syzbot


assert "kd_lookup(kd->kd_unit) == NULL" failed in kcov.c (5)

Status: upstream: reported on 2026/05/07 16:10
Reported-by: syzbot+96e50b1184ab4f28c0b6@syzkaller.appspotmail.com
First crash: 13d, last: 13d
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
openbsd assert "kd_lookup(kd->kd_unit) == NULL" failed in kcov.c (3) -1 2 340d 372d 0/3 auto-obsoleted due to no activity on 2025/09/12 14:51
openbsd assert "kd_lookup(kd->kd_unit) == NULL" failed in kcov.c (4) -1 3 114d 233d 0/3 auto-obsoleted due to no activity on 2026/04/26 16:11
openbsd assert "kd_lookup(kd->kd_unit) == NULL" failed in kcov.c -1 2 569d 607d 0/3 auto-obsoleted due to no activity on 2025/01/26 12:26
openbsd assert "kd_lookup(kd->kd_unit) == NULL" failed in kcov.c (2) -1 1 462d 462d 0/3 auto-obsoleted due to no activity on 2025/05/13 16:49

Sample crash report:
panic: kernel diagnostic assertion "kd_lookup(kd->kd_unit) == NULL" failed: file "/syzkaller/managers/main/kernel/sys/dev/kcov.c", line 306
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*193794  85690      0           0  0x4000000    0  syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83419cc9) at panic+0x1cf sys/kern/subr_prf.c:198
__assert(ffffffff83456e3b,ffffffff83469028,132,ffffffff834c1036) at __assert+0x29 sys/kern/subr_prf.c:-1
kcovopen(113d4,41,2000,ffff80002a7754d8) at kcovopen+0x14f kd_lookup sys/dev/kcov.c:478 [inline]
kcovopen(113d4,41,2000,ffff80002a7754d8) at kcovopen+0x14f sys/dev/kcov.c:306
spec_open_clone(ffff80003c506e68) at spec_open_clone+0x277 sys/kern/spec_vnops.c:722
spec_open(ffff80003c506e68) at spec_open+0x316 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd8065346970,41,fffffd8007ffd618,ffff80002a7754d8) at VOP_OPEN+0x82 sys/kern/vfs_vops.c:138
vn_open(ffff80003c5070c0,41,0) at vn_open+0x7a5 sys/kern/vfs_vnops.c:183
doopenat(ffff80002a7754d8,ffffff9c,200000000040,40,0,0,190133a8e123c6e0) at doopenat+0x352 sys/kern/vfs_syscalls.c:1155
sys_openat(ffff80002a7754d8,ffff80003c507360,ffff80003c5072b0) at sys_openat+0x58 sys/kern/vfs_syscalls.c:1094
syscall(ffff80003c507360) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c507360) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xa33ca45c220, count: 3
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: kernel diagnostic assertion "kd_lookup(kd->kd_unit) == NULL" failed: file "/syzkaller/managers/main/kernel/sys/dev/kcov.c", line 306
ddb> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83419cc9) at panic+0x1cf sys/kern/subr_prf.c:198
__assert(ffffffff83456e3b,ffffffff83469028,132,ffffffff834c1036) at __assert+0x29 sys/kern/subr_prf.c:-1
kcovopen(113d4,41,2000,ffff80002a7754d8) at kcovopen+0x14f kd_lookup sys/dev/kcov.c:478 [inline]
kcovopen(113d4,41,2000,ffff80002a7754d8) at kcovopen+0x14f sys/dev/kcov.c:306
spec_open_clone(ffff80003c506e68) at spec_open_clone+0x277 sys/kern/spec_vnops.c:722
spec_open(ffff80003c506e68) at spec_open+0x316 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd8065346970,41,fffffd8007ffd618,ffff80002a7754d8) at VOP_OPEN+0x82 sys/kern/vfs_vops.c:138
vn_open(ffff80003c5070c0,41,0) at vn_open+0x7a5 sys/kern/vfs_vnops.c:183
doopenat(ffff80002a7754d8,ffffff9c,200000000040,40,0,0,190133a8e123c6e0) at doopenat+0x352 sys/kern/vfs_syscalls.c:1155
sys_openat(ffff80002a7754d8,ffff80003c507360,ffff80003c5072b0) at sys_openat+0x58 sys/kern/vfs_syscalls.c:1094
syscall(ffff80003c507360) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c507360) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xa33ca45c220, count: -12
ddb> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80003c506c50
rbx                                0
rdx               0xffff8000015a9a80
rcx                                0
rax               0xffff80002a7754d8
r8                 0x101010101010101
r9                0x8080808080808080
r10               0x8d2447af84b4418f
r11               0xd4a5d14e3b40fbf6
r12                                0
r13                              0x2
r14                                0
r15                              0x1
rip               0xffffffff812dd435    db_enter+0x25
cs                               0x8
rflags                         0x246
rsp               0xffff80003c506c40
ss                              0x10
