panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 951 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:438 panic(ffffffff83339344) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337ac54,ffffffff833d7f15,3b7,ffffffff833b1c32) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9be5e0,ffffffff83330bee) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80003c9be5d8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002f132558) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003a56b700) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd80616680e0,1,fffffd8007bfb750,ffff80002f132558) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806bea6100,ffff80002f132558) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806bea6100,ffff80002f132558) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806bea6100,ffff80002f132558) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806bea6100,ffff80002f132558) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002f132558) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002f132558,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002f132558,ffff80003a56ba60,ffff80003a56b9b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff80003a56ba50, 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 951 ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83339344) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337ac54,ffffffff833d7f15,3b7,ffffffff833b1c32) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9be5e0,ffffffff83330bee) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80003c9be5d8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002f132558) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003a56b700) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd80616680e0,1,fffffd8007bfb750,ffff80002f132558) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806bea6100,ffff80002f132558) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806bea6100,ffff80002f132558) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806bea6100,ffff80002f132558) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806bea6100,ffff80002f132558) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002f132558) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002f132558,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002f132558,ffff80003a56ba60,ffff80003a56b9b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003a56ba60) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003a56ba60) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x74923a5cbf80, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003a56b4e0 rbx 0 rdx 0 rcx 0 rax 0xffff80002f132558 r8 0x101010101010101 r9 0x8080808080808080 r10 0xa089640c678134dc r11 0xd96cfdb653ece095 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff827c0405 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003a56b4d0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=259410 pid=43261 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002f132558 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a822018,0xffff80002a7f9cb8 process=0xffff80002d12edc8 user=0xffff80003a566000, vmspace=0xfffffd806ba508b0 estcpu=36, cpticks=4, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 26477 231093 70544 0 2 0xc80 syz-executor 26477 113017 70544 0 3 0x4000000 smrbar syz-executor 26477 176779 70544 0 3 0x4000080 fsleep syz-executor 7357 126178 78238 0 2 0 syz-executor 7357 121853 78238 0 3 0x4000080 fsleep syz-executor 7357 398618 78238 0 3 0x4000080 fsleep syz-executor 85598 30121 76699 0 3 0x80 nanoslp syz-executor 85598 348502 76699 0 3 0x4000080 kqread syz-executor 85598 492666 76699 0 3 0x4000080 kqread syz-executor 15712 260128 88871 0 3 0x80 nanoslp syz-executor 15712 2148 88871 0 3 0x4000080 fsleep syz-executor 15712 316463 88871 0 3 0x4000080 fsleep syz-executor 15712 270705 88871 0 3 0x4000080 fsleep syz-executor 15712 344965 88871 0 3 0x4000080 piperd syz-executor 15712 12868 88871 0 3 0x4000080 fsleep syz-executor 57704 442952 76708 0 2 0x2 syz-executor 31958 134843 1 0 3 0x80 nanoslp init 54613 111171 0 0 3 0x14200 bored sosplice 52731 51532 0 0 3 0x14200 acct acct 68872 344096 76708 0 2 0xc82 syz-executor 78238 442253 76708 0 3 0x82 nanoslp syz-executor 76699 40357 76708 0 3 0x82 nanoslp syz-executor 14492 519057 76708 0 2 0x2 syz-executor 70544 3107 76708 0 3 0x82 nanoslp syz-executor 94449 329614 76708 0 2 0x2 syz-executor 88871 416420 76708 0 2 0xc82 syz-executor 76708 14953 89373 