memdesc 1 4K 4K 166960K 1 0
crypto data 1 1K 1K 166960K 1 0
NDP 16 0K 1K 166960K 52 0
temp 41 9119K 9158K 166960K 16532 0
kqueue 1 2K 26K 166960K 51 0
SYN cache 2 16K 16K 166960K 2 0
ddb{0}> show all pools
Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
plcache 128 28 0 0 1 0 1 1 0 8 0
rtpcb 120 54 0 54 1 0 1 1 0 8 1
rtentry 176 190 0 90 6 0 6 6 0 8 0
unpcb 144 103 0 103 1 0 1 1 0 8 1
syncache 336 5 0 5 2 1 1 1 0 8 1
tcpcb 736 38 0 37 1 0 1 1 0 8 0
arp 136 32 0 16 1 0 1 1 0 8 0
inpcb 328 210 0 175 4 0 4 4 0 8 0
nd6 152 47 0 25 1 0 1 1 0 8 0
pkpcb 40 2 0 2 1 0 1 1 0 8 1
kcovpl 48 16 0 8 1 0 1 1 0 8 0
ppxss 1192 4 0 4 1 0 1 1 0 8 1
pfstscr 40 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 45 0 0 1 0 1 1 0 8 0
pfstkey 128 57 0 12 2 0 2 2 0 8 0
pfstate 448 49 0 6 5 0 5 5 0 8 0
pfrule 1360 22 0 15 2 0 2 2 0 8 0
art_heap8 4096 1 0 0 1 0 1 1 0 8 0
art_heap4 256 779 0 365
Struck through repros no longer work on HEAD.