syzbot


assert "ISSET(p->p_flag, P_SUSPSIG | P_SUSPSINGLE) == NUM" failed in kern_sig.c

Status: upstream: reported on 2026/04/30 00:50
Reported-by: syzbot+65bf0a9d1cc48d8c3760@syzkaller.appspotmail.com
First crash: 1d18h, last: 1d18h

Sample crash report:
panic: kernel diagnostic assertion "ISSET(p->p_flag, P_SUSPSIG | P_SUSPSINGLE) == 0" failed: file "/syzkaller/managers/setuid/kernel/sys/kern/kern_sig.c", line 1602
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*446828      8  32767      0xa011  0x4080000    0  syz-executor
 114067  67528  32767        0x10          0    1  syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83454ec5) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff8348f2e8,ffffffff834883dd,642,ffffffff833d7ba0) at __assert+0x29 sys/kern/subr_prf.c:-1
process_stop(ffff80003c3e4020,8000000,1) at process_stop+0x3fe
cursig(ffff80003c3dfcb8,ffff80003c41d6f8,0) at cursig+0x509 x86_atomic_setbits_u32 sys/arch/amd64/compile/SYZKALLER/obj/machine/atomic.h:-1 [inline]
cursig(ffff80003c3dfcb8,ffff80003c41d6f8,0) at cursig+0x509 sys/kern/kern_sig.c:1445
userret(ffff80003c3dfcb8) at userret+0x203 sys/kern/kern_sig.c:2207
syscall(ffff80003c41d830) at syscall+0x9ce mi_syscall_return sys/sys/syscall_mi.h:203 [inline]
syscall(ffff80003c41d830) at syscall+0x9ce sys/arch/amd64/amd64/trap.c:804
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x1eedb82c050, 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 "ISSET(p->p_flag, P_SUSPSIG | P_SUSPSINGLE) == 0" failed: file "/syzkaller/managers/setuid/kernel/sys/kern/kern_sig.c", line 1602
ddb{0}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83454ec5) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff8348f2e8,ffffffff834883dd,642,ffffffff833d7ba0) at __assert+0x29 sys/kern/subr_prf.c:-1
process_stop(ffff80003c3e4020,8000000,1) at process_stop+0x3fe
cursig(ffff80003c3dfcb8,ffff80003c41d6f8,0) at cursig+0x509 x86_atomic_setbits_u32 sys/arch/amd64/compile/SYZKALLER/obj/machine/atomic.h:-1 [inline]
cursig(ffff80003c3dfcb8,ffff80003c41d6f8,0) at cursig+0x509 sys/kern/kern_sig.c:1445
userret(ffff80003c3dfcb8) at userret+0x203 sys/kern/kern_sig.c:2207
syscall(ffff80003c41d830) at syscall+0x9ce mi_syscall_return sys/sys/syscall_mi.h:203 [inline]
syscall(ffff80003c41d830) at syscall+0x9ce sys/arch/amd64/amd64/trap.c:804
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x1eedb82c050, count: -8
ddb{0}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80003c41d510
rbx               0xffffffff83945e07    cpu_info_full_primary+0x2e07
rdx                                0
rcx               0xffff80003c3dfcb8
rax               0xffffffff83944ff0    cpu_info_full_primary+0x1ff0
r8                 0x101010101010101
r9                0x8080808080808080
r10               0xe5190105adb4e660
r11               0x4352d13181e7096d
r12               0xffffffff83945c08    cpu_info_full_primary+0x2c08
r13                                0
r14                                0
r15                              0x1
rip               0xffffffff828baef5    db_enter+0x25
cs                               0x8
rflags                         0x246
rsp               0xffff80003c41d500
ss                              0x10
db_enter+0x25:  addq    $0x8,%rsp
ddb{0}> show proc
PROC (syz-executor) tid=446828 pid=8 tcnt=4 stat=onproc
    flags process=a011<CONTROLT,SUGID,SINGLEUNWIND,STOPPING> proc=4080000<SUSPSINGLE,THREAD>
    runpri=32, usrpri=50, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0xffff80003c3e3250 scnt=2 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80003c3e22c0,0xffffffff83987898
    process=0xffff80003c3e4020 user=0xffff80003c418000, vmspace=0xfffffd800f447b98
    estcpu=36, cpticks=0, pctcpu=0.0, user=0, sys=0, intr=0
ddb{0}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
     8  164744  16595  32767  2     0x8a011                syz-executor
     8   80753  16595  32767  4   0x408a011                syz-executor
     8  451715  16595  32767  3   0x400a011  suspend       syz-executor
*    8  446828  16595  32767  7   0x408a011                syz-executor