0 3 0x82 kqread syz-executor 89373 369687 2091 0 3 0x10008a sigsusp ksh 2091 166070 4782 0 3 0x98 kqread sshd-session 4782 457155 46151 0 3 0x92 kqread sshd-session 46151 193023 1 0 3 0x88 kqread sshd 96377 5537 80740 73 3 0x1100090 kqread syslogd 80740 47921 1 0 3 0x100082 sbwait syslogd 23550 43396 1 0 3 0x100080 kqread resolvd 50251 119819 53074 77 3 0x100092 kqread dhcpleased 25587 196892 53074 77 3 0x100092 kqread dhcpleased 53074 33578 1 0 3 0x80 kqread dhcpleased 24421 58763 0 0 3 0x14200 bored smr 69951 154018 0 0 2 0x14200 zerothread 13959 49832 0 0 3 0x14200 aiodoned aiodoned 48756 310373 0 0 3 0x14200 syncer update 87907 461872 0 0 3 0x14200 cleaner cleaner 55782 110854 0 0 3 0x14200 reaper reaper 62146 4432 0 0 3 0x14200 pgdaemon pagedaemon 19427 95384 0 0 3 0x14200 bored viomb 29127 517744 0 0 3 0x40014200 acpi0 acpi0 57220 68789 0 0 3 0x14200 bored softnet7 85997 290132 0 0 3 0x14200 bored softnet6 22120 245214 0 0 3 0x14200 bored softnet5 32002 262370 0 0 3 0x14200 bored softnet4 18793 430430 0 0 3 0x14200 bored softnet3 25123 72268 0 0 3 0x14200 bored softnet2 57847 392525 0 0 3 0x14200 bored softnet1 27432 456899 0 0 3 0x14200 bored softnet0 14463 47150 0 0 3 0x14200 bored systqmp 18860 183878 0 0 3 0x14200 bored systq 19410 297144 0 0 2 0x40014200 softclock 55491 65476 0 0 3 0x40014200 idle0 1 372277 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 10192 11178K 11432K 166960K 11810 0 pcb 20 13K 14K 166960K 142 0 rtable 164 5K 7K 166960K 392 0 pf 35 14K 17K 166960K 66 0 ifaddr 39 6K 7K 166960K 67 0 ifgroup 53 2K 2K 166960K 90 0 sysctl 4 1K 9K 166960K 11 0 counters 35 18K 18K 166960K 50 0 ioctlops 0 0K 4K 166960K 223 0 iov 0 0K 16K 166960K 23 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1443 91K 91K 166960K 1809 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 12 0K 0K 166960K 37 0 dirhash 12 2K 2K 166960K 18 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 15 53K 97K 166960K 497 0 sigio 0 0K 0K 166960K 9 0 proc 51 50K 124K 166960K 556 0 subproc 72 4K 4K 166960K 81 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 78 0 in_multi 81 5K 7K 166960K 129 0 ether_multi 1 0K 0K 166960K 4 0 mrt 0 0K 0K 166960K 3 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 55 254K 254K 166960K 55 0 exec 0 0K 2K 166960K 502 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 156K 172K 166960K 5891 0 UVM aobj 20 2K 2K 166960K 21 0 pinsyscall 35 70K 96K 166960K 1550 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 16 0 NDP 12 0K 2K 166960K 41 0 temp 78 8640K 8704K 166960K 17250 0 kqueue 16 26K 30K 166960K 75 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 120 130 0 124 3 0 3 3 0 8 2 rtentry 136 117 0 49 4 0 4 4 0 8 0 unpcb 144 325 0 306 4 0 4 4 0 8 3 syncache 336 3 0 3 1 0 1 1 0 8 1 tcpcb 736 77 0 72 1 0 1 1 0 8 0 arp 88 11 0 3 1 0 1 1 0 8 0 ipq 40 1 0 0 1 0 1 1 0 8 0 ipqe 40 2 0 1 1 0 1 1 0 8 0 inpcb 328 450 0 439 4 0 4 4 0 8 3 ip6q 72 2 0 0 1 0 1 1 0 8 0 ip6af 40 2 0 0 1 0 1 1 0 8 0 nd6 104 22 0 9 1 0 1 1 0 8 0 pkpcb 40 69 0 69 1 0 1 1 0 8 1 kcovpl 48 9 0 1 1 0 1 1 0 8 0 ppxss 1072 12 0 9 1 0 1 1 0 8 0 pppxif 1384 3 0 1 1 0 1 1 0 8 0 pfstscr 40 1 0 1 1 0 1 1 0 8 1 pfosfp 40 2 0 0 1 0 1 1 0 8 0 pfosfpen 112 2 0 0 1 0 1 1 0 8 0 pftag 88 1 0 0 1 0 1 1 0 8 0 pfstitem 24 2 0 0 1 0 1 1 0 8 0 pfstkey 128 4 0 2 1 0 1 1 0 8 0 pfstate 384 2 0 1 1 0 1 1 0 8 0 pfrule 1344 3 0 3 1 0 1 1 0 8 1 rttmr 136 1 0 1 1 0 1 1 0 8 1 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 594 0 272 30 1 29 30 0 8 8 art_table 40 596 0 272 5 0 5 5 0 8 0 art_node 32 116 0 56 1 0 1 1 0 8 0 sysvmsgpl 40 3 0 3 1 0 1 1 0 8 1 semupl 112 1 0 1 1 0 1 1 0 8 1 semapl 112 34 0 24 1 0 1 1 0 8 0 shmpl 112 18 0 1 1 0 1 1 0 8 0 dirhash 1024 21 0 4 3 0 3 3 0 8 0 dino2pl 256 2190 0 687 95 0 95 95 0 8 0 ffsino 256 2190 0 687 95 0 95 95 0 8 0 nchpl 144 2894 0 1206 63 0 63 63 0 8 0 rtmask 32 2 0 2 1 0 1 1 0 8 1 uvmvnodes 80 2614 0 0 54 0 54 54 0 8 0 vnodes 216 2614 0 0 146 0 146 146 0 8 0 namei 1024 9676 0 9674 2 0 2 2 0 8 1 kstatmem 264 46 0 22 2 0 2 2 0 8 0 acpiwqpl 32 1 0 1 1 0 1 1 1 8 1 scsiplug 72 3 0 3 1 0 1 1 0 8 1 scxspl 216 12973 0 12973 8 0 8 8 1 8 8 plimitpl 152 135 0 119 1 0 1 1 0 8 0 sigapl 424 780 0 731 7 0 7 7 0 8 1 knotepl 120 17266 0 17215 10 0 10 10 0 8 7 kqueuepl 184 139 0 126 1 0 1 1 0 8 0 pipepl 304 139 0 110 3 0 3 3 0 8 0 fdescpl 448 758 0 731 5 0 5 5 0 8 1 filepl 120 4157 0 3924 12 0 12 12 0 8 4 lockfpl 104 256 0 252 2 0 2 2 0 8 1 lockfspl 48 121 0 117 1 0 1 1 0 8 0 sessionpl 144 23 0 16 1 0 1 