syzbot


panic: vref used where vget required (2)

Status: auto-closed as invalid on 2020/08/08 03:01
Reported-by: syzbot+6cca0603d9346dce1ae0@syzkaller.appspotmail.com
First crash: 1421d, last: 1418d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
openbsd panic: vref used where vget required 1 1668d 1668d 0/3 auto-closed as invalid on 2019/12/01 17:58
openbsd panic: vref used where vget required (3) 1 821d 821d 0/3 auto-closed as invalid on 2022/03/27 19:54

Sample crash report:
panic: vref used where vget required
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*405989  78248      0           0  0x4000000    1K syz-executor.1
 420187  78248      0           0  0x4000000    0  syz-executor.1
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff822454f2) at panic+0x15c sys/kern/subr_prf.c:207
vref(fffffd806506e4e8) at vref+0x7e sys/kern/vfs_subr.c:691
namei(ffff80002318af80) at namei+0x86b sys/kern/vfs_lookup.c:329
sys_chdir(ffff800020ed8768,ffff80002318b0b8,ffff80002318b100) at sys_chdir+0x76 change_dir sys/kern/vfs_syscalls.c:851 [inline]
sys_chdir(ffff800020ed8768,ffff80002318b0b8,ffff80002318b100) at sys_chdir+0x76 sys/kern/vfs_syscalls.c:797
syscall(ffff80002318b180) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff80002318b180) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9fbb317bb60, count: 8
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{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
vref used where vget required
ddb{1}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff822454f2) at panic+0x15c sys/kern/subr_prf.c:207
vref(fffffd806506e4e8) at vref+0x7e sys/kern/vfs_subr.c:691
namei(ffff80002318af80) at namei+0x86b sys/kern/vfs_lookup.c:329
sys_chdir(ffff800020ed8768,ffff80002318b0b8,ffff80002318b100) at sys_chdir+0x76 change_dir sys/kern/vfs_syscalls.c:851 [inline]
sys_chdir(ffff800020ed8768,ffff80002318b0b8,ffff80002318b100) at sys_chdir+0x76 sys/kern/vfs_syscalls.c:797
syscall(ffff80002318b180) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff80002318b180) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9fbb317bb60, count: -7
ddb{1}> show registers
rdi               0xffffffff8198d747    db_enter+0x17
rsi                           0x16b2    __ALIGN_SIZE+0x6b2
rbp               0xffff80002318add0
rbx               0xffff80002318ae80
rdx                           0x16b3    __ALIGN_SIZE+0x6b3
rcx               0xffff800021f6e000
rax               0xffff800021f6e000
r8                0xffffffff81276dcf    kprintf+0x16f
r9                               0x1
r10                             0x25
r11               0xb23a4082aedd71a5
r12                     0x3000000008
r13               0xffff80002318ade0
r14                            0x100
r15                              0x1
rip               0xffffffff8198d748    db_enter+0x18
cs                               0x8
rflags                         0x246
rsp               0xffff80002318adc0
ss                                 0
db_enter+0x18:  addq    $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor.1) pid=405989 stat=onproc
    flags process=0 proc=4000000<THREAD>
    pri=32, usrpri=75, nice=20
    forw=0xffffffffffffffff, list=0xffff800020ed8018,0xffff800020ed89e8
    process=0xffff800020ecf358 user=0xffff800023186000, vmspace=0xfffffd807f000000
    estcpu=25, cpticks=1, pctcpu=0.0
    user=0, sys=1, intr=0
ddb{1}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 78248  499027  59159      0  2           0                syz-executor.1
*78248  405989  59159      0  7   0x4000000                syz-executor.1
 78248  157320  59159      0  2   0x4000000                syz-executor.1
 78248  356506  59159      0  3   0x4000080  netio         syz-executor.1
 78248  420187  59159      0  7   0x4000000                syz-executor.1
 42380   18672      0      0  3     0x14200  bored         sosplice
 59159  192039  83740      0  3        0x82  nanosleep     syz-executor.1
 42065  433445  83740      0  3        0x82  piperd        syz-executor.0
 83740   84844   7679      0  3        0x82  thrsleep      syz-fuzzer
 83740   93121   7679      0  3   0x4000082  nanosleep     syz-fuzzer
 83740  523642   7679      0  3   0x4000082  thrsleep      syz-fuzzer
