uvm_fault: ufs_readdir

Status: upstream: reported on 2026/05/26 22:30
Reported-by: syzbot+f60de315eda5f53c0057@syzkaller.appspotmail.com
First crash: 61d, last: 2d13h

Sample crash report:
uvm_fault(0xffffffff83a0d4d0, 0xffff800020f72004, 0, 1) -> d
kernel: page fault trap, code=0
Stopped at      ufs_readdir+0x26e:      movzwl  0x4(%r14),%ebx
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*356320   3663      0         0x2          0    0  syz-executor
ufs_readdir(ffff80002a8a3200) at ufs_readdir+0x26e sys/ufs/ufs/ufs_vnops.c:1397
VOP_READDIR(fffff2006d192dc8,ffff80002a8a3288,fffff20007ffd548,ffff80002a8a32cc) at VOP_READDIR+0x125 sys/kern/vfs_vops.c:453
sys_getdents(ffff80002a7362a0,ffff80002a8a3410,ffff80002a8a3360) at sys_getdents+0x2dd sys/kern/vfs_syscalls.c:3133
syscall(ffff80002a8a3410) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a8a3410) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7bccc6ee3ed0, count: 10
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(0xffffffff83a0d4d0, 0xffff800020f72004, 0, 1) -> d
ddb> show kasan
No such command
ddb> trace
ufs_readdir(ffff80002a8a3200) at ufs_readdir+0x26e sys/ufs/ufs/ufs_vnops.c:1397
VOP_READDIR(fffff2006d192dc8,ffff80002a8a3288,fffff20007ffd548,ffff80002a8a32cc) at VOP_READDIR+0x125 sys/kern/vfs_vops.c:453
sys_getdents(ffff80002a7362a0,ffff80002a8a3410,ffff80002a8a3360) at sys_getdents+0x2dd sys/kern/vfs_syscalls.c:3133
syscall(ffff80002a8a3410) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a8a3410) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7bccc6ee3ed0, count: -5
ddb> show registers
rdi                            0x200
rsi                            0x800
rbp               0xffff80002a8a31f0
rbx                            0x200
rdx                                0
rcx               0xfffff200691d6370
rax               0xffff800020f72200
r8                0xffffffffffffffff
r9                               0x3
r10               0xfbc4937f57890179
r11               0x90b19c7fa69ed393
r12                                0
r13               0xffff80002a8a3288
r14               0xffff800020f72000
r15               0xffff800020f72008
rip               0xffffffff82e89eae    ufs_readdir+0x26e
cs                               0x8
rflags                       0x10283    __ALIGN_SIZE+0xf283
rsp               0xffff80002a8a3040
ss                              0x10
ufs_readdir+0x26e:      movzwl  0x4(%r14),%ebx
ddb> show proc
PROC (syz-executor) tid=356320 pid=3663 tcnt=1 stat=onproc
    flags process=2<EXEC> proc=0
    runpri=32, usrpri=50, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80002a736f98,0xffff80003c8fb4f0
    process=0xffff80002a79f610 user=0xffff80002a89e000, vmspace=0xfffff2006fa43458
    estcpu=36, cpticks=10, pctcpu=0.1, user=0, sys=10, intr=0
ddb> ps
   PID     TID   PPID   UID  S      PRLAGS     PFLAGS WAIT      COMMAND
 96541  129446  86706     0  2           0      0xc80           syz-executor
 96541  210060  86706     0  3           0  0x4000080 lockf     syz-executor
 96541  226724  86706     0  3           0  0x4000080 fsleep    syz-executor
 96541  372098  86706     0  3           0  0x4000080 fsleep    syz-executor
 86935  100308  74337     0  3           0       0x80 nanoslp   syz-executor
 86935  520474  74337     0  3           0  0x4000088 kqpoll    syz-executor
 86935  285204  74337     0  3           0  0x4000080 fsleep    syz-executor
 72970  112376      0     0  3     0x14000      0x280 nfsidl    nfsio
 81050  147185      0     0  3     0x14000      0x280 nfsidl    nfsio
 37712  476461      0     0  3     0x14000      0x280 nfsidl    nfsio
 43939  229254      0     0  3     0x14000      0x280 nfsidl    nfsio
 62053   42514      0     0  3     0x14000      0x280 nfsidl    nfsio
 13066  170939      0     0  3     0x14000      0x280 nfsidl    nfsio
 84176  314808      0     0  3     0x14000      0x280 nfsidl    nfsio
 34668   76020      0     0  3     0x14000      0x280 nfsidl    nfsio
  3910  156524      0     0  3     0x14000      0x280 nfsidl    nfsio
 79408  475803      0     0  3     0x14000      0x280 nfsidl    nfsio
 78925  500122      0     0  3     0x14000      0x280 nfsidl    nfsio
 54906  163224      0     0  3     0x14000      0x280 nfsidl    nfsio
