syzbot


assert "fp->f_count >= NUM" failed in kern_descrip.c

Status: upstream: reported on 2024/03/24 06:26
Reported-by: syzbot+7f565bd02b19dd5fd066@syzkaller.appspotmail.com
First crash: 80d, last: 80d

Sample crash report:
panic: kernel diagnostic assertion "fp->f_count >= 2" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_descrip.c", line 1232 count (1) < 2
Stopped at      db_enter+0x1c:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff828d6a41) at panic+0x17b sys/kern/subr_prf.c:198
closef(fffffd8066f613a8,ffff80002f8e12b0) at closef+0x187 sys/kern/kern_descrip.c:1232
fdfree(ffff80002f8e12b0) at fdfree+0xe4 sys/kern/kern_descrip.c:1190
exit1(ffff80002f8e12b0,0,0,1) at exit1+0x3a0 sys/kern/kern_exit.c:199
sys_exit(ffff80002f8e12b0,ffff80002a1b25d0,ffff80002a1b2530) at sys_exit+0x1a sys/kern/kern_exit.c:89
syscall(ffff80002a1b25d0) at syscall+0x53b mi_syscall sys/sys/syscall_mi.h:183 [inline]
syscall(ffff80002a1b25d0) at syscall+0x53b sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x79cad1cb97c0, count: 7
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{0}> 
ddb{0}> set $lines = 0
ddb{0}> set $maxwidth = 0
ddb{0}> show panic
*cpu0: kernel diagnostic assertion "fp->f_count >= 2" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_descrip.c", line 1232 count (1) < 2
ddb{0}> trace
db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff828d6a41) at panic+0x17b sys/kern/subr_prf.c:198
closef(fffffd8066f613a8,ffff80002f8e12b0) at closef+0x187 sys/kern/kern_descrip.c:1232
fdfree(ffff80002f8e12b0) at fdfree+0xe4 sys/kern/kern_descrip.c:1190
exit1(ffff80002f8e12b0,0,0,1) at exit1+0x3a0 sys/kern/kern_exit.c:199
sys_exit(ffff80002f8e12b0,ffff80002a1b25d0,ffff80002a1b2530) at sys_exit+0x1a sys/kern/kern_exit.c:89
syscall(ffff80002a1b25d0) at syscall+0x53b mi_syscall sys/sys/syscall_mi.h:183 [inline]
syscall(ffff80002a1b25d0) at syscall+0x53b sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x79cad1cb97c0, count: -8
ddb{0}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80002a1b22d0
rbx               0xffffffff82c97cb7    cpu_info_full_primary+0x2cb7
rdx                                0
rcx               0xffff80002f8e12b0
rax               0xffffffff82c96ff0    cpu_info_full_primary+0x1ff0
r8                 0x101010101010101
r9                0x8080808080808080
r10               0x58d72cc72836f4db
r11               0xd8404430abd27658
r12               0xffffffff82c97ab8    cpu_info_full_primary+0x2ab8
r13                                0
r14                                0
r15                              0x1
rip               0xffffffff822e5afc    db_enter+0x1c
cs                               0x8
rflags                         0x246
rsp               0xffff80002a1b22c0
ss                              0x10
db_enter+0x1c:  addq    $0x8,%rsp
ddb{0}> show proc
PROC (syz-executor.0) tid=407856 pid=98725 tcnt=1 stat=onproc
    flags process=1008<EXITING,SINGLEEXIT> proc=2000<WEXIT>
    runpri=32, usrpri=86, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0xffff80002f8e12b0
    forw=0xffffffffffffffff, list=0xffff80002a210aa0,0xffff80002f8e2800
    process=0xffff800033b2df38 user=0xffff80002a1ad000, vmspace=0xfffffd806b743718
    estcpu=36, cpticks=2, pctcpu=0.0, user=0, sys=2, intr=0
ddb{0}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 77607  303285  98595      0  2           0                syz-executor.6
 77607  497434  98595      0  2   0x4000000                syz-executor.6
 77607  284500  98595      0  2   0x4000000                syz-executor.6
 38354  128542  98778      0  2           0                syz-executor.4
 38354   53218  98778      0  3   0x4000080  fsleep        syz-executor.4
 70634  314689  71647      0  2           0                syz-executor.3
 70634  272427  71647      0  3   0x4000080  fsleep        syz-executor.3
 12483  235548  83347      0  2           0                syz-executor.7
 12483  248530  83347      0  3   0x4000080  bell          syz-executor.7
 46059   45866  94173      0  2           0                syz-executor.5
 46059  318392  94173      0  3   0x4000080  fsleep        syz-executor.5
 43100  153134  25367      0  3        0x80  nanoslp       syz-executor.2
 43100  106061  25367      0  3   0x4000080  netio         syz-executor.2
 43100   68611  25367      0  3   0x4000080  fsleep        syz-executor.2
 71647   96009   7852      0  3        0x82  nanoslp       syz-executor.3
