panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 955 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(ffffffff8337b3d0) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833ba87a,ffffffff8341d9d6,3bb,ffffffff833f7638) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80002a8165e8,ffffffff83375508) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80002a8165e0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a85e7f8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000315031e0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806cd41440,41,fffffd8007bfd9c0,ffff80002a85e7f8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806a50f788,ffff80002a85e7f8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806a50f788,ffff80002a85e7f8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806a50f788,ffff80002a85e7f8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806a50f788,ffff80002a85e7f8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a85e7f8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a85e7f8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a85e7f8,ffff800031503540,ffff800031503490) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff800031503530, 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 955 ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8337b3d0) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833ba87a,ffffffff8341d9d6,3bb,ffffffff833f7638) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80002a8165e8,ffffffff83375508) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80002a8165e0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a85e7f8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000315031e0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806cd41440,41,fffffd8007bfd9c0,ffff80002a85e7f8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806a50f788,ffff80002a85e7f8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806a50f788,ffff80002a85e7f8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806a50f788,ffff80002a85e7f8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806a50f788,ffff80002a85e7f8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a85e7f8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a85e7f8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a85e7f8,ffff800031503540,ffff800031503490) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800031503540) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800031503540) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x75da4bf93cb0, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff800031502fc0 rbx 0 rdx 0 rcx 0 rax 0xffff80002a85e7f8 r8 0x101010101010101 r9 0x8080808080808080 r10 0xeeb8e278f4616442 r11 0x5e47977e111d2ed3 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff81d1ca85 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff800031502fb0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=181317 pid=97905 tcnt=0 stat=onproc flags process=1018 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a85e7f8 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a85e030,0xffff80002f0f3260 process=0xffff8000335644a0 user=0xffff8000314fe000, vmspace=0xfffffd806f5cb178 estcpu=36, cpticks=13, pctcpu=0.0, user=0, sys=2, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 23517 266395 39 0 2 0 syz-executor 23517 339513 39 0 3 0x4000000 smrbar syz-executor 23517 493699 39 0 2 0x4000000 syz-executor 60294 156649 32716 0 2 0 syz-executor 36173 260440 5388 0 2 0 syz-executor 36173 290119 5388 0 2 0x4000000 syz-executor 27509 107874 83612 0 2 0 syz-executor 27509 139515 83612 0 3 0x4000080 netacc syz-executor 27509 391693 83612 0 3 0x4000080 netacc syz-executor 27509 87290 83612 0 2 0x4000000 syz-executor 8255 397798 0 0 3 0x14280 nfsidl nfsio 46461 38765 0 0 3 0x14280 nfsidl nfsio 7546 11225 0 0 3 0x14280 nfsidl nfsio 91393 378573 0 0 3 0x14280 nfsidl nfsio 42859 509889 1 0 3 0x100083 ttyin getty 5388 93659 55997 0 2 0x3 syz-executor 18772 189048 55997 0 2 