syzbot


panic: vrele: v_writecount != 0 (2)

Status: fixed on 2021/02/04 23:26
Reported-by: syzbot+b0e18235e96adf81883d@syzkaller.appspotmail.com
Fix commit: df61468f8652 Revert previous commit. The vnode returned by ptm_vn_open() is open and can not simply be vrele()-ed on error. The code currently depends on closef() to do the cleanup.
First crash: 661d, last: 661d
similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
openbsd panic: vrele: v_writecount != 0 C 51 1210d 1215d 3/3 fixed on 2019/08/05 23:05

Sample crash report:
panic: vrele: v_writecount != 0
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*251929  86380      0         0x2  0x4000000    0  syz-executor1255
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff8243627a) at panic+0x15e sys/kern/subr_prf.c:218
vrele(fffffd807aa48408) at vrele+0x187 sys/kern/vfs_subr.c:803
ptmioctl(5100,40287401,ffff8000216cbc00,3,ffff800021697270) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225
VOP_IOCTL(fffffd806e6c6050,40287401,ffff8000216cbc00,3,fffffd807f7b7d80,ffff800021697270) at VOP_IOCTL+0x91 sys/kern/vfs_vops.c:297
vn_ioctl(fffffd806e6b5170,40287401,ffff8000216cbc00,ffff800021697270) at vn_ioctl+0xb5 sys/kern/vfs_vnops.c:531
sys_ioctl(ffff800021697270,ffff8000216cbd10,ffff8000216cbd60) at sys_ioctl+0x4ac
syscall(ffff8000216cbde0) at syscall+0x507 sys/arch/amd64/amd64/trap.c:590
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xd8d74e49d10, count: 6
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
vrele: v_writecount != 0
ddb> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff8243627a) at panic+0x15e sys/kern/subr_prf.c:218
vrele(fffffd807aa48408) at vrele+0x187 sys/kern/vfs_subr.c:803
ptmioctl(5100,40287401,ffff8000216cbc00,3,ffff800021697270) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225
VOP_IOCTL(fffffd806e6c6050,40287401,ffff8000216cbc00,3,fffffd807f7b7d80,ffff800021697270) at VOP_IOCTL+0x91 sys/kern/vfs_vops.c:297
vn_ioctl(fffffd806e6b5170,40287401,ffff8000216cbc00,ffff800021697270) at vn_ioctl+0xb5 sys/kern/vfs_vnops.c:531
sys_ioctl(ffff800021697270,ffff8000216cbd10,ffff8000216cbd60) at sys_ioctl+0x4ac
syscall(ffff8000216cbde0) at syscall+0x507 sys/arch/amd64/amd64/trap.c:590
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xd8d74e49d10, count: -9
ddb> show registers
rdi                                0
rsi                              0x1
rbp               0xffff8000216cb640
rbx               0xffff8000216cb650
rdx                             0x8b
rcx                              0x2
rax                              0x1
r8                0xffffffff820e50f5    kprintf+0x155
r9                               0x1
r10               0x72d6a74aa10202f7
r11                0x8e7180593447e8e
r12                     0x3000000008
r13               0xffff8000216cb6f0
r14                            0x100
r15                              0x1
rip               0xffffffff81ab85c8    db_enter+0x18
cs                               0x8
rflags                         0x246
rsp               0xffff8000216cb630
ss                              0x10
db_enter+0x18:  addq    $0x8,%rsp
ddb> show proc
PROC (syz-executor1255) pid=251929 stat=onproc
    flags process=2<EXEC,8ORPHAN> proc=4000000<THREAD>
    pri=32, usrpri=50, nice=20
    forw=0xffffffffffffffff, list=0xffff800021696a90,0xffffffff827ebf10
    process=0xffff800021698808 user=0xffff8000216c6000, vmspace=0xfffffd807effc000
    estcpu=0, cpticks=2, pctcpu=0.0
    user=0, sys=2, intr=0
ddb> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 86380  461900  23501      0  2         0x2                syz-executor1255
*86380  251929  23501      0  7   0x4000002                syz-executor1255
 23501  388786  77213      0  3    0x10008a  sigsusp       ksh
 77213  384441  23694      0  3        0x92  select        sshd
 24610  307496      1      0  3    0x100083  ttyin         getty
 23694  496809      1      0  3        0x80  select        sshd
 63799  215322    387     73  3    0x100090  kqread        syslogd
   387  484722      1      0  3    0x100082  netio         syslogd
 41355  196815      1     77  3    0x100090  poll          dhclient
 45921  328280      1      0  3        0x80  poll          dhclient
 55028  124421      0      0  3     0x14200  bored         smr
 79955  338904      0      0  2     0x14200                zerothread
 52476  328560      0      0  3     0x14200  aiodoned      aiodoned
 16828  118230      0      0  3     0x14200  syncer        update
 89495  101359      0      0  3     0x14200  cleaner       cleaner