 67528  114067  87986  32767  7        0x10                syz-executor
 67528   87716  87986  32767  3   0x4000090  lockf         syz-executor
 67528  108311  87986  32767  3   0x4000090  lockf         syz-executor
 87358  235125  68495  32767  3        0x90  nanoslp       syz-executor
 87358  449957  68495  32767  3   0x4000090  sbwait        syz-executor
 87358  308395  68495  32767  3   0x4000090  fsleep        syz-executor
 38127  263616  34146  32767  3        0x90  nanoslp       syz-executor
 38127  390284  34146  32767  3   0x4000090  kqsel         syz-executor
 38127   93403  34146  32767  3   0x4000090  fsleep        syz-executor
 78327   34519  17018  32767  3        0x90  nanoslp       syz-executor
 78327  287353  17018  32767  3   0x4000090  semwait       syz-executor
 78327  428546  17018  32767  3   0x4000090  fsleep        syz-executor
  7758  302417  55989  32767  3        0x90  nanoslp       syz-executor
  7758  423011  55989  32767  3   0x4000090  lockf         syz-executor
  7758  261635  55989  32767  3   0x4000090  fsleep        syz-executor
 68495   13420  65570  32767  3        0x90  nanoslp       syz-executor
 87986    2589  90091  32767  3        0x90  nanoslp       syz-executor
 95318  278420  35686  32767  3        0x90  wait          syz-executor
 16595  122291  35542  32767  3        0x90  nanoslp       syz-executor
 85361  162175  66857  32767  3        0x90  nanoslp       syz-executor
 34146  386768  38550  32767  3        0x90  nanoslp       syz-executor
 55989   46974   2411  32767  3        0x90  nanoslp       syz-executor
 17018  312728  11324  32767  3        0x90  nanoslp       syz-executor
 35542  184309  52737      0  3        0x82  wait          syz-executor
 65570   20408  52737      0  3        0x82  wait          syz-executor
 66857  115621  52737      0  3        0x82  wait          syz-executor
 11324   59153  52737      0  3        0x82  wait          syz-executor
 90091   27811  52737      0  3        0x82  wait          syz-executor
 35686  217034  52737      0  3        0x82  wait          syz-executor
 38550  511849  52737      0  3        0x82  wait          syz-executor
  2411  137596  52737      0  3        0x82  wait          syz-executor
 52737  384420  93080      0  3        0x82  kqread        syz-executor
 93080  486741  21574      0  3    0x10008a  sigsusp       ksh
 21574  285955  14143      0  3        0x98  kqread        sshd-session
 14143  509593  75564      0  3        0x92  kqread        sshd-session
 95678  353636      1      0  3    0x100083  ttyin         getty
 75564    8207      1      0  3        0x88  kqread        sshd
  8740  354451  20606     73  3   0x1100090  kqread        syslogd
 20606  216407      1      0  3    0x100082  sbwait        syslogd
 65512  496717      1      0  3    0x100080  kqread        resolvd
 51109  205614   7718     77  3    0x100092  kqread        dhcpleased
 76962  411536   7718     77  3    0x100092  kqread        dhcpleased
  7718  225076      1      0  3        0x80  kqread        dhcpleased
 47051  125042      0      0  3     0x14200  bored         smr
 60883  100245      0      0  3     0x14200  pgzero        zerothread
 93412  362524      0      0  3     0x14200  aiodoned      aiodoned
 13062  196620      0      0  3     0x14200  syncer        update
 90958  322448      0      0  3     0x14200  cleaner       cleaner
 27072  336265      0      0  3     0x14200  reaper        reaper
 51297  356575      0      0  3     0x14200  pgdaemon      pagedaemon
 87251  300176      0      0  3     0x14200  bored         viomb
  5625  180285      0      0  3  0x40014200  acpi0         acpi0
 80033  401971      0      0  3  0x40014200                idle1
 93553  466394      0      0  3     0x14200  bored         softnet1
 38312   63584      0      0  3     0x14200  bored         softnet0
  9999  455675      0      0  3     0x14200  bored         systqmp
 53474  190212      0      0  3     0x14200  bored         systq
 96676  512833      0      0  3     0x14200  tmoslp        softclockmp
 29417  156780      0      0  3  0x40014200  tmoslp        softclock