 83347  478521   7852      0  3        0x82  nanoslp       syz-executor.7
 94173  108120   7852      0  3        0x82  nanoslp       syz-executor.5
  7394  181038   7852      0  3        0x82  nanoslp       syz-executor.0
 25367   84538   7852      0  3        0x82  nanoslp       syz-executor.2
 98576  267948      0      0  3     0x14200  acct          acct
 97022   59501   7852      0  3        0x82  nanoslp       syz-executor.1
 52731  116649      0      0  3     0x14280  nfsidl        nfsio
 64673  353162      0      0  3     0x14280  nfsidl        nfsio
 63192  481571      0      0  3     0x14280  nfsidl        nfsio
 81644  289675      0      0  3     0x14280  nfsidl        nfsio
  7253  309556      0      0  3     0x14280  nfsidl        nfsio
 31024  296981      0      0  3     0x14280  nfsidl        nfsio
 50509  143292      0      0  3     0x14280  nfsidl        nfsio
 18738   32073      0      0  3     0x14280  nfsidl        nfsio
 49641  511718      0      0  3     0x14280  nfsidl        nfsio
 69369  197880      0      0  3     0x14280  nfsidl        nfsio
  3904  195418      0      0  3     0x14280  nfsidl        nfsio
 28851   94075      0      0  3     0x14280  nfsidl        nfsio
 92918  349361      0      0  3     0x14280  nfsidl        nfsio
 11076  276852      0      0  3     0x14280  nfsidl        nfsio
 64087  422803      0      0  3     0x14280  nfsidl        nfsio
 81105  419790      0      0  3     0x14280  nfsidl        nfsio
 88585  209398      0      0  3     0x14280  nfsidl        nfsio
 62975  135374      0      0  3     0x14280  nfsidl        nfsio
 48796  392577      0      0  3     0x14280  nfsidl        nfsio
  7493  232800      0      0  3     0x14280  nfsidl        nfsio
 98595  169499   7852      0  3        0x82  nanoslp       syz-executor.6
 98778   88269   7852      0  3        0x82  nanoslp       syz-executor.4
 10689    6164      1      0  3  0x18100083  ttyin         getty
   268  333502      0      0  3     0x14200  bored         sosplice
  7852  346032  21226      0  3  0x1a000082  kqread        syz-fuzzer
  7852  284364  21226      0  2  0x1e000002                syz-fuzzer
  7852  483528  21226      0  3  0x1e000082  wait          syz-fuzzer
  7852  461352  21226      0  3  0x1e000082  thrsleep      syz-fuzzer
  7852   93822  21226      0  3  0x1e000082  thrsleep      syz-fuzzer
  7852  266965  21226      0  3  0x1e000082  thrsleep      syz-fuzzer
  7852  222825  21226      0  3  0x1e000082  wait          syz-fuzzer
  7852  293024  21226      0  3  0x1e000082  wait          syz-fuzzer
  7852  181854  21226      0  2  0x1e000002                syz-fuzzer
  7852  157192  21226      0  3  0x1e000082  thrsleep      syz-fuzzer
  7852  210027  21226      0  3  0x1e000082  thrsleep      syz-fuzzer
  7852  426396  21226      0  3  0x1e000082  wait          syz-fuzzer
  7852  245494  21226      0  3  0x1e000082  wait          syz-fuzzer
  7852  412681  21226      0  3  0x1e000082  wait          syz-fuzzer
  7852   75008  21226      0  3  0x1e000082  wait          syz-fuzzer
  7852   90714  21226      0  3  0x1e000082  wait          syz-fuzzer
 21226  461345   1252      0  3   0x810008a  sigsusp       ksh
  1252   55754  47912      0  3  0x1800009a  kqread        sshd
 47912  206790      1      0  3  0x18000088  kqread        sshd
 69484  417756  12105     74  3  0x19100092  bpf           pflogd
 12105  190584      1      0  3  0x18000080  netio         pflogd
 32091  192839  50360     73  3  0x19100090  kqread        syslogd
 50360  348846      1      0  3  0x18100082  netio         syslogd
 47014  287545      1      0  3  0x18100080  kqread        resolvd
 18244  268619      0      0  3     0x14200  bored         smr
 88365  493146      0      0  2     0x14200                zerothread
 83489  452923      0      0  3     0x14200  aiodoned      aiodoned
  1765  433231      0      0  3     0x14200  syncer        update
 84430   87165      0      0  3     0x14200  cleaner       cleaner
 47165  303942      0      0  3     0x14200  reaper        reaper
 66187    9501      0      0  3     0x14200  pgdaemon      pagedaemon
 23105  113846      0      0  3     0x14200  bored         viomb
 80109  432781      0      0  3  0x40014200  acpi0         acpi0
 40323  329170      0      0  7  0x40014200                idle1
 55782  438826      0      0  3     0x14200  bored         softnet3
 58316  445079      0      0  3     0x14200  bored         softnet2
 65569   81150      0      0  3     0x14200  bored         softnet1