 70584    1176      0     0  3     0x14000      0x280 nfsidl    nfsio
 80082   61123      0     0  3     0x14000      0x280 nfsidl    nfsio
 87543  508468      0     0  3     0x14000      0x280 nfsidl    nfsio
 99122  479304      0     0  3     0x14000      0x280 nfsidl    nfsio
 29622  157341      0     0  3     0x14000      0x280 nfsidl    nfsio
 77793  208209      0     0  3     0x14000      0x280 nfsidl    nfsio
  9147  518574      0     0  3     0x14000      0x280 nfsidl    nfsio
 85484  479187      0     0  3     0x14000      0x280 nfsidl    nfsio
 96586  270093      1     0  3    0x100003       0x80 ttyin     getty
 42105  420735      0     0  3     0x14000      0x200 acct      acct
* 3663  356320   9386     0  7         0x2          0           syz-executor
 59319   39920   9386     0  3         0x2       0x80 nanoslp   syz-executor
 74337  167694   9386     0  3         0x2       0x80 nanoslp   syz-executor
 86706   94556   9386     0  3         0x2       0x80 nanoslp   syz-executor
  9386  401594      1     0  3         0x2       0x80 wait      syz-executor
 74990  296046      1    73  3   0x1100010       0x80 kqread    syslogd
 35080  132496      0     0  3     0x14000      0x200 bored     smr
 28181  184735      0     0  2     0x14000      0x200           zerothread
 76270  336965      0     0  3     0x14000      0x200 aiodoned  aiodoned
 70821  149023      0     0  3     0x14000      0x200 syncer    update
 65559  347105      0     0  3     0x14000      0x200 cleaner   cleaner
 35211  332699      0     0  3     0x14000      0x200 reaper    reaper
  7025  248181      0     0  3     0x14000      0x200 pgdaemon  pagedaemon
 28370  199718      0     0  3     0x14000      0x200 bored     viomb
 97131  256644      0     0  3     0x14000 0x40000200 acpi0     acpi0
  8182  416983      0     0  3     0x14000      0x200 bored     softnet0
 45949  245081      0     0  3     0x14000      0x200 bored     systqmp
 92252   43338      0     0  3     0x14000      0x200 bored     systq
 81689   73529      0     0  3     0x14000 0x40000200 tmoslp    softclock
 83863   78447      0     0  3     0x14000 0x40000200           idle0
     1  272572      0     0  3         0x2       0x80 wait      init
     0       0     -1     0  3     0x10000      0x200 scheduler swapper
ddb> show all locks
No such command
ddb> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11031  12101K   12573K 166960K     13088        0
            pcb    17     14K      16K 166960K        92        0
         rtable   224      7K      10K 166960K       413        0
             pf    34     13K      19K 166960K        92        0
         ifaddr    40      6K       7K 166960K        60        0
        ifgroup    54      2K       2K 166960K        84        0
         sysctl     4      1K       9K 166960K         9        0
       counters    34     17K      18K 166960K        49        0
       ioctlops     0      0K       4K 166960K       195        0
            iov     0      0K      20K 166960K        19        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1393     88K      88K 166960K      1832        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       9K 166960K         8        0
         VM map     2      1K       1K 166960K         2        0
            sem    12      0K       0K 166960K        95        0
        dirhash    12      2K       2K 166960K        21        0
           ACPI  1734    201K     291K 166960K     11964        0
      file desc    13     45K      97K 166960K       531        0
          sigio     0      0K       0K 166960K         4        0
           proc    20     25K     124K 166960K       564        0
        subproc    72      4K       4K 166960K        72        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K        47        0
       in_multi    88      6K       7K 166960K       112        0
    ether_multi     1      0K       0K 166960K         4        0
            mrt     0      0K       0K 166960K        20        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
         