 83740  208766   7679      0  2   0x4000002                syz-fuzzer
 83740  228888   7679      0  3   0x4000082  thrsleep      syz-fuzzer
 83740  161744   7679      0  3   0x4000082  thrsleep      syz-fuzzer
 83740  237133   7679      0  3   0x4000082  kqread        syz-fuzzer
 83740   11126   7679      0  3   0x4000082  thrsleep      syz-fuzzer
 83740  250387   7679      0  3   0x4000082  thrsleep      syz-fuzzer
 83740  173649   7679      0  3   0x4000082  thrsleep      syz-fuzzer
  7679  504961  68103      0  3    0x10008a  pause         ksh
 68103   74965   2694      0  3        0x92  select        sshd
 47499   17741      1      0  3    0x100083  ttyin         getty
  2694  235650      1      0  3        0x80  select        sshd
 57407  465729  47700     74  3    0x100092  bpf           pflogd
 47700   16647      1      0  3        0x80  netio         pflogd
 67923  423741  83988     73  3    0x100090  kqread        syslogd
 83988  320748      1      0  3    0x100082  netio         syslogd
 60090    9467      1     77  3    0x100090  poll          dhclient
 61899  254870      1      0  3        0x80  poll          dhclient
 45470  293937      0      0  3     0x14200  bored         smr
 16976   98327      0      0  3     0x14200  pgzero        zerothread
 34653   88156      0      0  3     0x14200  aiodoned      aiodoned
 27980  514709      0      0  3     0x14200  syncer        update
  4267  228819      0      0  3     0x14200  cleaner       cleaner
 30292  381249      0      0  3     0x14200  reaper        reaper
 91635  456208      0      0  3     0x14200  pgdaemon      pagedaemon
 88197  317194      0      0  3     0x14200  bored         crynlk
 74690  152931      0      0  3     0x14200  bored         crypto
  1895   32022      0      0  3  0x40014200  acpi0         acpi0
 60669  315127      0      0  3  0x40014200                idle1
  3264  429417      0      0  3     0x14200  bored         softnet
  2594  177966      0      0  3     0x14200  bored         systqmp
  1912  310046      0      0  3     0x14200  bored         systq
  3008  452419      0      0  3  0x40014200  bored         softclock
  7904  220500      0      0  3  0x40014200                idle0
     1   10799      0      0  3        0x82  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb{1}> show all locks
Process 78248 (syz-executor.1) thread 0xffff800020ed8768 (405989)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff8268a7c8)
#0  witness_lock+0x4c7 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0  witness_lock+0x4c7 sys/kern/subr_witness.c:1164
#1  __mp_acquire_count+0x51 sys/kern/kern_lock.c:227
#2  mi_switch+0x392 sys/kern/sched_bsd.c:435
#3  sleep_finish+0x113 sys/kern/kern_synch.c:418
#4  rw_enter+0x3d6 sys/kern/kern_rwlock.c:287
#5  rrw_enter+0x88 sys/kern/kern_rwlock.c:462
#6  VOP_LOCK+0x4b sys/kern/vfs_vops.c:603
#7  vn_lock+0x81 sys/kern/vfs_vnops.c:575
#8  vfs_lookup+0xe6 sys/kern/vfs_lookup.c:419
#9  namei+0x63c sys/kern/vfs_lookup.c:249
#10 sys_chdir+0x76 change_dir sys/kern/vfs_syscalls.c:851 [inline]
#10 sys_chdir+0x76 sys/kern/vfs_syscalls.c:797
#11 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#11 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570
#12 Xsyscall+0x128
ddb{1}> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf  9506   6426K    6802K  78643K     10865        0
            pcb    13      8K       8K  78643K        53        0
         rtable   113      4K       4K  78643K       253        0
         ifaddr    66     13K      13K  78643K        74        0
       counters    43     33K      34K  78643K        45        0
       ioctlops     0      0K       4K  78643K      1479        0
            iov     0      0K      16K  78643K        25        0
          mount     1      1K       1K  78643K         1        0
         vnodes  1217     77K      77K  78643K      1295        0
      UFS quota     1     32K      32K  78643K         1        0
      UFS mount     5     36K      36K  78643K         5        0
            shm     2      1K       5K  78643K         4        0
         VM map     2      1K       1K  78643K         2        0
            sem    12      0K       1K  78643K        17        0