 80395  447334      0      0  3     0x14200  bored         softnet0
 35449  143224      0      0  3     0x14200  bored         systqmp
 29780   31528      0      0  3     0x14200  bored         systq
 17034  234589      0      0  3     0x14200  tmoslp        softclockmp
 23520   45402      0      0  3  0x40014200  tmoslp        softclock
 94634  103564      0      0  3  0x40014200                idle0
     1  373095      0      0  3   0x8080082  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb{0}> show all locks
ddb{0}> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 10234   6522K    8637K 166960K     30647        0
            pcb    15     32K      36K 166960K      7807        0
         rtable   251      8K       8K 166960K     14886        0
             pf    39     10K      11K 166960K      1457        0
         ifaddr    87     33K      36K 166960K      1511        0
        ifgroup    68      2K       3K 166960K      2369        0
         sysctl     4      1K       5K 166960K        45        0
       counters    70     37K      37K 166960K      1462        0
       ioctlops     0      0K       4K 166960K      5832        0
            iov     0      0K      32K 166960K      7597        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1764    111K     111K 166960K     23342        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       9K 166960K       829        0
         VM map     2      1K       1K 166960K         2        0
            sem    12      1K       1K 166960K        29        0
        dirhash     6      1K       2K 166960K       147        0
           ACPI  1697    195K     286K 166960K     12548        0
      file desc    17     61K      89K 166960K     75476        0
          sigio     0      0K       0K 166960K      2518        0
           proc    90     69K     116K 166960K     10372        0
        subproc   104      6K      10K 166960K      3223        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K      6764        0
       in_multi   103      7K       8K 166960K      3447        0
    ether_multi     1      0K       0K 166960K       100        0
            mrt     4      0K       0K 166960K        66        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys   277   1235K    1235K 166960K       277        0
           exec     0      0K       1K 166960K     11414        0
     pfkey data     0      0K       4K 166960K       103        0
            tdb     3      0K       0K 166960K         3        0
        VM swap     8     62K      64K 166960K        10        0
       UVM amap   630    917K     917K 166960K    718405        0
       UVM aobj   131      4K       4K 166960K       148        0
     pinsyscall    20     40K     108K 166960K      8819        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
    ip6_options     0      0K       0K 166960K      2702        0
            NDP    15      0K       1K 166960K      1183        0
           temp    74   6812K    7448K 166960K    757199        0
         kqueue     6     10K      30K 166960K      5287        0
      SYN cache     2   1504K    1512K 166960K         4        0
ddb{0}> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
plcache    128       24    0        0     1     0     1     1     0     8    0
rtpcb      120     6160    0     6159    76    75     1     5     0     8    0
rtentry    112     4350    0     4236     7     3     4     4     0     8    0
unpcb      144    57778    0    57768   452   446     6    10     0     8    5
syncache   336      738    0      738    99    99     0     1     0     8    0
sackhl      24       10   20       10     4     4     0     1     0     8    0
tcpqe       32      790    0      790    80    80     0     1     0     8    0
tcpcb      808    24023    0    23994   498   491     7    20     0     8    1
arp        120      945    0      923     1     0     1     1     0     8    0
ipq         40       11    0       11     4     4     0     1     0     8    0
ipqe        40       33    0       33     4     4     0     1     0     8    0
inpcb      392    64679    0    64650   711   704     7    24     0     8    2
nd6        136      731    0      707     1     0     1     1     0     8    0
pkpcb       40      394    0      394    58    58     0     1     0     8    0
kcovpl      48      229    0      221     1     0     1     1     0     8    0
ppxss      1168     265    0      265    71    71     0     1     0     8    0
