syzbot


assert "curproc->p_kd == NULL" failed in kcov.c

Status: fixed on 2020/08/15 01:06
Reported-by: syzbot+1252e696865efc29b767@syzkaller.appspotmail.com
Fix commit: 2fa3abdda1a4 When detaching common remote coverage, do not clear any fields. Instead, let kr_free() do the work. Otherwise a thread currently inside a remote section could end up not decrementing the number of ongoing sections while exiting the same remote section.
First crash: 1572d, last: 1571d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
openbsd assert "curproc->p_kd == NULL" failed in kcov.c (2) 1 1566d 1566d 3/3 fixed on 2020/09/01 02:15

Sample crash report:
panic: kernel diagnostic assertion "curproc->p_kd == NULL" failed: file "/syzkaller/managers/multicore/kernel/sys/dev/kcov.c", line 519
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
 374416  74252      0        0x12       0x40    0K sshd
*102222  78585      0     0x14000      0x200    1  softnet
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff823bf498) at panic+0x15e sys/kern/subr_prf.c:218
__assert(ffffffff8242d3f9,ffffffff8242c702,207,ffffffff823d1f6e) at __assert+0x2b sys/kern/subr_prf.c:162
kcov_remote_enter(0,ffff800020eb4bd8) at kcov_remote_enter+0x155 sys/dev/kcov.c:519
taskq_thread(ffff80000002c000) at taskq_thread+0xd9 sys/kern/kern_task.c:447
end trace frame: 0x0, count: 10
https://www.openbsd.org/ddb.html describes the minimum info required in bug
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ddb{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
kernel diagnostic assertion "curproc->p_kd == NULL" failed: file "/syzkaller/managers/multicore/kernel/sys/dev/kcov.c", line 519
ddb{1}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff823bf498) at panic+0x15e sys/kern/subr_prf.c:218
__assert(ffffffff8242d3f9,ffffffff8242c702,207,ffffffff823d1f6e) at __assert+0x2b sys/kern/subr_prf.c:162
kcov_remote_enter(0,ffff800020eb4bd8) at kcov_remote_enter+0x155 sys/dev/kcov.c:519
taskq_thread(ffff80000002c000) at taskq_thread+0xd9 sys/kern/kern_task.c:447
end trace frame: 0x0, count: -5
ddb{1}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff800020db94a0
rbx               0xffff800020db94b0
rdx                             0x8b
rcx                              0x2
rax                              0x1
r8                0xffff800020db9460
r9                0xffffffff8140d116    kprintf+0x146
r10                              0x1
r11               0x9d8807188bb17d8b
r12                     0x3000000008
r13               0xffff800020db9550
r14                            0x100
r15                              0x1
rip               0xffffffff81f4faf8    db_enter+0x18
cs                               0x8
rflags                         0x246
rsp               0xffff800020db9490
ss                              0x10
db_enter+0x18:  addq    $0x8,%rsp
ddb{1}> show proc
PROC (softnet) pid=102222 stat=onproc
    flags process=14000<NOZOMBIE,SYSTEM> proc=200<SYSTEM>
    pri=32, usrpri=50, nice=20
    forw=0xffffffffffffffff, list=0xffff800020d984f0,0xffff800020d98c68
    process=0xffff800020d9abd0 user=0xffff800020db4000, vmspace=0xffffffff828deaf8
    estcpu=0, cpticks=2, pctcpu=0.1
    user=0, sys=2, intr=0
ddb{1}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 30539  139308  62850      0  2         0x2                syz-executor.1
 58707  422593      1      0  3    0x100083  ttyin         getty
 84591  192581      0      0  3     0x14200  acct          acct
 73856  135794      0      0  3     0x14200  bored         sosplice
 62850  301227  21109      0  3        0x82  thrsleep      syz-fuzzer
 62850  440372  21109      0  2   0x4000482                syz-fuzzer
 62850  237138  21109      0  3   0x4000082  thrsleep      syz-fuzzer
 62850   89651  21109      0  2   0x4000482                syz-fuzzer
 62850   14559  21109      0  3   0x4000082  thrsleep      syz-fuzzer