1 0 8 0 pgrppl 48 165 0 150 1 0 1 1 0 8 0 ucredpl 104 371 0 360 1 0 1 1 0 8 0 zombiepl 144 732 0 731 1 0 1 1 0 8 0 processpl 1168 780 0 731 5 0 5 5 0 8 1 procpl 664 1332 0 1272 6 0 6 6 0 8 0 sosppl 168 3 0 3 1 0 1 1 0 8 1 sockpl 552 981 0 945 10 0 10 10 0 8 6 mcl64k 65536 154 0 154 1 0 1 1 0 8 1 mcl12k 12288 1 0 1 1 0 1 1 0 8 1 mcl8k 8192 109 0 109 2 0 2 2 0 8 2 mcl4k 4096 2940 0 2889 14 0 14 14 0 8 7 mcl2k 2048 925 0 921 7 0 7 7 0 8 6 mtagpl 96 9 0 5 1 0 1 1 0 8 0 mbufpl 256 9116 0 8976 16 0 16 16 0 8 4 bufpl 280 5100 0 120 356 0 356 356 0 8 0 anonpl 24 127434 0 122657 57 0 57 57 0 187 23 amapchunkpl 152 18778 0 18325 28 0 28 28 0 158 7 amappl16 200 1997 0 1855 15 2 13 15 0 8 5 amappl15 192 4 0 4 1 0 1 1 0 8 1 amappl14 184 106 0 97 1 0 1 1 0 8 0 amappl13 176 2 0 2 1 0 1 1 0 8 1 amappl12 168 1392 0 1366 3 0 3 3 0 8 1 amappl11 160 63 0 53 1 0 1 1 0 8 0 amappl10 152 5 0 5 1 0 1 1 0 8 1 amappl9 144 258 0 258 1 0 1 1 0 8 1 amappl8 136 18 0 16 1 0 1 1 0 8 0 amappl7 128 95 0 86 1 0 1 1 0 8 0 amappl6 120 182 0 178 1 0 1 1 0 8 0 amappl5 112 118 0 110 1 0 1 1 0 8 0 amappl4 104 265 0 248 1 0 1 1 0 8 0 amappl3 96 3544 0 3445 4 0 4 4 0 8 1 amappl2 88 620 0 566 2 0 2 2 0 8 0 amappl1 80 9426 0 8914 13 0 13 13 0 8 1 amappl 88 5172 0 5015 5 0 5 5 0 92 0 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 128 254 0 254 1 0 1 1 0 8 1 dma64 64 7 0 7 1 0 1 1 0 8 1 dma32 32 8 0 8 1 0 1 1 0 8 1 dma16 16 18 0 17 1 0 1 1 0 8 0 aobjpl 72 20 0 1 1 0 1 1 0 8 0 uaddrrnd 24 758 0 731 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 758 0 731 1 0 1 1 0 8 0 vmmpekpl 168 7160 0 7126 2 0 2 2 0 8 0 vmmpepl 168 52651 0 50821 95 0 95 95 0 357 8 vmsppl 368 757 0 731 4 0 4 4 0 8 1 rwobjpl 40 18365 0 14812 37 0 37 37 0 8 0 pdppl 4096 1522 0 1462 100 34 66 82 0 8 6 pvpl 32 334242 0 323801 133 0 133 133 0 265 40 pmappl 216 757 0 731 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 386 0 35 11 0 11 11 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(ffffffff83339344) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337ac54,ffffffff833d7f15,3b7,ffffffff833b1c32) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9be5e0,ffffffff83330bee) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80003c9be5d8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002f132558) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003a56b700) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd80616680e0,1,fffffd8007bfb750,ffff80002f132558) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806bea6100,ffff80002f132558) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806bea6100,ffff80002f132558) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806bea6100,ffff80002f132558) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806bea6100,ffff80002f132558) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002f132558) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002f132558,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002f132558,ffff80003a56ba60,ffff80003a56b9b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003a56ba60) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003a56ba60) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x74923a5cbf80, count: -16 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83339344) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337ac54,ffffffff833d7f15,3b7,ffffffff833b1c32) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9be5e0,ffffffff83330bee) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80003c9be5d8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002f132558) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003a56b700) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd80616680e0,1,fffffd8007bfb750,ffff80002f132558) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806bea6100,ffff80002f132558) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806bea6100,ffff80002f132558) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806bea6100,ffff80002f132558) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806bea6100,ffff80002f132558) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002f132558) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002f132558,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002f132558,ffff80003a56ba60,ffff80003a56b9b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003a56ba60) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003a56ba60) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x74923a5cbf80, count: -16