 49386  447446      0      0  3     0x14200  reaper        reaper
 65670  255095      0      0  3     0x14200  pgdaemon      pagedaemon
 37430  344970      0      0  3     0x14200  bored         crynlk
 86617  451998      0      0  3     0x14200  bored         crypto
  3713  365716      0      0  3     0x14200  bored         viomb
 78049  161911      0      0  3  0x40014200  acpi0         acpi0
 25686  445512      0      0  3     0x14200  bored         softnet
 78058   10955      0      0  3     0x14200  bored         systqmp
 29497  141258      0      0  3     0x14200  bored         systq
 55395   65817      0      0  3  0x40014200  bored         softclock
 96366  438557      0      0  3  0x40014200                idle0
     1  246423      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  9459   6338K    6338K  78643K     10549        0
            pcb    13      8K       8K  78643K        13        0
         rtable    61      2K       2K  78643K       117        0
         ifaddr    24      7K       7K  78643K        24        0
       counters    19     16K      16K  78643K        19        0
       ioctlops     0      0K       2K  78643K        13        0
          mount     1      1K       1K  78643K         1        0
         vnodes  1182     74K      74K  78643K      1187        0
      UFS quota     1     32K      32K  78643K         1        0
      UFS mount     5     36K      36K  78643K         5        0
            shm     2      1K       1K  78643K         2        0
         VM map     2      0K       0K  78643K         2        0
            sem     2      0K       0K  78643K         2        0
        dirhash    12      2K       2K  78643K        12        0
           ACPI  1697    195K     286K  78643K     12598        0
      file desc     1      0K       0K  78643K         1        0
           proc    47     38K      46K  78643K       284        0
    NFS srvsock     1      0K       0K  78643K         1        0
     NFS daemon     1     16K      16K  78643K         1        0
       in_multi    11      0K       0K  78643K        11        0
    ether_multi     1      0K       0K  78643K         1        0
    ISOFS mount     1     32K      32K  78643K         1        0
  MSDOSFS mount     1     16K      16K  78643K         1        0
           ttys    31    148K     148K  78643K        31        0
           exec     0      0K       2K  78643K       261        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    33      1K       2K  78643K       512        0
       UVM aobj     3      2K       2K  78643K         3        0
        memdesc     1      4K       4K  78643K         1        0
    crypto data     1      1K       1K  78643K         1        0
            NDP     3      0K       0K  78643K         3        0
           temp    18   3961K    4025K  78643K      1442        0
         kqueue     2      2K       2K  78643K         2        0
      SYN cache     2     16K      16K  78643K         2        0
ddb> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
arp         64        2    0        0     1     0     1     1     0     8    0
rtpcb      120       15    0       13     1     0     1     1     0     8    0
rtentry    112       23    0        1     1     0     1     1     0     8    0
unpcb      120       27    0       19     1     0     1     1     0     8    0
syncache   296        5    0        5     2     1     1     1     0     8    1
tcpcb      736        8    0        5     1     0     1     1     0     8    0
inpcb      304       22    0       16     1     0     1     1     0     8    0
art_heap8  4096       1    0        0     1     0     1     1     0     8    0
art_heap4  256       96    0        0     6     0     6     6     0     8    0
art_table   32       97    0        0     1     0     1     1     0     8    0
art_node    16       22    0        2     1     0     1     1     0     8    0
dirhash    1024      17    0        0     3     0     3     3     0     8    0
dino2pl    256     1389    0       15    86     0    86    86     0     8    0
ffsino     240     1389    0       15    81     0    81    81     0     8    0
nchpl      144     1563    0       31    57     0    57    57     0     8    0
uvmvnodes   72     1398    0        0    26     0    26    26     0     8    0
vnodes     224     1398    0        0    83     0    83    83     0     8    0
namei      1024    3497    0     3497     2     1     1     1     0     8    1
scxspl     216     3434    0     3434    10     9     1     8     0     8    1
plimitpl   152       15    0        9     1     0     1     1     0     8    0