        dirhash    12      2K       2K  78643K        12        0
           ACPI  1823    197K     290K  78643K     12980        0
      file desc     5     13K      25K  78643K       333        0
          sigio     0      0K       0K  78643K         3        0
           proc    60     63K      83K  78643K       466        0
        subproc    32      2K       2K  78643K        34        0
    NFS srvsock     1      0K       0K  78643K         1        0
     NFS daemon     1     16K      16K  78643K         1        0
    ip_moptions     0      0K       0K  78643K         7        0
       in_multi    46      2K       2K  78643K        69        0
    ether_multi     1      0K       0K  78643K         7        0
            mrt     0      0K       0K  78643K         2        0
    ISOFS mount     1     32K      32K  78643K         1        0
  MSDOSFS mount     1     16K      16K  78643K         1        0
           ttys    55    254K     254K  78643K        55        0
           exec     0      0K       1K  78643K       223        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   120     39K      40K  78643K      1989        0
       UVM aobj     4      2K       2K  78643K         6        0
        memdesc     1      4K       4K  78643K         1        0
    crypto data     1      1K       1K  78643K         1        0
    ip6_options     0      0K       0K  78643K        96        0
            NDP    10      0K       0K  78643K        16        0
           temp    85   3036K    3100K  78643K      9534        0
         kqueue     3      4K       8K  78643K        12        0
      SYN cache     2     16K      16K  78643K         2        0
ddb{1}> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
arp         64        7    0        0     1     0     1     1     0     8    0
plcache    128       20    0        0     1     0     1     1     0     8    0
rtpcb       80       35    0       33     1     0     1     1     0     8    0
rtentry    112       54    0        9     2     0     2     2     0     8    0
unpcb      120      601    0      589     1     0     1     1     0     8    0
syncache   264        6    0        6     2     2     0     1     0     8    0
tcpcb      544      177    0      173     1     0     1     1     0     8    0
ipq         40        2    0        2     1     1     0     1     0     8    0
ipqe        40        4    0        4     1     1     0     1     0     8    0
inpcb      280      380    0      373     3     2     1     2     0     8    0
nd6         48        9    0        4     1     0     1     1     0     8    0
ppxss      1128       1    0        1     1     1     0     1     0     8    0
pffrag     232        1    0        1     1     1     0     1     0   482    0
pffrnode    88        1    0        1     1     1     0     1     0     8    0
pffrent     40        4    0        4     2     2     0     1     0     8    0
pfosfp      40      846    0      423     5     0     5     5     0     8    0
pfosfpen   112     1428    0      714    21     0    21    21     0     8    0
pfstitem    24       32    0       16     1     0     1     1     0     8    0
pfstkey    112       32    0       16     1     0     1     1     0     8    0
pfstate    328       32    0       16     3     0     3     3     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      252    0       55    14     1    13    14     0     8    0
art_table   32      253    0       55     2     0     2     2     0     8    0
art_node    16       53    0       11     1     0     1     1     0     8    0
semupl     112        4    0        4     1     1     0     1     0     8    0
semapl     112       11    0        1     1     0     1     1     0     8    0
shmpl      112        4    0        2     1     0     1     1     0     8    0
dirhash    1024      17    0        0     3     0     3     3     0     8    0
dino2pl    256     2109    0      698    89     0    89    89     0     8    0
ffsino     272     2109    0      698    95     0    95    95     0     8    0
nchpl      144     3140    0     1519    62     1    61    61     0     8    0
uvmvnodes   72     2211    0        0    41     0    41    41     0     8    0
