syzbot


uvm_fault: ufsdirhash_lookup

Status: upstream: reported on 2026/03/26 23:00
Reported-by: syzbot+d1662df96d7c0eca078f@syzkaller.appspotmail.com
First crash: 65d, last: 6d01h

Sample crash report:
uvm_fault(0xffffffff839d3278, 0xffff800029d6211c, 0, 1) -> d
kernel: page fault trap, code=0
Stopped at      ufsdirhash_lookup+0x6d0:        movzwl  0x4(%rax,%r14,1),%r12d
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*109923  26279      0           0  0x4000000    0  syz-executor
ufsdirhash_lookup(fffffd807c382200,ffff80002a749402,3,fffffd807c3822bc,ffff80003c52d320,ffff80003c52d32c) at ufsdirhash_lookup+0x6d0 sys/ufs/ufs/ufs_dirhash.c:407
ufs_lookup() at ufs_lookup+0xf66 sys/ufs/ufs/ufs_lookup.c:214
VOP_LOOKUP(fffffd80622550e8,ffff80003c52d678,ffff80003c52d6a8) at VOP_LOOKUP+0x6e sys/kern/vfs_vops.c:85
vfs_lookup(ffff80003c52d648) at vfs_lookup+0x94a sys/kern/vfs_lookup.c:580
namei(ffff80003c52d648) at namei+0x7c3 sys/kern/vfs_lookup.c:250
dorenameat(ffff80002a737c90,ffffff9c,200000000a40,ffffff9c,200000000680) at dorenameat+0x91 sys/kern/vfs_syscalls.c:3026
syscall(ffff80003c52d830) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c52d830) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x30b3e8ed2e0, count: 7
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> 
ddb> set $lines = 0
ddb> set $maxwidth = 0
ddb> show panic
*cpu0: uvm_fault(0xffffffff839d3278, 0xffff800029d6211c, 0, 1) -> d
ddb> trace
ufsdirhash_lookup(fffffd807c382200,ffff80002a749402,3,fffffd807c3822bc,ffff80003c52d320,ffff80003c52d32c) at ufsdirhash_lookup+0x6d0 sys/ufs/ufs/ufs_dirhash.c:407
ufs_lookup() at ufs_lookup+0xf66 sys/ufs/ufs/ufs_lookup.c:214
VOP_LOOKUP(fffffd80622550e8,ffff80003c52d678,ffff80003c52d6a8) at VOP_LOOKUP+0x6e sys/kern/vfs_vops.c:85
vfs_lookup(ffff80003c52d648) at vfs_lookup+0x94a sys/kern/vfs_lookup.c:580
namei(ffff80003c52d648) at namei+0x7c3 sys/kern/vfs_lookup.c:250
dorenameat(ffff80002a737c90,ffffff9c,200000000a40,ffffff9c,200000000680) at dorenameat+0x91 sys/kern/vfs_syscalls.c:3026
syscall(ffff80003c52d830) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c52d830) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x30b3e8ed2e0, count: -8
ddb> show registers
rdi               0xffff80002a8a4000
rsi                             0xf4
rbp               0xffff80003c52d2d0
rbx               0xfffffd8065dabc10
rdx               0xffff80002a8a4000
rcx                             0xf3
rax               0xffff800029d62000
r8                0xffffffffffffffff
r9                0xffff80003c52d32c
r10               0x2dc9cc153fbe1e32
r11               0x62ac7d7ae529e297
r12                                0
r13               0xffff800029d62000
r14                            0x118
r15                            0x118
rip               0xffffffff822695c0    ufsdirhash_lookup+0x6d0
cs                               0x8
rflags                       0x10206    __ALIGN_SIZE+0xf206
rsp               0xffff80003c52d1f0
ss                              0x10
ufsdirhash_lookup+0x6d0:        movzwl  0x4(%rax,%r14,1),%r12d
ddb> show proc
PROC (syz-executor) tid=109923 pid=26279 tcnt=2 stat=onproc
    flags process=0 proc=4000000<THREAD>
    runpri=32, usrpri=50, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80002f0b02b0,0xffff80002a736a78
    process=0xffff8000ffffb618 user=0xffff80003c528000, vmspace=0xfffffd807c4b4cf8
    estcpu=36, cpticks=2, pctcpu=0.0, user=0, sys=2, intr=0
ddb> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 27383  128370  19323      0  2           0                syz-executor
 27383  150576  19323      0  3   0x4000080  fsleep        syz-executor
 26279   51803  38207      0  2           0                syz-executor
*26279  109923  38207      0  7   0x4000000                syz-executor
 58029  226739  50478      0  2           0                syz-executor
 58029  424642  50478      0  3   0x4000080  fsleep        syz-executor
 65318  114545  58101      0  3        0x80  nanoslp       syz-executor
 65318  523814  58101      0  3   0x4000080  kqread        syz-executor