 62850   67083  21109      0  3   0x4000082  thrsleep      syz-fuzzer
 62850   57960  21109      0  3   0x4000082  thrsleep      syz-fuzzer
 62850  156545  21109      0  2   0x4000002                syz-fuzzer
 62850  404775  21109      0  3   0x4000082  thrsleep      syz-fuzzer
 21109  395483  74252      0  3    0x10008a  pause         ksh
 74252  374416  42622      0  7        0x52                sshd
 42622   20041      1      0  3        0x80  select        sshd
 38321  507911  40125     74  3    0x100092  bpf           pflogd
 40125  151826      1      0  3        0x80  netio         pflogd
 49380   77419  98003     73  3    0x100090  kqread        syslogd
 98003  129920      1      0  3    0x100082  netio         syslogd
 85777   65969      1     77  3    0x100090  poll          dhclient
 45352  463009      1      0  3        0x80  poll          dhclient
 83347    8955      0      0  3     0x14200  bored         smr
 90871  289910      0      0  3     0x14200  pgzero        zerothread
 10562  136675      0      0  3     0x14200  aiodoned      aiodoned
 71153  247567      0      0  3     0x14200  syncer        update
 48965  479310      0      0  3     0x14200  cleaner       cleaner
 61739   52070      0      0  3     0x14200  reaper        reaper
 96199  466941      0      0  3     0x14200  pgdaemon      pagedaemon
 90487  286673      0      0  3     0x14200  bored         crynlk
 77238  393031      0      0  3     0x14200  bored         crypto
 69426  269485      0      0  3  0x40014200  acpi0         acpi0
   347  371264      0      0  3  0x40014200                idle1
*78585  102222      0      0  7     0x14200                softnet
  7967  346968      0      0  3     0x14200  bored         systqmp
 51961  264473      0      0  3     0x14200  bored         systq
 68081  272363      0      0  3  0x40014200  bored         softclock
 28254  143909      0      0  3  0x40014200                idle0
     1  241409      0      0  3        0x82  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb{1}> show all locks
CPU 1:
exclusive mutex /syzkaller/managers/multicore/kernel/sys/dev/kcov.c:92 r = 0 (0xffffffff82744e30)
#0  witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0  witness_lock+0x4b0 sys/kern/subr_witness.c:1164
#1  mtx_enter_try+0x100
#2  mtx_enter+0x4b sys/kern/kern_lock.c:266
#3  kcov_remote_enter+0x62 kr_lookup sys/dev/kcov.c:676 [inline]
#3  kcov_remote_enter+0x62 sys/dev/kcov.c:513
#4  taskq_thread+0xd9 sys/kern/kern_task.c:447
#5  proc_trampoline+0x1c
Process 30539 (syz-executor.1) thread 0xffff800020eb33d8 (139308)
exclusive rrwlock inode r = 0 (0xfffffd806e5bd1a8)
#0  witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0  witness_lock+0x4b0 sys/kern/subr_witness.c:1164
#1  rw_enter+0x446 sys/kern/kern_rwlock.c:311
#2  rrw_enter+0x88 sys/kern/kern_rwlock.c:462
#3  ufs_ihashins+0x45 sys/ufs/ufs/ufs_ihash.c:140
#4  ffs_vget+0x135 sys/ufs/ffs/ffs_vfsops.c:1350
#5  ffs_inode_alloc+0x1e1 sys/ufs/ffs/ffs_alloc.c:394
#6  ufs_mkdir+0xf4 sys/ufs/ufs/ufs_vnops.c:1162
#7  VOP_MKDIR+0xc6 sys/kern/vfs_vops.c:450
#8  domkdirat+0x121 sys/kern/vfs_syscalls.c:3051
#9  syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#9  syscall+0x4a1 sys/arch/amd64/amd64/trap.c:570
#10 Xsyscall+0x128
exclusive rrwlock inode r = 0 (0xfffffd8066ca82c0)
#0  witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0  witness_lock+0x4b0 sys/kern/subr_witness.c:1164
#1  rw_enter+0x446 sys/kern/kern_rwlock.c:311
#2  rrw_enter+0x88 sys/kern/kern_rwlock.c:462
#3  VOP_LOCK+0x4b sys/kern/vfs_vops.c:603
#4  vn_lock+0x6c sys/kern/vfs_vnops.c:575
#5  vfs_lookup+0xe6 sys/kern/vfs_lookup.c:419
#6  namei+0x5f7 sys/kern/vfs_lookup.c:249
#7  domkdirat+0x75 sys/kern/vfs_syscalls.c:3036
#8  syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#8  syscall+0x4a1 sys/arch/amd64/amd64/trap.c:570
#9  Xsyscall+0x128
