panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 953 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(ffffffff83341bfb) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337bb4f,ffffffff833d92e4,3b9,ffffffff833b2f5c) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9bab48,ffffffff833375d3) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c9bab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,2,2000,ffff80002a7f42b8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800038152fa0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd8075b7e968,2,fffffd8007bfb3a8,ffff80002a7f42b8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd80739f12d0,ffff80002a7f42b8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd80739f12d0,ffff80002a7f42b8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd80739f12d0,ffff80002a7f42b8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd80739f12d0,ffff80002a7f42b8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7f42b8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7f42b8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7f42b8,ffff800038153300,ffff800038153250) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff8000381532f0, 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 953 ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83341bfb) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337bb4f,ffffffff833d92e4,3b9,ffffffff833b2f5c) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9bab48,ffffffff833375d3) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c9bab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,2,2000,ffff80002a7f42b8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800038152fa0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd8075b7e968,2,fffffd8007bfb3a8,ffff80002a7f42b8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd80739f12d0,ffff80002a7f42b8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd80739f12d0,ffff80002a7f42b8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd80739f12d0,ffff80002a7f42b8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd80739f12d0,ffff80002a7f42b8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7f42b8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7f42b8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7f42b8,ffff800038153300,ffff800038153250) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800038153300) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800038153300) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x71949cb0fd40, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff800038152d80 rbx 0 rdx 0 rcx 0 rax 0xffff80002a7f42b8 r8 0x101010101010101 r9 0x8080808080808080 r10 0xe0878fe4476f7d0b r11 0xdf1027c1162d18f9 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff82122155 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff800038152d70 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=163194 pid=35586 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=50, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a7f42b8 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a81e7e0,0xffff80002a7f4a90 process=0xffff80002cd2c018 user=0xffff80003814e000, vmspace=0xfffffd807e1775d0 estcpu=36, cpticks=3, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 35056 472271 13550 0 2 0 syz-executor 13686 146214 55833 0 2 0 syz-executor 13686 220496 55833 0 3 0x4000000 smrbar syz-executor 13686 323726 55833 0 3 0x4000080 fsleep syz-executor 13686 48162 55833 0 3 0x4000080 fsleep syz-executor 80055 133420 50760 0 2 0 syz-executor 80055 237080 50760 0 3 0x4000080 bell syz-executor 60465 241729 11375 0 3 0x80 nanoslp syz-executor 60465 10534 11375 0 3 0x4000080 kqsel syz-executor 60465 287965 11375 0 3 0x4000080 fsleep syz-executor 17595 235931 78440 0 2 0 syz-executor 17595 164706 78440 0 3 0x4000080 fsleep syz-executor 52061 172010 92445 0 4 0x82000 syz-executor 52061 277631 92445 0 2 0x4082000 syz-executor 52061 119834 92445 0 3 0x4002000 suspend syz-executor 73161 10761 11529 0 2 0 syz-executor 73161 356091 11529 0 2 0x4000000 syz-executor 73161 420851 11529 0 3 0x4000000 inode syz-executor 50760 18451 25706 0 2 0xc82 syz-executor 55833 122730 25706 0 2 0xc82 syz-executor 28666 362375 25706 0 2 0xc82 syz-executor 13550 448880 25706 0 