 65318   28244  58101      0  3   0x4000080  fsleep        syz-executor
 86522  427578  84028      0  2       0xc80                syz-executor
 86522   73326  84028      0  3   0x4000080  ttybg         syz-executor
 86522  241100  84028      0  3   0x4000080  fsleep        syz-executor
 86522   90942  84028      0  3   0x4000080  fsleep        syz-executor
 57513  136904      0      0  3     0x14200  acct          acct
 50478  414106  57352      0  2       0xc82                syz-executor
 74749  471393      1      0  3        0x80  nanoslp       init
 19323  363257  57352      0  2       0xc82                syz-executor
 58101  497462  57352      0  2       0xc82                syz-executor
 84028  194606  57352      0  2       0xc82                syz-executor
 96570  490561  57352      0  2       0xc82                syz-executor
 38207  478206  57352      0  2       0xc82                syz-executor
 57352   66158  22711      0  3        0x82  wait          syz-executor
 22711  169763  25063      0  3    0x10008a  sigsusp       ksh
 25063  295919  23594      0  3        0x98  kqread        sshd-session
 23594  479928   3242      0  3        0x92  kqread        sshd-session
  3242  519132      1      0  3        0x88  kqread        sshd
 29519  103045  37863     73  3   0x1100090  kqread        syslogd
 37863  248696      1      0  3    0x100082  sbwait        syslogd
 25898  109582      1      0  3    0x100080  kqread        resolvd
 75180  149401  78109     77  3    0x100092  kqread        dhcpleased
 16799  332630  78109     77  3    0x100092  kqread        dhcpleased
 78109   31675      1      0  3        0x80  kqread        dhcpleased
 87235  430436      0      0  3     0x14200  bored         smr
 31081  244909      0      0  2     0x14200                zerothread
 69483  413017      0      0  3     0x14200  aiodoned      aiodoned
 19415  226869      0      0  3     0x14200  syncer        update
 10629  364040      0      0  3     0x14200  cleaner       cleaner
 52612  138842      0      0  3     0x14200  reaper        reaper
 72741  476500      0      0  3     0x14200  pgdaemon      pagedaemon
 35575  210988      0      0  3     0x14200  bored         viomb
 42733  483030      0      0  3  0x40014200  acpi0         acpi0
   490  522058      0      0  2     0x14200                softnet0
 33817  309716      0      0  3     0x14200  bored         systqmp
  9361  360535      0      0  3     0x14200  bored         systq
 96062  264742      0      0  3  0x40014200  tmoslp        softclock
 26347  478955      0      0  3  0x40014200                idle0
     1   89780      0      0  3        0x82  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb> show all locks
No such command
ddb> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11046  12261K   12613K 166960K     12974        0
            pcb    17     12K      12K 166960K       116        0
         rtable   197      7K      10K 166960K       517        0
             pf    32     13K      20K 166960K       166        0
         ifaddr    34      6K       7K 166960K        89        0
        ifgroup    42      1K       2K 166960K       127        0
         sysctl     3      1K       9K 166960K         7        0
       counters    31     17K      18K 166960K        74        0
       ioctlops     0      0K       4K 166960K       113        0
            iov     0      0K      17K 166960K        29        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1299     82K      82K 166960K      1879        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       5K 166960K         5        0
         VM map     2      1K       1K 166960K         2        0
            sem    19      3K       3K 166960K        31        0
        dirhash    15      2K       2K 166960K        45        0
           ACPI  1692    195K     286K 166960K     12470        0
      file desc    15     53K      93K 166960K      1010        0
          sigio     0      0K       0K 166960K        16        0
           proc    51     50K     100K 166960K       587        0