Process 74252 (sshd) thread 0xffff8000fffff648 (374416)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff82896a28)
#0  witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0  witness_lock+0x4b0 sys/kern/subr_witness.c:1164
#1  __mp_acquire_count+0x4c sys/kern/kern_lock.c:227
#2  mi_switch+0x390 sys/kern/sched_bsd.c:435
#3  sleep_finish+0x111 sys/kern/kern_synch.c:418
#4  rw_enter+0x3cf
#5  solock+0x5a sys/kern/uipc_socket2.c:282
#6  soo_poll+0x3d sys/kern/sys_socket.c:161
#7  selscan+0x14d sys/kern/sys_generic.c:722
#8  dopselect+0x8b7 sys/kern/sys_generic.c:643
#9  sys_select+0x8b sys/kern/sys_generic.c:542
#10 syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
#10 syscall+0x4a1 sys/arch/amd64/amd64/trap.c:570
#11 Xsyscall+0x128
Process 78585 (softnet) thread 0xffff800020d989e0 (102222)
shared rwlock softnet r = 0 (0xffff80000002c070)
#0  witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0  witness_lock+0x4b0 sys/kern/subr_witness.c:1164
#1  taskq_thread+0xcb sys/kern/kern_task.c:445
#2  proc_trampoline+0x1c
exclusive mutex /syzkaller/managers/multicore/kernel/sys/dev/kcov.c:92 r = 0 (0xffffffff82744e30)
#0  witness_lock+0x4b0 stacktrace_save sys/sys/stacktrace.h:36 [inline]
#0  witness_lock+0x4b0 sys/kern/subr_witness.c:1164
#1  mtx_enter_try+0x100
#2  mtx_enter+0x4b sys/kern/kern_lock.c:266
#3  kcov_remote_enter+0x62 kr_lookup sys/dev/kcov.c:676 [inline]
#3  kcov_remote_enter+0x62 sys/dev/kcov.c:513
#4  taskq_thread+0xd9 sys/kern/kern_task.c:447
#5  proc_trampoline+0x1c
ddb{1}> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf  9547   6441K    7785K  78643K     21188        0
            pcb    13      8K       8K  78643K       503        0
         rtable    77     11K      12K  78643K      1346        0
         ifaddr    84     16K      17K  78643K       495        0
       counters    43     33K      34K  78643K       207        0
       ioctlops     0      0K       4K  78643K      1911        0
            iov     0      0K      24K  78643K       493        0
          mount     1      1K       1K  78643K         1        0
         vnodes  1232     77K      78K  78643K      4944        0
      UFS quota     1     32K      32K  78643K         1        0
      UFS mount     5     36K      36K  78643K         5        0
            shm     2      1K       9K  78643K        52        0
         VM map     2      1K       1K  78643K         2        0
            sem    12      0K       1K  78643K       888        0
        dirhash    12      2K       2K  78643K        12        0
           ACPI  1824    197K     290K  78643K     13058        0
      file desc     4      9K      25K  78643K      9034        0
          sigio     0      0K       0K  78643K        34        0
           proc    65     63K      95K  78643K      1069        0
        subproc    32      2K       2K  78643K       119        0
    NFS srvsock     1      0K       0K  78643K         1        0
     NFS daemon     1     16K      16K  78643K         1        0
    ip_moptions     0      0K       0K  78643K       630        0
       in_multi    22      1K       2K  78643K       412        0
    ether_multi     1      0K       0K  78643K        71        0
            mrt     0      0K       0K  78643K        69        0
    ISOFS mount     1     32K      32K  78643K         1        0
  MSDOSFS mount     1     16K      16K  78643K         1        0
           ttys    73    334K     334K  78643K        73        0
           exec     0      0K       2K  78643K       829        0
     pfkey data     0      0K       1K  78643K         5        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   250    291K     291K  78643K     21796        0
       UVM aobj    69      5K       5K  78643K        82        0
        memdesc     1      4K       4K  78643K         1        0
    crypto data     1      1K       1K  78643K         1        0