db_enter+0x25:  addq    $0x8,%rsp
ddb> show proc
PROC (syz-executor) tid=193794 pid=85690 tcnt=3 stat=onproc
    flags process=0 proc=4000000<THREAD>
    runpri=67, usrpri=68, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80002a7747e0,0xffff80002a7a4800
    process=0xffff8000ffffb198 user=0xffff80003c502000, vmspace=0xfffffd806cb26180
    estcpu=18, cpticks=2, pctcpu=0.0, user=0, sys=2, intr=0
ddb> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 47868  406435  55335      0  2           0                syz-executor
 47868   75337  55335      0  3   0x4000080  fsleep        syz-executor
 70245  502240  58548      0  2           0                syz-executor
 70245  267756  58548      0  3   0x4000080  fsleep        syz-executor
 94579   96555   3356      0  2           0                syz-executor
 94579   10262   3356      0  3   0x4000080  fsleep        syz-executor
 94579  326006   3356      0  3   0x4000080  netacc        syz-executor
 94579  292413   3356      0  3   0x4000080  fsleep        syz-executor
 98700  186732  10784      0  2           0                syz-executor
 98700  287822  10784      0  3   0x4000080  fsleep        syz-executor
 98700  228338  10784      0  3   0x4000080  fsleep        syz-executor
 98700  430512  10784      0  3   0x4000080  fsleep        syz-executor
 82247  207755  54439      0  2           0                syz-executor
 82247  391583  54439      0  3   0x4000080  fsleep        syz-executor
 82247  479624  54439      0  3   0x4000080  fsleep        syz-executor
 88507  170096  77231      0  2           0                syz-executor
 88507   41083  77231      0  3   0x4000080  fsleep        syz-executor
 88507   77400  77231      0  3   0x4000080  fsleep        syz-executor
 88507  162792  77231      0  3   0x4000080  fsleep        syz-executor
 85690   89122  70320      0  2           0                syz-executor
*85690  193794  70320      0  7   0x4000000                syz-executor
 85690  309432  70320      0  3   0x4000080  fsleep        syz-executor
 47676  488244  17721      0  2           0                syz-executor
 47676  174409  17721      0  3   0x4000080  fsleep        syz-executor
 47676  251433  17721      0  3   0x4000080  fsleep        syz-executor
 47676  286762  17721      0  3   0x4000080  fsleep        syz-executor
 46895   61260      0      0  3     0x14200  acct          acct
 55335  315851  53956      0  3        0x82  nanoslp       syz-executor
 17721  378074  53956      0  3        0x82  nanoslp       syz-executor
 54439  248079  53956      0  3        0x82  nanoslp       syz-executor
 10784  294002  53956      0  3        0x82  nanoslp       syz-executor
  3356  333533  53956      0  3        0x82  nanoslp       syz-executor
 77231  510058  53956      0  3        0x82  nanoslp       syz-executor
 70320  357927  53956      0  3        0x82  nanoslp       syz-executor
 58548  275729  53956      0  3        0x82  nanoslp       syz-executor
 53956  200286  52355      0  3        0x82  kqread        syz-executor
 52355  190489  50765      0  3    0x10008a  sigsusp       ksh
 50765  370827  45091      0  3        0x98  kqread        sshd-session
 45091   84324  74381      0  3        0x92  kqread        sshd-session
 76949   36522      1      0  3    0x100083  ttyin         getty
 74381   28095      1      0  3        0x88  kqread        sshd
 69076  168293  69512     73  3   0x1100090  kqread        syslogd
 69512  110459      1      0  3    0x100082  sbwait        syslogd
 51633  138037      1      0  3    0x100080  kqread        resolvd
 31242  291339  34041     77  3    0x100092  kqread        dhcpleased
 84204  322804  34041     77  3    0x100092  kqread        dhcpleased
 34041  140013      1      0  3        0x80  kqread        dhcpleased
 84367  308005      0      0  3     0x14200  bored         smr
 60533  192468      0      0  2     0x14200                zerothread
 25259  505192      0      0  3     0x14200  aiodoned      aiodoned
 31766  129443      0      0  3     0x14200  syncer        update
 73777  281927      0      0  3     0x14200  cleaner       cleaner
 52155  270550      0      0  3     0x14200  reaper        reaper
 17247  101891      0      0  3     0x14200  pgdaemon      pagedaemon