        subproc    63      3K       4K 166960K        90        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K        40        0
       in_multi    73      5K       7K 166960K       163        0
    ether_multi     1      0K       0K 166960K        18        0
            mrt     0      0K       0K 166960K        42        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys   103    466K     466K 166960K       103        0
           exec     0      0K       1K 166960K       435        0
   fusefs mount     1     32K      32K 166960K         1        0
     pfkey data     0      0K       0K 166960K         1        0
            tdb     3      0K       0K 166960K         3        0
        VM swap     8     62K      64K 166960K        10        0
       UVM amap   201    138K     165K 166960K      9903        0
       UVM aobj     5      2K       2K 166960K         6        0
     pinsyscall    35     70K      94K 166960K      2182        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
    ip6_options     0      0K       0K 166960K        41        0
            NDP     9      0K       2K 166960K        58        0
           temp    38   9104K    9232K 166960K     24932        0
         kqueue    14     22K      27K 166960K       164        0
      SYN cache     2     16K      16K 166960K         2        0
ddb> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
rtpcb      120       50    0       47     1     0     1     1     0     8    0
rtentry    136      157    0       73     4     0     4     4     0     8    0
unpcb      144      242    0      227     1     0     1     1     0     8    0
syncache   336        9    0        9     2     1     1     1     0     8    1
tcpcb      736       87    0       83     1     0     1     1     0     8    0
arp         96       24    0        9     1     0     1     1     0     8    0
ipq         40        2    0        0     1     0     1     1     0     8    0
ipqe        40        2    0        0     1     0     1     1     0     8    0
inpcb      328      351    0      342     2     1     1     2     0     8    0
ip6q        72        1    0        0     1     0     1     1     0     8    0
ip6af       40        1    0        0     1     0     1     1     0     8    0
nd6        112       31    0       15     1     0     1     1     0     8    0
pkpcb       40        1    0        1     1     0     1     1     0     8    1
kcovpl      48       10    0        3     1     0     1     1     0     8    0
ppxss      1072      32    0       32     2     1     1     1     0     8    1
pppxif     1416       6    0        6     1     0     1     1     0     8    1
pfstscr     40       11    0        6     2     1     1     1     0     8    0
pfrktable  1344      17    0       16     1     0     1     1     0     8    0
pfanchor   1288       9    0        6     1     0     1     1     0     8    0
pftag       88        7    0        3     1     0     1     1     0     8    0
pfstitem    24       12    0        4     1     0     1     1     0     8    0
pfstkey    128       19    0        7     1     0     1     1     0     8    0
pfstate    384       10    0        6     1     0     1     1     0     8    0
pfrule     1360      18    0       17     1     0     1     1     0     8    0
rttmr      136        5    0        5     2     1     1     1     0     8    1
art_heap8  4096       1    0        0     1     0     1     1     0     8    0
art_heap4  256      745    0      397    33     2    31    31     0     8    3
art_table   40      746    0      397     5     0     5     5     0     8    0
art_node    32      157    0       83     1     0     1     1     0     8    0
sysvmsgpl   40       11    0        3     1     0     1     1     0     8    0
semupl     112        3    0        3     2     1     1     1     0     8    1
semapl      72       25    0        8     1     0     1     1     0     8    0
shmpl      112        3    0        1     1     0     1     1     0     8    0
dirhash    1024      39    0       20     3     0     3     3     0     8    0
dino2pl    256     3007    0     1546    92     0    92    92     0     8    0