3 0x82 nanoslp syz-executor 92445 287246 25706 0 3 0x82 nanoslp syz-executor 11529 229195 25706 0 3 0x82 nanoslp syz-executor 11375 333630 25706 0 2 0xc82 syz-executor 78440 480624 25706 0 3 0x82 nanoslp syz-executor 25706 496736 81907 0 3 0x82 kqread syz-executor 81907 92535 73239 0 3 0x10008a sigsusp ksh 73239 252648 47137 0 3 0x98 kqread sshd-session 47137 307100 5009 0 3 0x92 kqread sshd-session 87361 201999 1 0 3 0x100083 ttyin getty 5009 125369 1 0 3 0x88 kqread sshd 88523 25229 11407 73 3 0x1100090 kqread syslogd 11407 500247 1 0 3 0x100082 sbwait syslogd 96697 52076 1 0 3 0x100080 kqread resolvd 70993 13439 92342 77 3 0x100092 kqread dhcpleased 98586 117251 92342 77 3 0x100092 kqread dhcpleased 92342 105160 1 0 3 0x80 kqread dhcpleased 21756 197581 0 0 3 0x14200 bored smr 66110 160206 0 0 2 0x14200 zerothread 12540 510031 0 0 3 0x14200 aiodoned aiodoned 88900 371166 0 0 3 0x14200 syncer update 37048 301235 0 0 3 0x14200 cleaner cleaner 42894 280698 0 0 3 0x14200 reaper reaper 82752 487997 0 0 3 0x14200 pgdaemon pagedaemon 30759 187311 0 0 3 0x14200 bored viomb 59301 233720 0 0 3 0x40014200 acpi0 acpi0 53242 5887 0 0 3 0x14200 bored softnet7 19057 460084 0 0 3 0x14200 bored softnet6 88920 466655 0 0 3 0x14200 bored softnet5 43250 373759 0 0 3 0x14200 bored softnet4 47155 38815 0 0 3 0x14200 bored softnet3 52982 362344 0 0 3 0x14200 bored softnet2 72084 175204 0 0 3 0x14200 bored softnet1 59853 307350 0 0 3 0x14200 bored softnet0 11726 43955 0 0 3 0x14200 bored systqmp 3928 157014 0 0 3 0x14200 bored systq 51071 13774 0 0 3 0x40014200 tmoslp softclock 64530 418387 0 0 3 0x40014200 idle0 1 106630 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 10179 11050K 11114K 166960K 11291 0 pcb 17 14K 16K 166960K 106 0 rtable 197 6K 6K 166960K 276 0 pf 31 13K 16K 166960K 44 0 ifaddr 40 7K 7K 166960K 46 0 ifgroup 51 2K 2K 166960K 55 0 sysctl 1 1K 9K 166960K 5 0 counters 33 17K 17K 166960K 34 0 ioctlops 0 0K 4K 166960K 38 0 iov 0 0K 12K 166960K 5 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1337 84K 84K 166960K 1388 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 5 0K 0K 166960K 5 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 73K 166960K 182 0 proc 60 59K 83K 166960K 481 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 5 0 in_multi 89 6K 7K 166960K 101 0 ether_multi 1 0K 0K 166960K 1 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 61 281K 281K 166960K 61 0 exec 0 0K 1K 166960K 351 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 232 143K 146K 166960K 3174 0 UVM aobj 4 2K 2K 166960K 4 0 pinsyscall 39 78K 84K 166960K 1204 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 1 0 NDP 11 0K 2K 166960K 28 0 temp 35 8630K 8694K 166960K 3815 0 kqueue 14 22K 30K 166960K 32 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 39 0 36 1 0 1 1 0 8 0 rtentry 136 96 0 10 4 0 4 4 0 8 0 unpcb 144 64 0 49 1 0 1 1 0 8 0 syncache 336 3 0 3 1 0 1 1 0 8 1 tcpcb 736 53 0 14 4 0 4 4 0 8 0 arp 88 10 0 1 1 0 1 1 0 8 0 inpcb 328 230 0 187 7 0 7 7 0 8 3 ip6q 72 1 0 0 1 0 1 1 0 8 0 ip6af 40 1 0 0 1 0 1 1 0 8 0 nd6 104 16 0 2 1 0 1 1 0 8 0 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1072 1 0 0 1 0 1 1 0 8 0 pppxif 1384 1 0 0 1 0 1 1 0 8 0 pfanchor 1288 4 0 4 1 0 1 1 0 8 1 pfrule 1344 2 0 2 1 0 1 1 0 8 1 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 442 0 42 28 0 28 28 0 8 2 art_table 40 443 0 42 5 0 5 5 0 8 0 art_node 32 96 0 19 1 0 1 1 0 8 0 semapl 112 3 0 0 1 0 1 1 0 8 0 shmpl 112 1 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1633 0 132 95 0 95 95 0 8 0 ffsino 256 1633 0 132 95 0 95 95 0 8 0 nchpl 144 1883 0 201 63 0 63 63 0 8 0 uvmvnodes 80 1730 0 0 36 0 36 36 0 8 0 vnodes 216 1730 0 0 97 0 97 97 0 8 0 namei 1024 5719 0 5719 1 0 1 1 0 8 1 kstatmem 264 24 0 2 2 0 2 2 0 8 0 scsiplug 72 1 0 1 1 0 1 1 0 8 1 scxspl 216 6612 0 6612 8 0 8 8 1 8 8 plimitpl 152 35 0 18 1 0 1 1 0 8 0 sigapl 424 463 0 413 6 0 6 6 0 8 0 knotepl 120 4496 0 4447 16 0 16 16 0 8 13 kqueuepl 184 36 0 24 1 0 1 1 0 8 0 pipepl 304 102 0 75 3 0 3 3 0 8 0 fdescpl 448 443 0 413 4 0 4 4 0 8 0 filepl 120 1647 0 1397 9 0 9 9 0 8 1 lockfpl 104 15 0 12 1 0 1 1 0 8 0 lockfspl 48 9 0 6 1 0 1 1 0 8 0 sessionpl 144 21 0 13 1 0 1 1 0 8 0 pgrppl 48 29 0 13 1 0 1 1 0 8 0 ucredpl 104 109 0 98 1 0 1 1 0 8 0 zombiepl 144 414 