panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 944 Stopped at db_enter+0x25: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff83400125) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833b0ea0,ffffffff832ffd67,3b0,ffffffff833b90ff) at __assert+0x29 refcnt_finalize(ffff80003912b5c8,ffffffff832fb8a4) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003912b5c0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff800039938550) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c98d200) at spec_close+0x412 VOP_CLOSE(fffffd806ba00bd0,1,fffffd807f7d75b0,ffff800039938550) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156 vn_closefile(fffffd805fcbd078,ffff800039938550) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805fcbd078,ffff800039938550) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805fcbd078,ffff800039938550) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd805fcbd078,ffff800039938550) at closef+0x18d sys/kern/kern_descrip.c:1249 fdfree(ffff800039938550) at fdfree+0x115 sys/kern/kern_descrip.c:1181 exit1(ffff800039938550,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff800039938550,ffff80003c98d570,ffff80003c98d4c0) at sys_exit+0x1a end trace frame: 0xffff80003c98d560, count: 0 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 "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 944 ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff83400125) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833b0ea0,ffffffff832ffd67,3b0,ffffffff833b90ff) at __assert+0x29 refcnt_finalize(ffff80003912b5c8,ffffffff832fb8a4) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003912b5c0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff800039938550) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c98d200) at spec_close+0x412 VOP_CLOSE(fffffd806ba00bd0,1,fffffd807f7d75b0,ffff800039938550) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156 vn_closefile(fffffd805fcbd078,ffff800039938550) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805fcbd078,ffff800039938550) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805fcbd078,ffff800039938550) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd805fcbd078,ffff800039938550) at closef+0x18d sys/kern/kern_descrip.c:1249 fdfree(ffff800039938550) at fdfree+0x115 sys/kern/kern_descrip.c:1181 exit1(ffff800039938550,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff800039938550,ffff80003c98d570,ffff80003c98d4c0) at sys_exit+0x1a syscall(ffff80003c98d570) at syscall+0x97e sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x783985a848a0, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003c98cfe0 rbx 0xffffffff81e2b590 pppxclose rdx 0 rcx 0 rax 0xffff800039938550 r8 0 r9 0x8080808080808080 r10 0xc2cae061df9e9f81 r11 0xe9204575474b87f7 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff82ec7405 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c98cfd0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=67476 pid=82733 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=50, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff800039938550 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a812020,0xffff800039938d10 process=0xffff800037125158 user=0xffff80003c988000, vmspace=0xfffffd806befb5b8 estcpu=36, cpticks=3, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 5440 298458 85365 0 2 0 syz-executor 5440 85210 85365 0 3 0x4000080 fsleep