vnodes     208     2211    0        0   117     0   117   117     0     8    0
namei      1024    8920    0     8919     1     0     1     1     0     8    0
percpumem   16       33    0        1     1     0     1     1     0     8    0
vcpupl     1984       2    0        0     1     0     1     1     0     8    0
vmpool     560        2    0        0     1     0     1     1     0     8    0
scxspl     192     8221    0     8221     8     7     1     7     0     8    1
plimitpl   152       25    0       17     1     0     1     1     0     8    0
sigapl     424      549    0      517     4     0     4     4     0     8    0
futexpl     56     4913    0     4913     1     0     1     1     0     8    1
knotepl    112       69    0       50     1     0     1     1     0     8    0
kqueuepl   144       34    0       32     1     0     1     1     0     8    0
pipelkpl    48      115    0      105     1     0     1     1     0     8    0
pipepl     120      230    0      211     2     1     1     2     0     8    0
fdescpl    496      533    0      517     3     0     3     3     0     8    0
filepl     152     3405    0     3301     9     4     5     7     0     8    1
lockfpl    104       49    0       48     1     0     1     1     0     8    0
lockfspl    48       20    0       19     1     0     1     1     0     8    0
sessionpl  112       18    0        7     1     0     1     1     0     8    0
pgrppl      48       18    0        7     1     0     1     1     0     8    0
ucredpl     96      171    0      162     1     0     1     1     0     8    0
zombiepl   144      517    0      517     1     0     1     1     0     8    1
processpl  984      549    0      517     5     0     5     5     0     8    0
procpl     624     1232    0     1187     4     0     4     4     0     8    0
sosppl     128        2    0        2     1     1     0     1     0     8    0
sockpl     400     1016    0      995     6     3     3     5     0     8    0
mcl64k     65536      5    0        0     1     0     1     1     0     8    0
mcl12k     12288      2    0        0     1     0     1     1     0     8    0
mcl8k      8192       1    0        0     1     0     1     1     0     8    0
mcl4k      4096       4    0        0     1     0     1     1     0     8    0
mcl2k2     2112       1    0        0     1     0     1     1     0     8    0
mcl2k      2048     181    0        0    22     1    21    22     0     8    0
mtagpl      80       29    0        0     1     0     1     1     0     8    0
mbufpl     256      286    0        0    18     0    18    18     0     8    0
bufpl      280     4007    0      133   277     0   277   277     0     8    0
anonpl      16    55367    0    42082    56     2    54    55     0   124    0
amapchunkpl 152    2776    0     2634    13     5     8    13     0   158    0
amappl16   192     2318    0     1607    36     0    36    36     0     8    0
amappl15   184      119    0      115     1     0     1     1     0     8    0
amappl14   176       22    0       19     1     0     1     1     0     8    0
amappl13   168       26    0       25     1     0     1     1     0     8    0
amappl12   160      117    0      112     1     0     1     1     0     8    0
amappl11   152       60    0       45     1     0     1     1     0     8    0
amappl10   144       20    0       15     1     0     1     1     0     8    0
amappl9    136      583    0      579     1     0     1     1     0     8    0
amappl8    128      534    0      505     1     0     1     1     0     8    0
amappl7    120      118    0      106     1     0     1     1     0     8    0
amappl6    112       21    0       19     2     1     1     1     0     8    0
amappl5    104      430    0      413     1     0     1     1     0     8    0
amappl4     96      483    0      457     1     0     1     1     0     8    0
amappl3     88      103    0       97     1     0     1     1     0     8    0
amappl2     80     3426    0     3354     2     0     2     2     0     8    0
amappl1     72    21127    0    20675    23    13    10    18     0     8    0
amappl      80     1475    0     1426     2     0     2     2     0    84    0