ffsino     256     3008    0     1547    92     0    92    92     0     8    0
nchpl      144     4163    0     2467    64     0    64    64     0     8    0
rtmask      32        1    0        1     1     0     1     1     0     8    1
vnodes     216     3340    0        0   186     0   186   186     0     8    0
namei      1024   11854    0    11853     3     2     1     2     0     8    0
pfiaddrpl  120        4    0        4     1     0     1     1     0     8    1
acpiwqpl    32        1    0        1     1     0     1     1     1     8    1
kstatmem   264       75    0       56     2     0     2     2     0     8    0
scsiplug    72        6    0        6     2     1     1     1     0     8    1
scxspl     216    17246    0    17246     8     7     1     8     1     8    1
plimitpl   152      164    0      147     1     0     1     1     0     8    0
sigapl     424     1307    0     1265     7     1     6     6     0     8    0
knotepl    120    32546    0    32498    16     6    10    10     0     8    8
kqueuepl   184      173    0      163     1     0     1     1     0     8    0
pipepl     304      148    0      121     3     0     3     3     0     8    0
fdescpl    448     1293    0     1266     5     1     4     5     0     8    0
filepl     120     4337    0     4137     7     0     7     7     0     8    0
lockfpl    104      239    0      237     1     0     1     1     0     8    0
lockfspl    48      103    0      101     1     0     1     1     0     8    0
sessionpl  144       53    0       46     1     0     1     1     0     8    0
pgrppl      48       64    0       49     1     0     1     1     0     8    0
ucredpl    104     1033    0     1021     1     0     1     1     0     8    0
zombiepl   144     1268    0     1265     2     1     1     1     0     8    0
processpl  1152    1307    0     1265     4     0     4     4     0     8    0
procpl     664     2282    0     2232     5     0     5     5     0     8    0
sosppl     176        2    0        2     1     0     1     1     0     8    1
sockpl     552      647    0      620     3     0     3     3     0     8    1
mcl64k     65536    450    0      450     2     1     1     1     0     8    1
mcl16k     16384    216    0      216     2     1     1     1     0     8    1
mcl12k     12288    107    0      107     2     1     1     1     0     8    1
mcl9k128   9344      37    0       37     2     1     1     1     0     8    1
mcl8k      8192     131    0      131     2     1     1     1     0     8    1
mcl4k      4096    4259    0     4208    15     7     8    14     0     8    1
mcl2k2     2112       1    0        1     1     1     0     1     0     8    0
mcl2k      2048     449    0      445     2     1     1     2     0     8    0
mtagpl      96       21    0        9     1     0     1     1     0     8    0
mbufpl     256    15102    0    14957    21     7    14    19     0     8    1
bufpl      280     6738    0      522   445     0   445   445     0     8    0
anonpl      24   163989    0   161047    67    12    55    55     0   186   24
amapchunkpl 152   32038    0    31614    33     7    26    27     0   158    6
amappl16   200     2735    0     2706    23    10    13    21     0     8    8
amappl15   192        5    0        5     1     1     0     1     0     8    0
amappl14   184      435    0      434     1     0     1     1     0     8    0
amappl13   176      124    0      115     1     0     1     1     0     8    0
amappl12   168     1543    0     1518     2     0     2     2     0     8    0
amappl11   160        8    0        8     1     1     0     1     0     8    0
amappl10   152       59    0       49     1     0     1     1     0     8    0
amappl9    144      267    0      267     1     1     0     1     0     8    0
amappl8    136       99    0       98     1     0     1     1     0     8    0
amappl7    128      145    0      134     1     0     1     1     0     8    0
amappl6    120      167    0      166     1     0     1     1     0     8    0
amappl5    112       95    0       88     1     0     1     1     0     8    0