 34375  121431      0      0  3     0x14200  bored         viomb
  9439  184165      0      0  3  0x40014200  acpi0         acpi0
 12035  361145      0      0  3     0x14200  bored         softnet0
 74212  279060      0      0  3     0x14200  bored         systqmp
 96678   61653      0      0  3     0x14200  bored         systq
 83911   13424      0      0  3  0x40014200  tmoslp        softclock
 68575   15124      0      0  3  0x40014200                idle0
     1  344917      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 11025  12160K   12316K 166960K     12254        0
            pcb    21     14K      15K 166960K        81        0
         rtable   167      5K       7K 166960K       398        0
             pf    26     12K      14K 166960K        47        0
         ifaddr    28      4K       7K 166960K        51        0
        ifgroup    39      1K       2K 166960K        65        0
         sysctl     3      1K       9K 166960K         7        0
       counters    30     17K      18K 166960K        38        0
       ioctlops     0      0K       4K 166960K        73        0
            iov     0      0K      12K 166960K        66        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1302     82K      82K 166960K      1495        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       5K 166960K         3        0
         VM map     2      1K       1K 166960K         2        0
            sem     3      0K       0K 166960K         4        0
        dirhash    12      2K       2K 166960K        12        0
           ACPI  1692    195K     286K 166960K     12470        0
      file desc    18     65K      97K 166960K       275        0
           proc    58     59K     124K 166960K       508        0
        subproc    74      4K       4K 166960K        76        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K        32        0
       in_multi    55      4K       6K 166960K        99        0
    ether_multi     1      0K       0K 166960K         2        0
            mrt     0      0K       0K 166960K        12        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys    49    228K     228K 166960K        49        0
           exec     0      0K       1K 166960K       373        0
   fusefs mount     1     32K      32K 166960K         1        0
            tdb     3      0K       0K 166960K         3        0
        VM swap     8     62K      64K 166960K        10        0
       UVM amap   244    143K     159K 166960K      4240        0
       UVM aobj     6      2K       2K 166960K         6        0
     pinsyscall    39     78K      96K 166960K      1366        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
    ip6_options     0      0K       0K 166960K         4        0
            NDP     8      0K       1K 166960K        32        0
           temp    37   9066K    9130K 166960K      5275        0
         kqueue    13     20K      24K 166960K        45        0
      SYN cache     2     16K      16K 166960K         2        0
ddb> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
rtpcb      120       50    0       47     1     0     1     1     0     8    0
rtentry    136      118    0       49     4     0     4     4     0     8    0
unpcb      144       89    0       71     1     0     1     1     0     8    0
syncache   336       10    0       10     2     1     1     1     0     8    1
tcpqe       32        2    0        2     2     1     1     1     0     8    1
tcpcb      736       96    0       84     2     0     2     2     0     8    0
arp         96       18    0        8     1     0     1     1     0     8    0
inpcb      328      360    0      330     8     5     3     7     0     8    0
nd6        112       25    0       13     1     0     1     1     0     8    0
kcovpl      48        8    0        0     1     0     1     1     0     8    0
ppxss      1072       3    0        3     2     1     1     1     0     8    1
pftag       88        1    0        0     1     0     1     1     0     8    0
pfqueue    320        8    0        0     1     0     1     1     0     8    0
pfrule     1360       4    0        3     1     0     1     1     0     8    0