dma4096    4096       1    0        1     1     1     0     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        5    0        2     1     0     1     1     0     8    0
uaddrrnd    24      535    0      517     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24      535    0      517     1     0     1     1     0     8    0
vmmpekpl   168     7857    0     7823     2     0     2     2     0     8    0
vmmpepl    168    71022    0    69144   106    23    83   101     0   357    0
vmsppl     368      534    0      517     2     0     2     2     0     8    0
pdppl      4096    1078    0     1036     6     0     6     6     0     8    0
pvpl        32   191767    0   175307   139     5   134   139     0   265    0
pmappl     232      534    0      517     2     0     2     2     0     8    0
extentpl    40       46    0       29     1     0     1     1     0     8    0
phpool     112      269    0        8     8     0     8     8     0     8    0
ddb{1}> machine ddbcpu 0
Stopped at      x86_ipi_db+0x1a:        addq    $0x8,%rsp
x86_ipi_db(ffffffff824b6ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:352
x86_ipi_handler() at x86_ipi_handler+0xc6 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23
__sanitizer_cov_trace_cmp4(9325a,9325b) at __sanitizer_cov_trace_cmp4+0x33 trace_cmp sys/dev/kcov.c:136 [inline]
__sanitizer_cov_trace_cmp4(9325a,9325b) at __sanitizer_cov_trace_cmp4+0x33 sys/dev/kcov.c:170
__mp_lock(ffffffff8268a5c0) at __mp_lock+0x139 __mp_lock_spin sys/kern/kern_lock.c:116 [inline]
__mp_lock(ffffffff8268a5c0) at __mp_lock+0x139 sys/kern/kern_lock.c:147
sys_futex(ffff800020ed8eb8,ffff800023fc5940,ffff800023fc5990) at sys_futex+0xf6 sys/kern/sys_futex.c:109
syscall(ffff800023fc5a10) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff800023fc5a10) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9fae58d1500, count: 7
ddb{0}> trace
x86_ipi_db(ffffffff824b6ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:352
x86_ipi_handler() at x86_ipi_handler+0xc6 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23
__sanitizer_cov_trace_cmp4(9325a,9325b) at __sanitizer_cov_trace_cmp4+0x33 trace_cmp sys/dev/kcov.c:136 [inline]
__sanitizer_cov_trace_cmp4(9325a,9325b) at __sanitizer_cov_trace_cmp4+0x33 sys/dev/kcov.c:170
__mp_lock(ffffffff8268a5c0) at __mp_lock+0x139 __mp_lock_spin sys/kern/kern_lock.c:116 [inline]
__mp_lock(ffffffff8268a5c0) at __mp_lock+0x139 sys/kern/kern_lock.c:147
sys_futex(ffff800020ed8eb8,ffff800023fc5940,ffff800023fc5990) at sys_futex+0xf6 sys/kern/sys_futex.c:109
syscall(ffff800023fc5a10) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff800023fc5a10) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9fae58d1500, count: -8
ddb{0}> machine ddbcpu 1
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff822454f2) at panic+0x15c sys/kern/subr_prf.c:207
vref(fffffd806506e4e8) at vref+0x7e sys/kern/vfs_subr.c:691
namei(ffff80002318af80) at namei+0x86b sys/kern/vfs_lookup.c:329
sys_chdir(ffff800020ed8768,ffff80002318b0b8,ffff80002318b100) at sys_chdir+0x76 change_dir sys/kern/vfs_syscalls.c:851 [inline]
sys_chdir(ffff800020ed8768,ffff80002318b0b8,ffff80002318b100) at sys_chdir+0x76 sys/kern/vfs_syscalls.c:797
syscall(ffff80002318b180) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff80002318b180) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9fbb317bb60, count: 8
ddb{1}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff822454f2) at panic+0x15c sys/kern/subr_prf.c:207
vref(fffffd806506e4e8) at vref+0x7e sys/kern/vfs_subr.c:691
namei(ffff80002318af80) at namei+0x86b sys/kern/vfs_lookup.c:329
sys_chdir(ffff800020ed8768,ffff80002318b0b8,ffff80002318b100) at sys_chdir+0x76 change_dir sys/kern/vfs_syscalls.c:851 [inline]
sys_chdir(ffff800020ed8768,ffff80002318b0b8,ffff80002318b100) at sys_chdir+0x76 sys/kern/vfs_syscalls.c:797
syscall(ffff80002318b180) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff80002318b180) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9fbb317bb60, count: -7

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/05/10 03:00 openbsd bb2235eb78e4 8742a2b9 .config console log report ci-openbsd-multicore
2020/05/06 18:45 openbsd 7237aa572037 4618eb2d .config console log report ci-openbsd-multicore
* Struck through repros no longer work on HEAD.