syzbot

uvm_fault(0xffffffff83a72490, 0xffff800020cb2004, 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
*240919  75756      0         0x2          0    0  syz-executor
ufs_readdir(ffff80002a8676a0) at ufs_readdir+0x26e sys/ufs/ufs/ufs_vnops.c:1397
VOP_READDIR(fffffd00700136e8,ffff80002a867728,fffffd0007ffd8f0,ffff80002a86776c) at VOP_READDIR+0x125 sys/kern/vfs_vops.c:453
sys_getdents(ffff80002a736008,ffff80002a8678b0,ffff80002a867800) at sys_getdents+0x2dd sys/kern/vfs_syscalls.c:3132
syscall(ffff80002a8678b0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a8678b0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x77f61900cfd0, 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(0xffffffff83a72490, 0xffff800020cb2004, 0, 1) -> d
ddb> trace
ufs_readdir(ffff80002a8676a0) at ufs_readdir+0x26e sys/ufs/ufs/ufs_vnops.c:1397
VOP_READDIR(fffffd00700136e8,ffff80002a867728,fffffd0007ffd8f0,ffff80002a86776c) at VOP_READDIR+0x125 sys/kern/vfs_vops.c:453
sys_getdents(ffff80002a736008,ffff80002a8678b0,ffff80002a867800) at sys_getdents+0x2dd sys/kern/vfs_syscalls.c:3132
syscall(ffff80002a8678b0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a8678b0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x77f61900cfd0, count: -5
ddb> show registers
rdi                            0x200
rsi                            0x800
rbp               0xffff80002a867690
rbx                            0x200
rdx                                0
rcx               0xfffffd006a200f30
rax               0xffff800020cb2200
r8                0xffffffffffffffff
r9                               0x2
r10               0xecade927a42d0126
r11               0x88fae52ea457114e
r12                                0
r13               0xffff80002a867728
r14               0xffff800020cb2000
r15               0xffff800020cb2008
rip               0xffffffff81380c1e    ufs_readdir+0x26e
cs                               0x8
rflags                       0x10283    __ALIGN_SIZE+0xf283
rsp               0xffff80002a8674e0
ss                              0x10
ufs_readdir+0x26e:      movzwl  0x4(%r14),%ebx
ddb> show proc
PROC (syz-executor) tid=240919 pid=75756 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=0xffff80002a737c90,0xffff80002a737240
    process=0xffff80002a79ed10 user=0xffff80002a862000, vmspace=0xfffffd0070315458
    estcpu=36, cpticks=3, pctcpu=0.1, user=0, sys=3, intr=0
ddb> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 15751  307400  83130      0  2    0x100000                sh
 83130  268109  29933      0  3    0x10008a  sigsusp       sh
 35636  356151  73557      0  2           0                syz-executor
 35636  180129  73557      0  3   0x4000080  fsleep        syz-executor
 91100  234940  99725      0  2           0                syz-executor
 91100  226954  99725      0  2   0x4000000                syz-executor
 23540  189056  27983      0  2           0                syz-executor
 23540  459254  27983      0  3   0x4000080  fsleep        syz-executor
 29933  315214   6937      0  3        0x82  wait          syz-executor
 95164  172386  14729      0  2       0xc80                syz-executor
 95164  434554  14729      0  3   0x4000080  ttyout        syz-executor
 95164  391114  14729      0  3   0x4000080  fsleep        syz-executor
 84928  474390      0      0  3     0x14280  nfsidl        nfsio
 52141  415073      0      0  3     0x14280  nfsidl        nfsio
  1093  310533      0      0  3     0x14280  nfsidl        nfsio
 20617   31748      0      0  3     0x14280  nfsidl        nfsio
 19407  453992      0      0  3     0x14280  nfsidl        nfsio
 64697  442808      0      0  3     0x14280  nfsidl        nfsio
 20530  325003      0      0  3     0x14280  nfsidl        nfsio
 97572  242405      0      0  3     0x14280  nfsidl        nfsio
 68330  280958      0      0  3     0x14280  nfsidl        nfsio
 25685  487554      0      0  3     0x14280  nfsidl        nfsio
 36941  280768      0      0  3     0x14280  nfsidl        nfsio
 19879  147328      0      0  3     0x14280  nfsidl        nfsio
 53353   30283      0      0  3     0x14280  nfsidl        nfsio
 78975  519596      0      0  3     0x14280  nfsidl        nfsio