    ip6_options     0      0K       0K  78643K       400        0
            NDP    16      0K       0K  78643K       124        0
           temp   149   3967K    4039K  78643K     50139        0
         kqueue     3      4K      18K  78643K       381        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       22    0       18     1     0     1     1     0     8    0
plcache    128       20    0        0     1     0     1     1     0     8    0
rtpcb       96      313    0      311     1     0     1     1     0     8    0
rtentry    112      153    0      128     2     0     2     2     0     8    0
unpcb      120     2059    0     2003     3     1     2     3     0     8    0
syncache   272       78    0       78    10    10     0     1     0     8    0
tcpqe       32       27    0       27     4     4     0     1     0     8    0
tcpcb      592     1571    0     1567    21    19     2     5     0     8    1
inpcb      296     4484    0     4477    12    10     2     3     0     8    1
rttmr       72       33    0       33     4     3     1     1     0     8    1
nd6         48       32    0       29     1     0     1     1     0     8    0
pkpcb       40       37    0       37     5     5     0     1     0     8    0
kcovpl      48        7    0        5     1     0     1     1     0     8    0
ppxss      1136      43    0       43     6     5     1     1     0     8    1
pffrag     232       27    0       27     3     3     0     1     0   482    0
pffrnode    88       27    0       27     3     3     0     1     0     8    0
pffrent     40      612    0      612     3     3     0     1     0     8    0
pfosfp      40      847    0      423     5     0     5     5     0     8    0
pfosfpen   112     1429    0      714    21     0    21    21     0     8    0
pfrktable  1344      42    0       42     3     3     0     1     0     8    0
pftag       88        1    0        0     1     0     1     1     0     8    0
pfqueue    264        8    0        8     1     1     0     1     0     8    0
pfstitem    24       49    0       47     1     0     1     1     0     8    0
pfstkey    112       49    0       47     2     1     1     2     0     8    0
pfstate    328       49    0       47     4     3     1     4     0     8    0
pfrule     1360      65    0       64     2     1     1     2     0     8    0
art_heap8  4096       1    0        0     1     0     1     1     0     8    0
art_heap4  256      419    0      282    12     3     9    12     0     8    0
art_table   32      420    0      282     2     0     2     2     0     8    0
art_node    16      152    0      132     1     0     1     1     0     8    0
sysvmsgpl   40       44    0       21     2     1     1     1     0     8    0
semapl     112      886    0      876     1     0     1     1     0     8    0
shmpl      112       79    0       13     2     0     2     2     0     8    0
dirhash    1024      17    0        0     3     0     3     3     0     8    0
dino2pl    256    13556    0    12136    92     2    90    90     0     8    0
ffsino     272    13556    0    12136    96     0    96    96     0     8    0
nchpl      144    24684    0    23093    60     0    60    60     0     8    0
uvmvnodes   72     5926    0        0   108     0   108   108     0     8    0
vnodes     208     5926    0        0   312     0   312   312     0     8    0
namei      1024   61893    0    61892     4     3     1     1     0     8    0
percpumem   16      114    0       82     1     0     1     1     0     8    0
vcpupl     1984      19    0        0     3     0     3     3     0     8    0
vmpool     560       19    0        0     2     0     2     2     0     8    0
pfiaddrpl  120       14    0       14     3     3     0     1     0     8    0
scsiplug    72        9    0        9     2     1     1     1     0     8    1