 93637   82381      0      0  3  0x40014200                idle0
     1  483455      0      0  3        0x82  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb{0}> show all locks
CPU 0:
exclusive mutex &sched_lock r = 0 (0xffffffff83a192b0)
#0  witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0  witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1  mtx_enter+0x4b4 sys/kern/kern_lock.c:487
#2  cursig+0x4ee sys/kern/kern_sig.c:1444
#3  userret+0x203 sys/kern/kern_sig.c:2207
#4  syscall+0x9ce mi_syscall_return sys/sys/syscall_mi.h:203 [inline]
#4  syscall+0x9ce sys/arch/amd64/amd64/trap.c:804
#5  Xsyscall+0x128
exclusive mutex &pr->ps_mtx r = 0 (0xffff80003c3e4138)
#0  witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0  witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1  mtx_enter+0x4b4 sys/kern/kern_lock.c:487
#2  cursig+0x4c2 sys/kern/kern_sig.c:1440
#3  userret+0x203 sys/kern/kern_sig.c:2207
#4  syscall+0x9ce mi_syscall_return sys/sys/syscall_mi.h:203 [inline]
#4  syscall+0x9ce sys/arch/amd64/amd64/trap.c:804
#5  Xsyscall+0x128
ddb{0}> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11067  12020K   12034K 166960K     12159        0
            pcb    17     12K      12K 166960K        17        0
         rtable   243      6K       7K 166960K       389        0
             pf    31     16K      16K 166960K        31        0
         ifaddr    42      7K       7K 166960K        44        0
        ifgroup    50      2K       2K 166960K        50        0
         sysctl     4      1K       9K 166960K         9        0
       counters    70     37K      37K 166960K        70        0
       ioctlops     0      0K       4K 166960K        45        0
            iov     0      0K      24K 166960K       118        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1288     81K      81K 166960K      1470        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       9K 166960K        15        0
         VM map     2      1K       1K 166960K         2        0
            sem    13      1K       1K 166960K        31        0
        dirhash    12      2K       2K 166960K        21        0
           ACPI  1692    195K     286K 166960K     12470        0
      file desc    26     97K     129K 166960K       749        0
          sigio     1      0K       0K 166960K        20        0
           proc    58     99K     163K 166960K       579        0
        subproc    72      4K       4K 166960K        72        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K       134        0
       in_multi    99      7K       7K 166960K       112        0
    ether_multi     1      0K       0K 166960K         3        0
            mrt     0      0K       0K 166960K        17        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys   145    652K     652K 166960K       145        0
           exec     0      0K       1K 166960K       528        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   276    168K     191K 166960K      8928        0
       UVM aobj    94      3K       3K 166960K        96        0
     pinsyscall    47     94K     114K 166960K      1893        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
    ip6_options     0      0K       0K 166960K        39        0
            NDP    11      0K       2K 166960K        27        0
           temp    75   9088K    9152K 166960K      6728        0
         kqueue    13     20K      31K 166960K       140        0
      SYN cache     2     16K      16K 166960K         2        0
ddb{0}> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
plcache    128       26    0        0     1     0     1     1     0     8    0
rtpcb      120       78    0       74     1     0     1     1     0     8    0
rtentry    176      120    0        7     6     0     6     6     0     8    0
unpcb      144      580    0      562     4     2     2     4     0     8    1
syncache   336       14    0       14     1     0     1     1     0     8    1
tcpqe       32        1    0        1     1     0     1     1     0     8    1