art_heap8  4096       2    0        0     2     0     2     2     0     8    0
art_heap4  256      461    0      178    29     2    27    29     0     8    4
art_table   40      463    0      178     5     0     5     5     0     8    0
art_node    32      118    0       56     1     0     1     1     0     8    0
semapl     112        2    0        1     1     0     1     1     0     8    0
shmpl      112        3    0        0     1     0     1     1     0     8    0
dirhash    1024      17    0        0     3     0     3     3     0     8    0
dino2pl    256     1812    0      355    92     0    92    92     0     8    0
ffsino     256     1812    0      355    92     0    92    92     0     8    0
nchpl      144     2189    0      493    63     0    63    63     0     8    0
vnodes     216     1971    0        0   110     0   110   110     0     8    0
namei      1024    6389    0     6389     1     0     1     1     0     8    1
kstatmem   264       33    0       16     2     0     2     2     0     8    0
scsiplug    72        1    0        1     1     1     0     1     0     8    0
scxspl     216     6915    0     6915     3     2     1     3     1     8    1
plimitpl   152       52    0       35     1     0     1     1     0     8    0
sigapl     424      568    0      524     7     1     6     6     0     8    1
knotepl    120     7583    0     7536     2     0     2     2     0     8    0
kqueuepl   184      135    0      123     4     3     1     4     0     8    0
pipepl     304      119    0       92     3     0     3     3     0     8    0
fdescpl    448      554    0      524     5     1     4     5     0     8    0
filepl     120     2392    0     2151    13     5     8    12     0     8    0
lockfpl    104       35    0       32     1     0     1     1     0     8    0
lockfspl    48       18    0       15     1     0     1     1     0     8    0
sessionpl  144       22    0       14     1     0     1     1     0     8    0
pgrppl      48       30    0       14     1     0     1     1     0     8    0
ucredpl    104      192    0      181     1     0     1     1     0     8    0
zombiepl   144      567    0      567     1     0     1     1     0     8    1
processpl  1152     568    0      524     4     0     4     4     0     8    0
procpl     664      775    0      713     6     0     6     6     0     8    0
sockpl     552      500    0      449     8     4     4     7     0     8    0
mcl64k     65536     41    0       41     2     1     1     1     0     8    1
mcl16k     16384     14    0       14     2     1     1     1     0     8    1
mcl12k     12288      3    0        3     2     1     1     1     0     8    1
mcl9k128   9344       3    0        3     2     1     1     1     0     8    1
mcl8k      8192      34    0       34     1     0     1     1     0     8    1
mcl4k      4096    2779    0     2729    15     7     8    14     0     8    1
mcl2k2     2112       3    0        3     2     1     1     1     0     8    1
mcl2k      2048     247    0      247     2     1     1     2     0     8    1
mtagpl      96        4    0        4     1     1     0     1     0     8    0
mbufpl     256     6039    0     5915    11     0    11    11     0     8    0
bufpl      280     2468    0      102   169     0   169   169     0     8    0
anonpl      24   116207    0   112897    35     3    32    32     0   187   11
amapchunkpl 152   12478    0    11929    25     1    24    24     0   158    2
amappl16   200     2177    0     2155     5     3     2     5     0     8    0
amappl15   192        6    0        6     1     1     0     1     0     8    0
amappl14   184      408    0      407     1     0     1     1     0     8    0
amappl13   176      127    0      117     1     0     1     1     0     8    0
amappl12   168      795    0      766     2     0     2     2     0     8    0
amappl11   160        8    0        8     1     1     0     1     0     8    0
amappl10   152       63    0       53     1     0     1     1     0     8    0
amappl9    144      270    0      270     1     1     0     1     0     8    0
amappl8    136      100    0       99     1     0     1     1     0     8    0
amappl7    128      141    0      130     1     0     1     1     0     8    0