0 413 1 0 1 1 0 8 0 processpl 1152 463 0 413 4 0 4 4 0 8 0 procpl 664 541 0 480 6 0 6 6 0 8 0 sockpl 552 333 0 272 7 0 7 7 0 8 2 mcl64k 65536 4 0 4 1 0 1 1 0 8 1 mcl8k 8192 4 0 4 1 0 1 1 0 8 1 mcl4k 4096 2482 0 2431 14 0 14 14 0 8 7 mcl2k 2048 232 0 231 1 0 1 1 0 8 0 mtagpl 96 4 0 4 1 0 1 1 0 8 1 mbufpl 256 4259 0 4127 14 0 14 14 0 8 4 bufpl 280 2921 0 117 201 0 201 201 0 8 0 anonpl 24 101109 0 97801 23 0 23 23 0 187 2 amapchunkpl 152 9353 0 8851 22 0 22 22 0 158 1 amappl16 200 1915 0 1881 5 0 5 5 0 8 3 amappl15 192 5 0 5 1 0 1 1 0 8 1 amappl14 184 107 0 97 1 0 1 1 0 8 0 amappl13 176 2 0 2 1 0 1 1 0 8 1 amappl12 168 1050 0 1020 2 0 2 2 0 8 0 amappl11 160 59 0 49 1 0 1 1 0 8 0 amappl10 152 5 0 5 1 0 1 1 0 8 1 amappl9 144 248 0 248 1 0 1 1 0 8 1 amappl8 136 23 0 22 1 0 1 1 0 8 0 amappl7 128 102 0 92 1 0 1 1 0 8 0 amappl6 120 173 0 170 1 0 1 1 0 8 0 amappl5 112 115 0 109 1 0 1 1 0 8 0 amappl4 104 265 0 251 1 0 1 1 0 8 0 amappl3 96 1474 0 1362 4 0 4 4 0 8 1 amappl2 88 609 0 555 2 0 2 2 0 8 0 amappl1 80 7974 0 7420 12 0 12 12 0 8 0 amappl 88 2541 0 2371 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 dma512 512 1 0 1 1 0 1 1 0 8 1 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 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 3 0 0 1 0 1 1 0 8 0 uaddrrnd 24 443 0 413 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 443 0 413 1 0 1 1 0 8 0 vmmpekpl 168 5054 0 5026 2 0 2 2 0 8 0 vmmpepl 168 34640 0 32770 83 0 83 83 0 357 0 vmsppl 368 442 0 413 3 0 3 3 0 8 0 rwobjpl 40 14096 0 11510 27 0 27 27 0 8 0 pdppl 4096 892 0 826 84 18 66 70 0 8 0 pvpl 32 220873 0 212317 74 0 74 74 0 265 1 pmappl 216 442 0 413 2 0 2 2 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 354 0 18 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(ffffffff83341bfb) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337bb4f,ffffffff833d92e4,3b9,ffffffff833b2f5c) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9bab48,ffffffff833375d3) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c9bab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,2,2000,ffff80002a7f42b8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800038152fa0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd8075b7e968,2,fffffd8007bfb3a8,ffff80002a7f42b8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd80739f12d0,ffff80002a7f42b8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd80739f12d0,ffff80002a7f42b8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd80739f12d0,ffff80002a7f42b8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd80739f12d0,ffff80002a7f42b8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7f42b8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7f42b8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7f42b8,ffff800038153300,ffff800038153250) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800038153300) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800038153300) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x71949cb0fd40, 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(ffffffff83341bfb) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337bb4f,ffffffff833d92e4,3b9,ffffffff833b2f5c) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9bab48,ffffffff833375d3) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c9bab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,2,2000,ffff80002a7f42b8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800038152fa0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd8075b7e968,2,fffffd8007bfb3a8,ffff80002a7f42b8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd80739f12d0,ffff80002a7f42b8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd80739f12d0,ffff80002a7f42b8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd80739f12d0,ffff80002a7f42b8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd80739f12d0,ffff80002a7f42b8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7f42b8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7f42b8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7f42b8,ffff800038153300,ffff800038153250) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800038153300) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800038153300) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x71949cb0fd40, count: -16