Crashes (153):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/25 04:33 openbsd f3d8a5574675 492bab15 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/23 15:16 openbsd 6c9531571979 71a13572 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/23 09:36 openbsd 7df8bae8aea9 881ce5c2 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/22 23:06 openbsd 7df8bae8aea9 881ce5c2 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/22 10:31 openbsd 9107f2bc3d03 4a865b71 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/21 16:34 openbsd 20200149c668 7c5de9c3 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/20 22:32 openbsd d55fd7dd01df de6a700d .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/19 01:17 openbsd fc1b4e4caf7d 72524a66 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/18 13:34 openbsd bc321d44d2f5 72524a66 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/18 08:41 openbsd 97f4e10dc0be 72524a66 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/17 20:02 openbsd 94b919120046 7f27c57a .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/17 12:13 openbsd 94b919120046 7f27c57a .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/17 05:55 openbsd 5f0b8e1b9eb7 6ca2b51a .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/15 11:47 openbsd af68cf7bb0f1 a4ed0f4f .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/14 09:46 openbsd ddde2be8d3c6 2130f682 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/13 15:24 openbsd 663dfdac4969 a870962e .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/12 16:16 openbsd e38f82204f65 d78ea535 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/12 14:41 openbsd e38f82204f65 d78ea535 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/10 17:06 openbsd 217e59b7506d 99e64375 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/08 01:00 openbsd 59464ad990e2 88a4b44c .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/07 13:39 openbsd afaaa4e34da1 fcece630 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/07 10:44 openbsd afaaa4e34da1 fcece630 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/06 13:06 openbsd a8064a9ef4c0 fcece630 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/06 10:35 openbsd a8064a9ef4c0 fcece630 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/05 21:25 openbsd 549eb3d3b3c2 fcece630 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/05 14:30 openbsd e9996feb4a0b fcece630 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/04 01:21 openbsd 2f91687338ee aa437a8a .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/03 15:05 openbsd 2f91687338ee aa437a8a .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/01 23:21 openbsd 927838563536 5fb9973c .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/01 16:43 openbsd 927838563536 5fb9973c .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/07/01 13:42 openbsd 927838563536 5fb9973c .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/29 02:12 openbsd a0c937b71e27 fb92f11c .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/27 09:25 openbsd 309f6120392c fb92f11c .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/25 09:09 openbsd 7c9581f1cd1a cfa969bf .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/25 02:19 openbsd 7c9581f1cd1a cfa969bf .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/25 01:00 openbsd 7c9581f1cd1a cfa969bf .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/24 18:18 openbsd aea2b55f2b77 c1da772e .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/24 16:06 openbsd aea2b55f2b77 c1da772e .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/24 11:29 openbsd aea2b55f2b77 c1da772e .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/24 08:50 openbsd 26c6eebc6662 042555ff .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/24 02:40 openbsd 26c6eebc6662 042555ff .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/23 23:16 openbsd 26c6eebc6662 042555ff .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/23 21:15 openbsd 26c6eebc6662 042555ff .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/06/23 11:45 openbsd a7fbd22dd6cd 4b1d8f01 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
2026/05/26 22:30 openbsd 51e8ce08d8c9 2b01f00e .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: ufs_readdir
* Struck through repros no longer work on HEAD.