tcpcb      736      482    0      476     8     1     7     7     0     8    6
arp        136       19    0        0     1     0     1     1     0     8    0
ipq         40        2    0        0     1     0     1     1     0     8    0
ipqe        40        7    0        5     1     0     1     1     0     8    0
inpcb      328      894    0      815     8     1     7     7     0     8    0
ip6q        72        3    0        2     1     0     1     1     0     8    0
ip6af       40        5    0        4     1     0     1     1     0     8    0
nd6        152       32    0        6     2     0     2     2     0     8    0
kcovpl      48        8    0        0     1     0     1     1     0     8    0
art_heap8  4096       1    0        0     1     0     1     1     0     8    0
art_heap4  256      514    0       44    31     0    31    31     0     8    1
art_table   40      515    0       44     5     0     5     5     0     8    0
art_node    32      120    0       17     1     0     1     1     0     8    0
sysvmsgpl   40        2    0        1     1     0     1     1     0     8    0
semupl     112        2    0        2     1     1     0     1     0     8    0
semapl     112       26    0       16     1     0     1     1     0     8    0
shmpl      112       93    0        2     3     0     3     3     0     8    0
dirhash    1024      23    0        6     3     0     3     3     0     8    0
dino2pl    256     2519    0     1051    93     0    93    93     0     8    0
ffsino     296     2519    0     1051   114     0   114   114     0     8    0
nchpl      144     3587    0     1894    63     0    63    63     0     8    0
vnodes     216     2600    0        0   145     0   145   145     0     8    0
namei      1024   11781    0    11781     2     0     2     2     0     8    2
percpumem   16       50    0        0     1     0     1     1     0     8    0
kstatmem   264       25    0        0     2     0     2     2     0     8    0
scxspl     216    11979    0    11979     7     5     2     6     1     8    2
plimitpl   152      177    0      151     2     0     2     2     0     8    0
sigapl     424     1052    0      998     7     0     7     7     0     8    0
knotepl    120      330    0        0    10     0    10    10     0     8    0
kqueuepl   224      286    0      210     5     0     5     5     0     8    0
pipepl     344      173    0      146     3     0     3     3     0     8    0
fdescpl    528     1036    0      998     4     0     4     4     0     8    0
filepl     160     6065    0     5705    18     2    16    16     0     8    0
lockfpl    104      224    0      215     1     0     1     1     0     8    0
lockfspl    48       73    0       68     1     0     1     1     0     8    0
sessionpl  144       71    0       54     1     0     1     1     0     8    0
pgrppl      48       87    0       62     1     0     1     1     0     8    0
ucredpl    104     1281    0     1262     1     0     1     1     0     8    0
zombiepl   144     1000    0      998     1     0     1     1     0     8    0
processpl  1232    1052    0      998     5     0     5     5     0     8    0
procpl     664     2141    0     2074     7     0     7     7     0     8    0
sosppl     176        4    0        4     2     1     1     1     0     8    1
sockpl     752     1560    0     1459    13     2    11    11     0     8    0
mcl64k     65536     10    0        0     2     0     2     2     0     8    0
mcl8k      8192       3    0        0     1     0     1     1     0     8    0
mcl4k      4096     127    0        0    16     0    16    16     0     8    0
mcl2k      2048      31    0        0     4     0     4     4     0     8    0
mtagpl      96        3    0        0     1     0     1     1     0     8    0
mbufpl     256      335    0        0    21     0    21    21     0     8    0
bufpl      280     3445    0      102   239     0   239   239     0     8    0
anonpl      32     9621    0        0    78     0    78    78     0   246    0
amapchunkpl 152   28876    0    28245    35     1    34    34     0   158    8