sigapl     424      192    0      166     4     0     4     4     0     8    0
futexpl     56        3    0        3     1     0     1     1     0     8    1
knotepl    112        5    0        0     1     0     1     1     0     8    0
kqueuepl   168        1    0        0     1     0     1     1     0     8    0
pipepl     304       57    0       53     2     1     1     1     0     8    0
fdescpl    432      177    0      166     2     0     2     2     0     8    0
filepl     120      827    0      781     2     0     2     2     0     8    0
lockfpl    104        5    0        4     1     0     1     1     0     8    0
lockfspl    48        3    0        2     1     0     1     1     0     8    0
sessionpl  144       17    0        9     1     0     1     1     0     8    0
pgrppl      48       17    0        9     1     0     1     1     0     8    0
ucredpl     96       63    0       56     1     0     1     1     0     8    0
zombiepl   144      166    0      166     2     1     1     1     0     8    1
processpl  1016     192    0      166     4     0     4     4     0     8    0
procpl     672      193    0      166     3     0     3     3     0     8    0
sockpl     432       64    0       48     2     0     2     2     0     8    0
mcl4k      4096      10    0       10     2     1     1     1     0     8    1
mcl2k      2048    6263    0     6223    10     3     7     9     0     8    1
mtagpl      96        2    0        2     1     1     0     1     0     8    0
mbufpl     256     7903    0     7850     7     2     5     6     0     8    1
bufpl      280     1914    0      101   130     0   130   130     0     8    0
anonpl      24    18263    0    17106    11     3     8    10     0   188    1
amapchunkpl 152     470    0      433     3     1     2     3     0   158    0
amappl16   200       67    0       62     1     0     1     1     0     8    0
amappl15   192        1    0        0     1     0     1     1     0     8    0
amappl14   184       22    0       19     1     0     1     1     0     8    0
amappl13   176       12    0       11     2     1     1     1     0     8    0
amappl12   168        8    0        8     2     1     1     1     0     8    1
amappl11   160       47    0       38     1     0     1     1     0     8    0
amappl10   152       13    0       11     1     0     1     1     0     8    0
amappl9    144      220    0      220     2     1     1     1     0     8    1
amappl8    136       59    0       57     1     0     1     1     0     8    0
amappl7    128      183    0      182     1     0     1     1     0     8    0
amappl6    120       50    0       44     1     0     1     1     0     8    0
amappl5    112      343    0      329     1     0     1     1     0     8    0
amappl4    104      241    0      219     1     0     1     1     0     8    0
amappl3     96       92    0       85     1     0     1     1     0     8    0
amappl2     88      759    0      706     2     0     2     2     0     8    0
amappl1     80    12672    0    12271    18     7    11    18     0     8    0
amappl      88      349    0      330     1     0     1     1     0    92    0
dma4096    4096       1    0        1     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      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        2    0        0     1     0     1     1     0     8    0
uaddrrnd    24      177    0      166     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24      177    0      166     1     0     1     1     0     8    0
vmmpekpl   168     5290    0     5275     1     0     1     1     0     8    0
vmmpepl    168    26397    0    25610    53    17    36    48     0   357    1
vmsppl     272      176    0      166     1     0     1     1     0     8    0
rwobjpl     24     6985    0     6466     6     2     4     6     0     8    0
pdppl      4096     360    0      332    44    16    28    34     0     8    0
pvpl        32    72525    0    69716    33     6    27    27     0   265    2
pmappl     200      176    0      166     1     0     1     1     0     8    0
extentpl    40       58    0       40     1     0     1     1     0     8    0
phpool     112      251    0       25     7     0     7     7     0     8    0
ddb> machine ddbcpu 0
No such command
ddb> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff8243627a) at panic+0x15e sys/kern/subr_prf.c:218
vrele(fffffd807aa48408) at vrele+0x187 sys/kern/vfs_subr.c:803
ptmioctl(5100,40287401,ffff8000216cbc00,3,ffff800021697270) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225