scxspl     200    73056    0    73056    18    17     1     7     0     8    1
plimitpl   152      409    0      401     1     0     1     1     0     8    0
sigapl     424     9238    0     9206     4     0     4     4     0     8    0
futexpl     56    69241    0    69241     4     3     1     1     0     8    1
knotepl    112      546    0      526     1     0     1     1     0     8    0
kqueuepl   152     4219    0     4216     1     0     1     1     0     8    0
pipepl     304      538    0      527    16    14     2     2     0     8    1
fdescpl    496     9221    0     9206     3     0     3     3     0     8    0
filepl     152    33144    0    33042     7     2     5     6     0     8    1
lockfpl    104     1002    0     1001     1     0     1     1     0     8    0
lockfspl    48      411    0      410     1     0     1     1     0     8    0
sessionpl  120       24    0       13     1     0     1     1     0     8    0
pgrppl      48       42    0       31     1     0     1     1     0     8    0
ucredpl     96     4695    0     4683     1     0     1     1     0     8    0
zombiepl   144     9207    0     9206     2     1     1     1     0     8    0
processpl  1008    9238    0     9206     5     0     5     5     0     8    0
procpl     632    20502    0    20462    13     8     5     5     0     8    1
srpgc       72        2    0        2     1     1     0     1     0     8    0
sosppl     144      117    0      117     8     7     1     1     0     8    1
sockpl     400     6908    0     6839    14     6     8    10     0     8    0
mcl64k     65536     20    0        0     3     0     3     3     0     8    0
mcl16k     16384     10    0        0     2     0     2     2     0     8    0
mcl12k     12288     25    0        0     2     0     2     2     0     8    0
mcl9k      9216      16    0        0     2     0     2     2     0     8    0
mcl8k      8192      20    0        0     3     1     2     3     0     8    0
mcl4k      4096      26    0        0     4     1     3     3     0     8    0
mcl2k2     2112       7    0        0     1     0     1     1     0     8    0
mcl2k      2048     273    0        0    15     0    15    15     0     8    0
mtagpl      96      386    0        0     8     0     8     8     0     8    0
mbufpl     256      981    0        0    58     0    58    58     0     8    0
bufpl      280    17551    0    11295   447     0   447   447     0     8    0
anonpl      16   713507    0   705408    99    64    35    54     0   124    1
amapchunkpl 152   38964    0    38786    46    38     8    19     0   158    0
amappl16   192    31426    0    31096    67    49    18    34     0     8    1
amappl15   184        3    0        1     1     0     1     1     0     8    0
amappl14   176     3754    0     3749     1     0     1     1     0     8    0
amappl13   168      103    0      101     1     0     1     1     0     8    0
amappl12   160      278    0      273     1     0     1     1     0     8    0
amappl11   152       67    0       52     1     0     1     1     0     8    0
amappl10   144     4958    0     4953     1     0     1     1     0     8    0
amappl9    136      317    0      317     1     1     0     1     0     8    0
amappl8    128      410    0      278     5     0     5     5     0     8    0
amappl7    120     5255    0     5246     1     0     1     1     0     8    0
amappl6    112      155    0      133     1     0     1     1     0     8    0
amappl5    104     9442    0     9428     1     0     1     1     0     8    0
amappl4     96      395    0      364     1     0     1     1     0     8    0
amappl3     88     4007    0     3999     1     0     1     1     0     8    0
amappl2     80    64618    0    64542     3     1     2     3     0     8    0
amappl1     72   243217    0   242782    25    15    10    19     0     8    0