 33002  156608      0      0  3     0x14280  nfsidl        nfsio
  5074  182697      0      0  3     0x14280  nfsidl        nfsio
 55013    3588      0      0  3     0x14280  nfsidl        nfsio
 96935  315852      0      0  3     0x14280  nfsidl        nfsio
  7185  187308      0      0  3     0x14280  nfsidl        nfsio
 35235  405100      0      0  3     0x14280  nfsidl        nfsio
 27983  262650   6937      0  2       0xc82                syz-executor
 13776  119624      1      0  3        0x80  nanoslp       init
 73557  233600   6937      0  3        0x82  nanoslp       syz-executor
*75756  240919   6937      0  7         0x2                syz-executor
 14729  175040   6937      0  3        0x82  nanoslp       syz-executor
 99725  309307   6937      0  2       0xc82                syz-executor
 61678  118953   6937      0  3        0x82  nanoslp       syz-executor
 59627  136663   6937      0  3        0x82  wait          syz-executor
  6937  446794      1      0  2         0x2                syz-executor
 53756  292037      0      0  3     0x14200  bored         smr
 79196  429150      0      0  2     0x14200                zerothread
 89321  176670      0      0  3     0x14200  aiodoned      aiodoned
 44986  500922      0      0  3     0x14200  syncer        update
 97143  117368      0      0  3     0x14200  cleaner       cleaner
 42046  204174      0      0  3     0x14200  reaper        reaper
 55656  463439      0      0  3     0x14200  pgdaemon      pagedaemon
 61702  235042      0      0  3     0x14200  bored         viomb
 37119    7331      0      0  3  0x40014200  acpi0         acpi0
 40854  136236      0      0  2     0x14200                softnet0
 22677  269662      0      0  3     0x14200  bored         systqmp
  5747   35914      0      0  3     0x14200  bored         systq
 94072  245051      0      0  3  0x40014200  tmoslp        softclock
  1201  450136      0      0  3  0x40014200                idle0
     1  428508      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 11024  12094K   12341K 166960K     12510        0
            pcb    17     12K      12K 166960K        81        0
         rtable   208      8K      10K 166960K       551        0
             pf    29     12K      17K 166960K        77        0
         ifaddr    36      6K       7K 166960K        80        0
        ifgroup    44      1K       2K 166960K        97        0
         sysctl     1      1K       9K 166960K         9        0
       counters    32     17K      18K 166960K        57        0
       ioctlops     0      0K       4K 166960K        98        0
            iov     0      0K      16K 166960K        42        0
          mount     1      1K       1K 166960K         1        0
            log     1      0K       0K 166960K         5        0
         vnodes  1361     86K      86K 166960K      1742        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       9K 166960K         9        0
         VM map     2      1K       1K 166960K         2        0
            sem    12      0K       0K 166960K        51        0
        dirhash    12      2K       2K 166960K        12        0
           ACPI  1692    195K     286K 166960K     12470        0
      file desc    17     65K      89K 166960K       460        0
          sigio     0      0K       0K 166960K         5        0
           proc    11     17K      83K 166960K       652        0
        subproc    72      4K       4K 166960K       117        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K        90        0
       in_multi    81      5K       7K 166960K       159        0
    ether_multi     1      0K       0K 166960K         2        0
            mrt     2      0K       0K 166960K        12        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys    79    360K     360K 166960K        79        0
           exec     0      0K       1K 166960K       447        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   130     71K     159K 166960K      5487        0
       UVM aobj     6      2K       2K 166960K         6        0
     pinsyscall    19     38K      92K 166960K      1681        0
        memdesc     1      4K       4K 166960K         1        0