syz-executor 8760 472041 72871 0 2 0 syz-executor 8760 71514 72871 0 3 0x4000000 smrbar syz-executor 62417 202760 60047 0 3 0x80 nanoslp syz-executor 62417 129456 60047 0 3 0x4000080 pipewr syz-executor 30374 124912 6257 0 2 0 syz-executor 30374 403488 6257 0 3 0x4000080 fsleep syz-executor 45618 456921 8330 0 3 0x80 nanoslp syz-executor 45618 452042 8330 0 3 0x4000080 lockf syz-executor 45618 122730 8330 0 3 0x4000080 fsleep syz-executor 55055 24901 0 0 3 0x14200 bored sosplice 88578 337888 0 0 3 0x14280 nfsidl nfsio 40316 124392 0 0 3 0x14280 nfsidl nfsio 7319 240891 0 0 3 0x14280 nfsidl nfsio 69229 204274 0 0 3 0x14280 nfsidl nfsio 18618 44166 0 0 3 0x14280 nfsidl nfsio 11099 2324 0 0 3 0x14280 nfsidl nfsio 31105 467578 0 0 3 0x14280 nfsidl nfsio 41135 281246 0 0 3 0x14280 nfsidl nfsio 57316 397824 0 0 3 0x14280 nfsidl nfsio 91938 363543 0 0 3 0x14280 nfsidl nfsio 19903 118873 0 0 3 0x14280 nfsidl nfsio 70452 477785 0 0 3 0x14280 nfsidl nfsio 30465 139419 0 0 3 0x14280 nfsidl nfsio 41082 431814 0 0 3 0x14280 nfsidl nfsio 39299 462290 0 0 3 0x14280 nfsidl nfsio 12801 434192 0 0 3 0x14280 nfsidl nfsio 20259 384043 0 0 3 0x14280 nfsidl nfsio 68636 479055 0 0 3 0x14280 nfsidl nfsio 80160 82081 0 0 3 0x14280 nfsidl nfsio 41392 480383 0 0 3 0x14280 nfsidl nfsio 6257 329657 56824 0 2 0x482 syz-executor 4413 234340 56824 0 3 0x82 nanoslp syz-executor 8330 515850 56824 0 3 0x82 nanoslp syz-executor 35651 395591 56824 0 2 0x482 syz-executor 77042 297325 56824 0 3 0x82 wait syz-executor 72871 18054 56824 0 2 0x482 syz-executor 60047 150921 56824 0 3 0x82 nanoslp syz-executor 85365 388533 56824 0 2 0x482 syz-executor 56824 243630 81767 0 2 0x2 syz-executor 81767 151791 35399 0 3 0x10008a sigsusp ksh 35399 9863 22256 0 3 0x98 kqread sshd-session 22256 344760 70424 0 3 0x92 kqread sshd-session 96377 421220 1 0 3 0x100083 ttyin getty 70424 401541 1 0 3 0x88 kqread sshd 95823 482918 60320 73 3 0x1100090 kqread syslogd 60320 85211 1 0 3 0x100082 sbwait syslogd 64936 229077 1 0 3 0x100080 kqread resolvd 29899 216608 16315 77 3 0x100092 kqread dhcpleased 21862 472378 16315 77 3 0x100092 kqread dhcpleased 16315 53112 1 0 3 0x80 kqread dhcpleased 29136 66447 0 0 3 0x14200 bored smr 56333 488608 0 0 2 0x14200 zerothread 60405 445013 0 0 3 0x14200 aiodoned aiodoned 44353 354376 0 0 3 0x14200 syncer update 85534 192646 0 0 3 0x14200 cleaner cleaner 54242 135505 0 0 3 0x14200 reaper reaper 52045 195363 0 0 3 0x14200 pgdaemon pagedaemon 50259 315237 0 0 3 0x14200 bored viomb 77851 359715 0 0 3 0x40014200 acpi0 acpi0 40812 258064 0 0 3 0x14200 bored softnet3 90461 41362 0 0 3 0x14200 bored softnet2 48529 214970 0 0 3 0x14200 bored softnet1 28024 150916 0 0 3 0x14200 bored softnet0 15875 373949 0 0 3 0x14200 bored systqmp 20733 214546 0 0 3 0x14200 bored systq 82153 162365 0 0 2 0x40014200 softclock 36315 204986 0 0 3 0x40014200 idle0 1 213193 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 10185 11043K 11398K 166960K 12218 0 pcb 19 14K 16K 166960K 200 0 rtable 248 8K 9K 166960K 418 0 pf 35 14K 21K 166960K 67 0 ifaddr 43 7K 7K 166960K 61 0 ifgroup 55 2K 2K 166960K 89 0 sysctl 3 1K 2K 166960K 4 0 counters 32 17K 17K 166960K 47 0 ioctlops 0 0K 4K 166960K 77 0 iov 0 0K 20K 166960K 34 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1437 90K 91K 166960K 1883 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 9K 166960K 11 0 VM map 2 1K 1K 166960K 2 0 sem 28 5K 6K 166960K 33 0 dirhash 