amappl4    104      284    0      269     1     0     1     1     0     8    0
amappl3     96     6864    0     6769     4     1     3     4     0     8    0
amappl2     88      564    0      515     2     0     2     2     0     8    0
amappl1     80    14422    0    13900    16     1    15    15     0     8    1
amappl      88     9119    0     8975     5     1     4     5     0    92    0
uvmvnodes   80      122    0        0     3     0     3     3     0     8    0
dma8192    8192       1    0        1     1     1     0     1     0     8    0
dma4096    4096       1    0        1     1     1     0     1     0     8    0
dma2048    2048       2    0        2     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      256    0      256     2     1     1     1     0     8    1
dma64       64        6    0        6     1     1     0     1     0     8    0
dma32       32        8    0        8     1     1     0     1     0     8    0
dma16       16       20    0       19     1     0     1     1     0     8    0
aobjpl      72        5    0        1     1     0     1     1     0     8    0
uaddrrnd    24     1293    0     1266     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24     1293    0     1266     1     0     1     1     0     8    0
vmmpekpl   168    10515    0    10468     4     1     3     3     0     8    0
vmmpepl    168    86499    0    84843    99     4    95    95     0   357    9
vmsppl     368     1292    0     1266     4     1     3     4     0     8    0
rwobjpl     40    23555    0    22656    14     0    14    14     0     8    2
pdppl      4096    2592    0     2532   106    36    70    80     0     8   10
pvpl        32   602920    0   593669   178    19   159   159     0   265   57
pmappl     216     1292    0     1266     3     0     3     3     0     8    0
extentpl    40       45    0       27     1     0     1     1     0     8    0
phpool     112      392    0       65    10     0    10    10     0     8    0
ddb> machine ddbcpu 0
No such command
ddb> trace
ufsdirhash_lookup(fffffd807c382200,ffff80002a749402,3,fffffd807c3822bc,ffff80003c52d320,ffff80003c52d32c) at ufsdirhash_lookup+0x6d0 sys/ufs/ufs/ufs_dirhash.c:407
ufs_lookup() at ufs_lookup+0xf66 sys/ufs/ufs/ufs_lookup.c:214
VOP_LOOKUP(fffffd80622550e8,ffff80003c52d678,ffff80003c52d6a8) at VOP_LOOKUP+0x6e sys/kern/vfs_vops.c:85
vfs_lookup(ffff80003c52d648) at vfs_lookup+0x94a sys/kern/vfs_lookup.c:580
namei(ffff80003c52d648) at namei+0x7c3 sys/kern/vfs_lookup.c:250
dorenameat(ffff80002a737c90,ffffff9c,200000000a40,ffffff9c,200000000680) at dorenameat+0x91 sys/kern/vfs_syscalls.c:3026
syscall(ffff80003c52d830) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c52d830) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x30b3e8ed2e0, count: -8
ddb> machine ddbcpu 1
No such command
ddb> trace
ufsdirhash_lookup(fffffd807c382200,ffff80002a749402,3,fffffd807c3822bc,ffff80003c52d320,ffff80003c52d32c) at ufsdirhash_lookup+0x6d0 sys/ufs/ufs/ufs_dirhash.c:407
ufs_lookup() at ufs_lookup+0xf66 sys/ufs/ufs/ufs_lookup.c:214
VOP_LOOKUP(fffffd80622550e8,ffff80003c52d678,ffff80003c52d6a8) at VOP_LOOKUP+0x6e sys/kern/vfs_vops.c:85
vfs_lookup(ffff80003c52d648) at vfs_lookup+0x94a sys/kern/vfs_lookup.c:580
namei(ffff80003c52d648) at namei+0x7c3 sys/kern/vfs_lookup.c:250
dorenameat(ffff80002a737c90,ffffff9c,200000000a40,ffffff9c,200000000680) at dorenameat+0x91 sys/kern/vfs_syscalls.c:3026
syscall(ffff80003c52d830) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c52d830) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x30b3e8ed2e0, count: -8

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/25 02:22 openbsd 3ca1fbf96c86 c69befb3 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufsdirhash_lookup
2026/05/05 23:27 openbsd 83f5cd019021 340bcdf0 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore uvm_fault: ufsdirhash_lookup
2026/03/26 22:59 openbsd 9c6370df4fcd 4b3d9a38 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore uvm_fault: ufsdirhash_lookup
* Struck through repros no longer work on HEAD.