amappl      80    20907    0    20836     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       81    0       13     2     0     2     2     0     8    0
uaddrrnd    24     9240    0     9206     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24     9240    0     9206     1     0     1     1     0     8    0
vmmpekpl   168    39945    0    39898     3     0     3     3     0     8    0
vmmpepl    168  1118602    0  1117045   149    69    80    90     0   357    2
vmsppl     368     9239    0     9206     5     1     4     4     0     8    0
pdppl      4096   18487    0    18431    10     2     8     8     0     8    0
pvpl        32  3023594    0  3012586   285   171   114   151     0   265   21
pmappl     232     9239    0     9206     4     1     3     3     0     8    0
extentpl    40       53    0       36     1     0     1     1     0     8    0
phpool     112      336    0       32     9     0     9     9     0     8    0
ddb{1}> machine ddbcpu 0
Stopped at      x86_ipi_db+0x1a:        addq    $0x8,%rsp
x86_ipi_db(ffffffff826d7ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:352
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23
__sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc
pipe_poll(fffffd806fc0d720,1,ffff8000fffff648) at pipe_poll+0x17c sys/kern/sys_pipe.c:738
selscan(ffff8000fffff648,ffff800020e14810,ffff800020e1481c,c,4,ffff800020e149f0) at selscan+0x14d sys/kern/sys_generic.c:722
dopselect(ffff8000fffff648,c,4317bb3ef20,432490e29e0,0,0) at dopselect+0x8b7 sys/kern/sys_generic.c:643
sys_select(ffff8000fffff648,ffff800020e149a0,ffff800020e149f0) at sys_select+0x8b sys/kern/sys_generic.c:542
syscall(ffff800020e14a70) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff800020e14a70) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:570
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7f7ffffd4ab0, count: 5
ddb{0}> trace
x86_ipi_db(ffffffff826d7ff0) at x86_ipi_db+0x1a sys/arch/amd64/amd64/db_interface.c:352
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x23
__sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc
pipe_poll(fffffd806fc0d720,1,ffff8000fffff648) at pipe_poll+0x17c sys/kern/sys_pipe.c:738
selscan(ffff8000fffff648,ffff800020e14810,ffff800020e1481c,c,4,ffff800020e149f0) at selscan+0x14d sys/kern/sys_generic.c:722
dopselect(ffff8000fffff648,c,4317bb3ef20,432490e29e0,0,0) at dopselect+0x8b7 sys/kern/sys_generic.c:643
sys_select(ffff8000fffff648,ffff800020e149a0,ffff800020e149f0) at sys_select+0x8b sys/kern/sys_generic.c:542
syscall(ffff800020e14a70) at syscall+0x4a1 mi_syscall sys/sys/syscall_mi.h:102 [inline]
syscall(ffff800020e14a70) at syscall+0x4a1 sys/arch/amd64/amd64/trap.c:570
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7f7ffffd4ab0, count: -10
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(ffffffff823bf498) at panic+0x15e sys/kern/subr_prf.c:218
__assert(ffffffff8242d3f9,ffffffff8242c702,207,ffffffff823d1f6e) at __assert+0x2b sys/kern/subr_prf.c:162
kcov_remote_enter(0,ffff800020eb4bd8) at kcov_remote_enter+0x155 sys/dev/kcov.c:519
taskq_thread(ffff80000002c000) at taskq_thread+0xd9 sys/kern/kern_task.c:447
end trace frame: 0x0, count: 10
ddb{1}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff823bf498) at panic+0x15e sys/kern/subr_prf.c:218
__assert(ffffffff8242d3f9,ffffffff8242c702,207,ffffffff823d1f6e) at __assert+0x2b sys/kern/subr_prf.c:162
kcov_remote_enter(0,ffff800020eb4bd8) at kcov_remote_enter+0x155 sys/dev/kcov.c:519
taskq_thread(ffff80000002c000) at taskq_thread+0xd9 sys/kern/kern_task.c:447
end trace frame: 0x0, count: -5

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/08/15 00:59 openbsd 3abf65ea30ec c2707aa5 .config console log report ci-openbsd-multicore
2020/08/13 12:11 openbsd 0a23da6d899c ee7cb8b6 .config console log report ci-openbsd-multicore
* Struck through repros no longer work on HEAD.