12 2K 3K 166960K 27 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 97K 166960K 558 0 sigio 0 0K 0K 166960K 20 0 proc 60 59K 108K 166960K 509 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 58 0 in_multi 99 7K 7K 166960K 122 0 ether_multi 1 0K 0K 166960K 3 0 mrt 1 0K 0K 166960K 2 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 85 387K 387K 166960K 85 0 exec 0 0K 1K 166960K 560 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 220 72K 88K 166960K 6495 0 UVM aobj 15 4K 4K 166960K 15 0 pinsyscall 39 78K 96K 166960K 1586 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 22 0 NDP 12 0K 1K 166960K 39 0 temp 46 8628K 8699K 166960K 25109 0 kqueue 15 24K 28K 166960K 124 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 120 144 0 140 3 0 3 3 0 8 2 rtentry 112 128 0 16 4 0 4 4 0 8 0 unpcb 144 417 0 399 4 0 4 4 0 8 3 syncache 336 3 0 3 1 0 1 1 0 8 1 tcpcb 808 268 0 263 7 0 7 7 0 8 6 arp 88 20 0 2 1 0 1 1 0 8 0 ipq 40 1 0 0 1 0 1 1 0 8 0 ipqe 40 1 0 0 1 0 1 1 0 8 0 inpcb 344 741 0 731 10 1 9 10 0 8 7 nd6 104 27 0 1 1 0 1 1 0 8 0 pkpcb 40 2 0 2 1 0 1 1 0 8 1 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1072 11 0 10 1 0 1 1 0 8 0 pppxif 1376 3 0 2 1 0 1 1 0 8 0 pfrktable 1344 1 0 0 1 0 1 1 0 8 0 pftag 88 1 0 0 1 0 1 1 0 8 0 pfrule 1344 4 0 2 1 0 1 1 0 8 0 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 486 0 28 29 0 29 29 0 8 0 art_table 32 488 0 28 4 0 4 4 0 8 0 art_node 16 125 0 24 1 0 1 1 0 8 0 sysvmsgpl 40 38 0 37 1 0 1 1 0 8 0 semapl 112 27 0 1 1 0 1 1 0 8 0 shmpl 112 12 0 0 1 0 1 1 0 8 0 dirhash 1024 27 0 10 3 0 3 3 0 8 0 dino2pl 256 2398 0 900 95 0 95 95 0 8 0 ffsino 248 2398 0 900 95 0 95 95 0 8 0 nchpl 144 3199 0 1518 63 0 63 63 0 8 0 uvmvnodes 80 2827 0 0 58 0 58 58 0 8 0 vnodes 216 2827 0 0 158 0 158 158 0 8 0 namei 1024 11545 0 11545 2 0 2 2 0 8 2 kstatmem 264 44 0 20 2 0 2 2 0 8 0 scsiplug 72 2 0 2 1 0 1 1 0 8 1 scxspl 216 9823 0 9823 8 0 8 8 1 8 8 plimitpl 152 154 0 138 1 0 1 1 0 8 0 sigapl 424 856 0 789 8 0 8 8 0 8 0 futexpl 64 7145 0 7142 1 0 1 1 0 8 0 knotepl 120 44689 0 44636 16 6 10 16 0 8 8 kqueuepl 184 164 0 151 1 0 1 1 0 8 0 pipepl 296 150 0 121 3 0 3 3 0 8 0 fdescpl 440 818 0 788 5 0 5 5 0 8 1 filepl 120 5203 0 4969 13 0 13 13 0 8 3 lockfpl 104 154 0 149 1 0 1 1 0 8 0 lockfspl 48 66 0 63 1 0 1 1 0 8 0 sessionpl 144 21 0 13 1 0 1 1 0 8 0 pgrppl 48 37 0 21 1 0 1 1 0 8 0 ucredpl 104 762 0 750 1 0 1 1 0 8 0 zombiepl 144 792 0 789 1 0 1 1 0 8 0 processpl 1104 856 0 789 5 0 5 5 0 8 0 procpl 656 1490 0 1417 7 0 7 7 0 8 0 sosppl 168 6 0 6 1 0 1 1 0 8 1 sockpl 528 1312 0 1280 12 0 12 12 0 8 8 mcl64k 65536 9 0 9 1 0 1 1 0 8 1 mcl16k 16384 1 0 1 1 0 1 1 0 8 1 mcl9k 9216 1 0 1 1 0 1 1 0 8 1 mcl8k 8192 77 0 77 1 0 1 1 0 8 1 mcl4k 4096 2954 0 2903 14 0 14 14 0 8 7 mcl2k 2048 687 0 687 4 0 4 4 0 8 4 mtagpl 96 94 0 4 3 0 3 3 0 8 0 mbufpl 256 10179 0 9901 104 0 104 104 0 8 79 bufpl 280 3084 0 127 212 0 212 212 0 8 0 anonpl 24 146711 0 142228 45 0 45 45 0 187 17 amapchunkpl 152 21645 0 21095 33 0 33 33 0 158 11 amappl16 200 3041 0 3000 20 9 11 15 0 8 8 amappl15 192 7 0 7 1 0 1 1 0 8 1 amappl14 184 105 0 95 1 0 1 1 0 8 0 amappl13 176 27 0 26 1 0 1 1 0 8 0 amappl12 168 1463 0 1431 3 0 3 3 0 8 1 amappl11 160 46 0 36 1 0 1 1 0 8 0 amappl10 152 3 0 3 1 0 1 1 0 8 1 amappl9 144 241 0 241 1 0 1 1 0 8 1 amappl8 136 28 0 26 1 0 1 1 0 8 0 amappl7 128 97 0 87 1 0 1 1 0 8 0 amappl6 120 173 0 169 1 0 1 1 0 8 0 amappl5 112 133 0 127 1 0 1 1 