amappl6    120      153    0      152     1     0     1     1     0     8    0
amappl5    112       89    0       82     1     0     1     1     0     8    0
amappl4    104      265    0      249     1     0     1     1     0     8    0
amappl3     96     2312    0     2188     4     0     4     4     0     8    0
amappl2     88      510    0      459     2     0     2     2     0     8    0
amappl1     80     9916    0     9367    16     1    15    15     0     8    2
amappl      88     3519    0     3337     5     0     5     5     0    92    0
uvmvnodes   80       98    0        0     2     0     2     2     0     8    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      72        5    0        0     1     0     1     1     0     8    0
uaddrrnd    24      554    0      524     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24      554    0      524     1     0     1     1     0     8    0
vmmpekpl   168     6157    0     6127     2     0     2     2     0     8    0
vmmpepl    168    43513    0    41678    92     2    90    90     0   357    9
vmsppl     368      553    0      524     4     1     3     4     0     8    0
rwobjpl     40    15361    0    14396    12     0    12    12     0     8    0
pdppl      4096    1114    0     1048   102    34    68    82     0     8    2
pvpl        32   276167    0   266956    95     1    94    94     0   265   16
pmappl     216      553    0      524     3     0     3     3     0     8    0
extentpl    40       45    0       27     1     0     1     1     0     8    0
phpool     112      371    0       51    10     0    10    10     0     8    0
ddb> machine ddbcpu 0
No such command
ddb> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83419cc9) at panic+0x1cf sys/kern/subr_prf.c:198
__assert(ffffffff83456e3b,ffffffff83469028,132,ffffffff834c1036) at __assert+0x29 sys/kern/subr_prf.c:-1
kcovopen(113d4,41,2000,ffff80002a7754d8) at kcovopen+0x14f kd_lookup sys/dev/kcov.c:478 [inline]
kcovopen(113d4,41,2000,ffff80002a7754d8) at kcovopen+0x14f sys/dev/kcov.c:306
spec_open_clone(ffff80003c506e68) at spec_open_clone+0x277 sys/kern/spec_vnops.c:722
spec_open(ffff80003c506e68) at spec_open+0x316 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd8065346970,41,fffffd8007ffd618,ffff80002a7754d8) at VOP_OPEN+0x82 sys/kern/vfs_vops.c:138
vn_open(ffff80003c5070c0,41,0) at vn_open+0x7a5 sys/kern/vfs_vnops.c:183
doopenat(ffff80002a7754d8,ffffff9c,200000000040,40,0,0,190133a8e123c6e0) at doopenat+0x352 sys/kern/vfs_syscalls.c:1155
sys_openat(ffff80002a7754d8,ffff80003c507360,ffff80003c5072b0) at sys_openat+0x58 sys/kern/vfs_syscalls.c:1094
syscall(ffff80003c507360) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c507360) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xa33ca45c220, count: -12
ddb> machine ddbcpu 1
No such command
ddb> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83419cc9) at panic+0x1cf sys/kern/subr_prf.c:198
__assert(ffffffff83456e3b,ffffffff83469028,132,ffffffff834c1036) at __assert+0x29 sys/kern/subr_prf.c:-1
kcovopen(113d4,41,2000,ffff80002a7754d8) at kcovopen+0x14f kd_lookup sys/dev/kcov.c:478 [inline]
kcovopen(113d4,41,2000,ffff80002a7754d8) at kcovopen+0x14f sys/dev/kcov.c:306
spec_open_clone(ffff80003c506e68) at spec_open_clone+0x277 sys/kern/spec_vnops.c:722
spec_open(ffff80003c506e68) at spec_open+0x316 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd8065346970,41,fffffd8007ffd618,ffff80002a7754d8) at VOP_OPEN+0x82 sys/kern/vfs_vops.c:138
vn_open(ffff80003c5070c0,41,0) at vn_open+0x7a5 sys/kern/vfs_vnops.c:183
doopenat(ffff80002a7754d8,ffffff9c,200000000040,40,0,0,190133a8e123c6e0) at doopenat+0x352 sys/kern/vfs_syscalls.c:1155
sys_openat(ffff80002a7754d8,ffff80003c507360,ffff80003c5072b0) at sys_openat+0x58 sys/kern/vfs_syscalls.c:1094
syscall(ffff80003c507360) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c507360) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xa33ca45c220, count: -12

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/07 16:09 openbsd d8525c0ee876 340bcdf0 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main assert "kd_lookup(kd->kd_unit) == NULL" failed in kcov.c
* Struck through repros no longer work on HEAD.