VOP_IOCTL(fffffd806e6c6050,40287401,ffff8000216cbc00,3,fffffd807f7b7d80,ffff800021697270) at VOP_IOCTL+0x91 sys/kern/vfs_vops.c:297
vn_ioctl(fffffd806e6b5170,40287401,ffff8000216cbc00,ffff800021697270) at vn_ioctl+0xb5 sys/kern/vfs_vnops.c:531
sys_ioctl(ffff800021697270,ffff8000216cbd10,ffff8000216cbd60) at sys_ioctl+0x4ac
syscall(ffff8000216cbde0) at syscall+0x507 sys/arch/amd64/amd64/trap.c:590
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xd8d74e49d10, count: -9
ddb> machine ddbcpu 1
No such command
ddb> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff8243627a) at panic+0x15e sys/kern/subr_prf.c:218
vrele(fffffd807aa48408) at vrele+0x187 sys/kern/vfs_subr.c:803
ptmioctl(5100,40287401,ffff8000216cbc00,3,ffff800021697270) at ptmioctl+0x5b9 sys/kern/tty_pty.c:1225
VOP_IOCTL(fffffd806e6c6050,40287401,ffff8000216cbc00,3,fffffd807f7b7d80,ffff800021697270) at VOP_IOCTL+0x91 sys/kern/vfs_vops.c:297
vn_ioctl(fffffd806e6b5170,40287401,ffff8000216cbc00,ffff800021697270) at vn_ioctl+0xb5 sys/kern/vfs_vnops.c:531
sys_ioctl(ffff800021697270,ffff8000216cbd10,ffff8000216cbd60) at sys_ioctl+0x4ac
syscall(ffff8000216cbde0) at syscall+0x507 sys/arch/amd64/amd64/trap.c:590
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xd8d74e49d10, count: -9
ddb> 

Crashes (1955):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-openbsd-main 2021/02/04 14:16 openbsd a1753de66958 42b90a7c .config log report syz C panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 13:53 openbsd a1753de66958 42b90a7c .config log report syz C panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:51 openbsd a1753de66958 42b90a7c .config log report syz C panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 22:33 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 20:16 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 17:57 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:58 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:53 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:49 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:44 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:40 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:39 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 13:37 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:35 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:33 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:33 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:32 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:29 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:28 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 13:26 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:24 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:23 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:21 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:19 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:18 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:16 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:14 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 13:13 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:11 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:10 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 13:08 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 13:06 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 13:05 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 13:03 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 13:01 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 13:00 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 12:58 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 12:56 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 12:55 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 12:53 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 12:51 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 12:50 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-main 2021/02/04 12:50 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 12:48 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 12:47 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 12:45 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-setuid 2021/02/04 12:43 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 12:42 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
ci-openbsd-multicore 2021/02/04 11:01 openbsd a1753de66958 42b90a7c .config log report panic: vrele: v_writecount != 0
* Struck through repros no longer work on HEAD.