0 8 0 amappl4 104 296 0 282 1 0 1 1 0 8 0 amappl3 96 3962 0 3854 4 0 4 4 0 8 0 amappl2 88 627 0 569 2 0 2 2 0 8 0 amappl1 80 8778 0 8259 13 0 13 13 0 8 1 amappl 88 6115 0 5942 5 0 5 5 0 92 0 dma65536 65536 1 0 1 1 0 1 1 0 8 1 dma4096 4096 1 0 1 1 0 1 1 0 8 1 dma1024 1024 1 0 0 1 0 1 1 0 8 0 dma256 256 6 0 6 1 0 1 1 0 8 1 dma128 128 253 0 253 1 0 1 1 0 8 1 dma64 64 6 0 6 1 0 1 1 0 8 1 dma32 32 7 0 7 1 0 1 1 0 8 1 dma16 16 18 0 17 1 0 1 1 0 8 0 aobjpl 72 14 0 0 1 0 1 1 0 8 0 uaddrrnd 24 818 0 788 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 818 0 788 1 0 1 1 0 8 0 vmmpekpl 168 7743 0 7704 3 0 3 3 0 8 0 vmmpepl 168 55408 0 53608 89 0 89 89 0 357 10 vmsppl 360 817 0 788 4 0 4 4 0 8 1 rwobjpl 32 20290 0 16590 31 0 31 31 0 8 1 pdppl 4096 1642 0 1576 98 32 66 82 0 8 0 pvpl 32 378149 0 367801 119 0 119 119 0 265 34 pmappl 216 817 0 788 3 0 3 3 0 8 0 extentpl 40 55 0 38 1 0 1 1 0 8 0 phpool 112 366 0 32 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:437 panic(ffffffff83400125) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833b0ea0,ffffffff832ffd67,3b0,ffffffff833b90ff) at __assert+0x29 refcnt_finalize(ffff80003912b5c8,ffffffff832fb8a4) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003912b5c0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff800039938550) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c98d200) at spec_close+0x412 VOP_CLOSE(fffffd806ba00bd0,1,fffffd807f7d75b0,ffff800039938550) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156 vn_closefile(fffffd805fcbd078,ffff800039938550) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805fcbd078,ffff800039938550) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805fcbd078,ffff800039938550) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd805fcbd078,ffff800039938550) at closef+0x18d sys/kern/kern_descrip.c:1249 fdfree(ffff800039938550) at fdfree+0x115 sys/kern/kern_descrip.c:1181 exit1(ffff800039938550,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff800039938550,ffff80003c98d570,ffff80003c98d4c0) at sys_exit+0x1a syscall(ffff80003c98d570) at syscall+0x97e sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x783985a848a0, count: -16 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff83400125) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833b0ea0,ffffffff832ffd67,3b0,ffffffff833b90ff) at __assert+0x29 refcnt_finalize(ffff80003912b5c8,ffffffff832fb8a4) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003912b5c0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff800039938550) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c98d200) at spec_close+0x412 VOP_CLOSE(fffffd806ba00bd0,1,fffffd807f7d75b0,ffff800039938550) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156 vn_closefile(fffffd805fcbd078,ffff800039938550) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805fcbd078,ffff800039938550) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805fcbd078,ffff800039938550) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd805fcbd078,ffff800039938550) at closef+0x18d sys/kern/kern_descrip.c:1249 fdfree(ffff800039938550) at fdfree+0x115 sys/kern/kern_descrip.c:1181 exit1(ffff800039938550,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214 sys_exit(ffff800039938550,ffff80003c98d570,ffff80003c98d4c0) at sys_exit+0x1a syscall(ffff80003c98d570) at syscall+0x97e sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x783985a848a0, count: -16