pffrag     232      414    0      411     9     8     1     1     0   482    0
pffrnode    88      413    0      410     9     8     1     1     0     8    0
pffrent     40     4526    0     4523    10     9     1     1     0     8    0
pfosfp      40     1428    0     1005     5     0     5     5     0     8    0
pfosfpen   112     1428    0      714    21     0    21    21     0     8    0
pfstitem    24     2152    0     2123     1     0     1     1     0     8    0
pfstkey    128     2175    0     2146     7     5     2     3     0     8    0
pfstate    376     2175    0     2146    31    27     4     8     0     8    0
pfrule     1344      21    0       16     2     1     1     2     0     8    0
art_heap8  4096      49    0       48    11    10     1     3     0     8    0
art_heap4  256    13029    0    12565   101    72    29    34     0     8    0
art_table   32    13078    0    12613     6     2     4     5     0     8    0
art_node    16     4059    0     3958     1     0     1     1     0     8    0
semupl     112        1    0        1     1     1     0     1     0     8    0
semapl     112       14    0        4     1     0     1     1     0     8    0
shmpl      112      145    0       17     4     0     4     4     0     8    0
dirhash    1024     107    0      103     3     1     2     3     0     8    0
dino2pl    256   101310    0    99455   117     0   117   117     0     8    0
ffsino     272   101310    0    99455   125     0   125   125     0     8    0
nchpl      144   201760    0   200017    67     0    67    67     0     8    0
uvmvnodes   80    10176    0        0   208     0   208   208     0     8    0
vnodes     216    10176    0        0   566     0   566   566     0     8    0
namei      1024  681472    0   681472    12    11     1     2     0     8    1
percpumem   16      745    0      696     1     0     1     1     0     8    0
vcpupl     2048     518    0        6    65     0    65    65     0     8    0
vmpool     696      581    0       69    47     0    47    47     0     8    0
kstatmem   264     1422    0     1392    10     7     3     3     0     8    0
scxspl     216   588067    0   588067   135   134     1     8     1     8    1
plimitpl   152     7945    0     7930     1     0     1     1     0     8    0
sigapl     424    76687    0    76619    21    13     8     9     0     8    0
futexpl     64   627915    0   627911     3     2     1     1     0     8    0
knotepl    120     2986    0        0    19     3    16    19     0     8    0
kqueuepl   216    12730    0    12724   196   195     1     8     0     8    0
pipepl     320    11655    0    11627   296   293     3    12     0     8    0
fdescpl    496    75330    0    75303    25    21     4     5     0     8    0
filepl     152   446933    0   446705   549   535    14    23     0     8    4
filepl: pool(0xffffffff82e2d230:filepl): page inconsistency: page 0x0; at page head addr 0xfffffd8066f61f90 (p 0xfffffd8066f61000)
lockfpl    104    19707    0    19706    28    27     1     2     0     8    0
lockfspl    48     5598    0     5597     1     0     1     1     0     8    0
sessionpl  144      255    0      239     1     0     1     1     0     8    0
pgrppl      48     2023    0     2007     1     0     1     1     0     8    0
ucredpl    104    64847    0    64836     1     0     1     1     0     8    0
zombiepl   144    76621    0    76619     5     4     1     1     0     8    0
processpl  1136   76687    0    76619     6     0     6     6     0     8    0
procpl     680   200940    0   200849    28    19     9    10     0     8    0
srpgc       96      328    0      328    87    87     0     1     0     8    0
sosppl     168     1018    0     1012    17    16     1     1     0     8    0
sockpl     584   129218    0   129177   763   750    13    22     0     8    6
mcl64k     65536     73    0        0     4     1     3     3     0     8    0
mcl16k     16384     65    0        0     5     2     3     3     0     8    0
mcl12k     12288     41    0        0     2     0     2     2     0     8    0
mcl9k      9216      33    0        0     3     1     2     2     0     8    0
mcl8k      8192      90    0        0     4     1     3     3     0     8    0
mcl4k      4096      81    0        0     4     1     3     4     0     8    0
mcl2k2     2112      17    0        0     2     0     2     2     0     8    0