amappl16   200     3760    0     3727    22     8    14    15     0     8    8
amappl15   192        5    0        4     1     0     1     1     0     8    0
amappl14   184      404    0      403     1     0     1     1     0     8    0
amappl13   176      136    0      126     1     0     1     1     0     8    0
amappl12   168     1290    0     1253     2     0     2     2     0     8    0
amappl11   160       19    0       19     1     1     0     1     0     8    0
amappl10   152       62    0       51     1     0     1     1     0     8    0
amappl9    144      260    0      260     1     1     0     1     0     8    0
amappl8    136       99    0       98     1     0     1     1     0     8    0
amappl7    128      156    0      144     1     0     1     1     0     8    0
amappl6    120      177    0      175     1     0     1     1     0     8    0
amappl5    112      127    0      119     1     0     1     1     0     8    0
amappl4    104      300    0      284     1     0     1     1     0     8    0
amappl3     96     5630    0     5483     5     1     4     4     0     8    0
amappl2     88      623    0      568     2     0     2     2     0     8    0
amappl1     80    15667    0    15086    16     0    16    16     0     8    0
amappl      88     8033    0     7823     5     0     5     5     0    92    0
uvmvnodes   80      119    0        0     3     0     3     3     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       95    0        2     2     0     2     2     0     8    0
uaddrrnd    24     1036    0      998     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24     1036    0      998     1     0     1     1     0     8    0
vmmpekpl   168    11375    0    11347     2     0     2     2     0     8    0
vmmpepl    168    79074    0    76921   107     1   106   106     0   357    7
vmsppl     488     1035    0      998     7     2     5     6     0     8    0
rwobjpl     80    25843    0    24742    27     1    26    26     0     8    0
pdppl      4096    2079    0     1996   121    34    87    99     0     8    4
pvpl        32    16246    0        0   132     0   132   132     0   265    0
pmappl     256     1035    0      998     4     1     3     3     0     8    0
extentpl    40       45    0       27     1     0     1     1     0     8    0
phpool     112      311    0       38     8     0     8     8     0     8    0
ddb{0}> machine ddbcpu 0
Invalid cpu 0
ddb{0}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83454ec5) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff8348f2e8,ffffffff834883dd,642,ffffffff833d7ba0) at __assert+0x29 sys/kern/subr_prf.c:-1
process_stop(ffff80003c3e4020,8000000,1) at process_stop+0x3fe
cursig(ffff80003c3dfcb8,ffff80003c41d6f8,0) at cursig+0x509 x86_atomic_setbits_u32 sys/arch/amd64/compile/SYZKALLER/obj/machine/atomic.h:-1 [inline]
cursig(ffff80003c3dfcb8,ffff80003c41d6f8,0) at cursig+0x509 sys/kern/kern_sig.c:1445
userret(ffff80003c3dfcb8) at userret+0x203 sys/kern/kern_sig.c:2207
syscall(ffff80003c41d830) at syscall+0x9ce mi_syscall_return sys/sys/syscall_mi.h:203 [inline]
syscall(ffff80003c41d830) at syscall+0x9ce sys/arch/amd64/amd64/trap.c:804
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x1eedb82c050, count: -8
ddb{0}> machine ddbcpu 1
Stopped at      x86_ipi_db+0x27:        addq    $0x8,%rsp
x86_ipi_db(ffff8000299adff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394
x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27
end of kernel
end trace frame: 0x77b651145b70, count: 12
ddb{1}> trace
x86_ipi_db(ffff8000299adff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394
x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106
Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27
end of kernel
end trace frame: 0x77b651145b70, count: -3

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/30 00:49 openbsd 167506022718 340bcdf0 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-setuid assert "ISSET(p->p_flag, P_SUSPSIG | P_SUSPSINGLE) == NUM" failed in kern_sig.c
* Struck through repros no longer work on HEAD.