mcl2k      2048     848    0        0    34    21    13    31     0     8    0
mtagpl      96      399    0        0     8     2     6     8     0     8    0
mbufpl     256     9474    0        0   557     1   556   556     0     8    0
bufpl      280   130848    0   120671   734     6   728   728     0     8    0
anonpl      24  7044989    0  7029437   267   143   124   149     0   186    0
amapchunkpl 152 2287369    0  2286444   212   172    40    54     0   158    0
amappl16   200   141558    0   140940   526   487    39    57     0     8    0
amappl15   192      264    0      262     1     0     1     1     0     8    0
amappl14   184      901    0      883     5     3     2     2     0     8    0
amappl13   176       32    0       32     5     5     0     1     0     8    0
amappl12   168    79425    0    79380    24    21     3     3     0     8    0
amappl11   160       65    0       56     1     0     1     1     0     8    0
amappl10   152      375    0      355     2     0     2     2     0     8    0
amappl9    144      753    0      753    74    73     1     1     0     8    1
amappl8    136     3422    0     3108    13     0    13    13     0     8    0
amappl7    128      456    0      439     1     0     1     1     0     8    0
amappl6    120     3899    0     3854     5     3     2     2     0     8    0
amappl5    112     2453    0     2440     1     0     1     1     0     8    0
amappl4    104     3622    0     3562     3     1     2     3     0     8    0
amappl3     96   442171    0   442087     3     0     3     3     0     8    0
amappl2     88    79750    0    79645     9     6     3     4     0     8    0
amappl1     80   287742    0   287281    23     9    14    23     0     8    0
amappl      88   713908    0   713587    15     6     9     9     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      72      147    0       17     3     0     3     3     0     8    0
uaddrrnd    24    75911    0    75372     4     0     4     4     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24    75911    0    75372     4     0     4     4     0     8    0
vmmpekpl   168   478965    0   478850     6     0     6     6     0     8    0
vmmpepl    168  4486105    0  4482863  1390  1164   226   284     0   357   43
vmsppl     448    75910    0    75372    63     2    61    61     0     8    0
rwobjpl     56  1023070    0  1010763   248    74   174   176     0     8    0
pdppl      4096  151829    0   151256  2341  1765   576   585     0     8    3
pvpl        32    48795    0        0   395     1   394   395     0   265    0
pmappl     248    75910    0    75372    35     1    34    35     0     8    0
extentpl    40       56    0       38     1     0     1     1     0     8    0
phpool     112     4908    0     3320    46     0    46    46     0     8    0
ddb{0}> machine ddbcpu 0
Invalid cpu 0
ddb{0}> trace
db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff828d6a41) at panic+0x17b sys/kern/subr_prf.c:198
closef(fffffd8066f613a8,ffff80002f8e12b0) at closef+0x187 sys/kern/kern_descrip.c:1232
fdfree(ffff80002f8e12b0) at fdfree+0xe4 sys/kern/kern_descrip.c:1190
exit1(ffff80002f8e12b0,0,0,1) at exit1+0x3a0 sys/kern/kern_exit.c:199
sys_exit(ffff80002f8e12b0,ffff80002a1b25d0,ffff80002a1b2530) at sys_exit+0x1a sys/kern/kern_exit.c:89
syscall(ffff80002a1b25d0) at syscall+0x53b mi_syscall sys/sys/syscall_mi.h:183 [inline]
syscall(ffff80002a1b25d0) at syscall+0x53b sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x79cad1cb97c0, count: -8
ddb{0}> machine ddbcpu 1
Stopped at      x86_ipi_db+0x1e:        addq    $0x8,%rsp
x86_ipi_db(ffff800029cebff0) at x86_ipi_db+0x1e sys/arch/amd64/amd64/db_interface.c:393
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27
acpicpu_idle() at acpicpu_idle+0x2f1 sys/dev/acpi/acpicpu.c:1206
sched_idle(ffff800029cebff0) at sched_idle+0x41d sys/kern/kern_sched.c:183
end trace frame: 0x0, count: 10
ddb{1}> trace
x86_ipi_db(ffff800029cebff0) at x86_ipi_db+0x1e sys/arch/amd64/amd64/db_interface.c:393
x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27
acpicpu_idle() at acpicpu_idle+0x2f1 sys/dev/acpi/acpicpu.c:1206
sched_idle(ffff800029cebff0) at sched_idle+0x41d sys/kern/kern_sched.c:183
end trace frame: 0x0, count: -5

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/03/24 06:25 openbsd f7d60097d803 6ee49f2e .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore assert "fp->f_count >= NUM" failed in kern_descrip.c
* Struck through repros no longer work on HEAD.