0x2 syz-executor 83612 391343 55997 0 3 0x82 nanoslp syz-executor 39 340735 55997 0 3 0x82 nanoslp syz-executor 8372 211498 58132 0 3 0x82 sbwait sshd-session 96694 361495 55997 0 3 0x82 nanoslp syz-executor 7775 432748 55997 0 3 0x82 wait syz-executor 32716 357004 55997 0 2 0x3 syz-executor 33944 308611 55997 0 2 0x3 syz-executor 55997 464604 21344 0 3 0x82 kqread syz-executor 21344 98214 33460 0 3 0x10008a sigsusp ksh 33460 193369 94653 0 3 0x98 kqread sshd-session 94653 139972 58132 0 3 0x92 kqread sshd-session 58132 52708 1 0 3 0x88 kqread sshd 94520 328360 17959 73 3 0x1100090 kqread syslogd 17959 395897 1 0 3 0x100082 sbwait syslogd 60759 9736 1 0 3 0x100080 kqread resolvd 24649 211805 21580 77 3 0x100092 kqread dhcpleased 15668 473937 21580 77 3 0x100092 kqread dhcpleased 21580 225085 1 0 3 0x80 kqread dhcpleased 19429 9387 0 0 3 0x14200 bored smr 10388 268394 0 0 2 0x14200 zerothread 50602 156285 0 0 3 0x14200 aiodoned aiodoned 30904 48446 0 0 3 0x14200 syncer update 8370 221105 0 0 3 0x14200 cleaner cleaner 30283 522909 0 0 2 0x14200 reaper 2295 451041 0 0 3 0x14200 pgdaemon pagedaemon 42558 114154 0 0 3 0x14200 bored viomb 99204 324412 0 0 3 0x40014200 acpi0 acpi0 77935 192633 0 0 3 0x14200 bored softnet0 4100 5398 0 0 3 0x14200 bored systqmp 52275 455032 0 0 3 0x14200 bored systq 48522 469847 0 0 3 0x40014200 tmoslp softclock 76413 122461 0 0 3 0x40014200 idle0 1 189345 0 0 3 0x80082 wait init 0 0 -1 0 3 0x10010200 scheduler swapper ddb> show all locks No such command ddb> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10209 11057K 11703K 166960K 13697 0 pcb 17 16K 17K 166960K 520 0 rtable 182 7K 9K 166960K 690 0 pf 35 14K 17K 166960K 169 0 ifaddr 35 5K 8K 166960K 133 0 ifgroup 55 2K 2K 166960K 220 0 sysctl 3 1K 9K 166960K 13 0 counters 36 18K 18K 166960K 209 0 ioctlops 0 0K 4K 166960K 427 0 iov 0 0K 20K 166960K 145 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1462 92K 93K 166960K 2736 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 3 5K 9K 166960K 22 0 VM map 2 1K 1K 166960K 2 0 sem 12 0K 1K 166960K 120 0 dirhash 12 2K 2K 166960K 42 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 109K 166960K 1450 0 sigio 0 0K 0K 166960K 106 0 proc 60 59K 83K 166960K 752 0 subproc 72 4K 4K 166960K 117 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 287 0 in_multi 66 4K 7K 166960K 208 0 ether_multi 1 0K 0K 166960K 12 0 mrt 0 0K 0K 166960K 15 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 247 1102K 1102K 166960K 247 0 exec 0 0K 1K 166960K 584 0 fusefs mount 1 32K 32K 166960K 1 0 pfkey data 0 0K 0K 166960K 1 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 242 169K 193K 166960K 14426 0 UVM aobj 134 12K 12K 166960K 137 0 pinsyscall 41 82K 86K 166960K 2703 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 107 0 NDP 12 0K 2K 166960K 90 0 temp 81 8672K 8924K 166960K 70338 0 kqueue 14 22K 32K 166960K 230 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 120 292 0 289 5 2 3 3 0 8 2 rtentry 136 218 0 146 4 0 4 4 0 8 0 unpcb 144 1114 0 1094 6 5 1 6 0 8 0 syncache 336 15 0 15 2 1 1 1 0 8 1 tcpqe 32 7 0 7 2 1 1 1 0 8 1 tcpcb 736 661 0 646 11 6 5 7 0 8 3 arp 96 31 0 20 1 0 1 1 0 8 0 ipq 40 6 0 2 1 0 1 1 0 8 0 ipqe 40 7 0 3 1 0 1 1 0 8 0 inpcb 328 1810 0 1792 18 10 8 12 0 8 6 ip6q 72 8 0 5 1 0 1 1 0 8 0 ip6af 40 14 0 11 1 0 1 1 0 8 0 nd6 112 52 0 32 1 0 1 1 0 8 0 pkpcb 40 9 0 9 2 1 1 1 0 8 1 kcovpl 48 13 0 5 1 0 1 1 0 8 0 mppekey 1024 3 0 3 1 1 0 1 0 8 0 ppxss 1072 150 0 148 2 1 1 1 0 8 0 pppxif 1384 45 0 43 2 1 1 1 0 8 0 pfrktable 1344 2 0 2 2 1 1 1 0 8 1 pfrule 1344 9 0 8 1 0 1 1 0 8 0 rttmr 136 3 0 3 2 1 1 1 0 8 1 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 997 0 639 32 1 31 31 0 8 5 art_table 40 999 0 639 5 0 5 5 0 8 0 art_node 32 213 0 150 1 0 1 1 0 8 0 sysvmsgpl 40 3 0 1 1 0 1 1 0 8 0 semupl 112 2 0 2 1 1 0 1 0 8 0 semapl 112 115 0 105 1 0 1 1 0 8 0 shmpl 112 131 0 3 4 0 4 4 0 8 0 dirhash 1024 39 0 22 3 0 3 3 0 8 0 dino2pl 256 4077 0 2574 95 0 95 95 0 8 0 ffsino 256 4077 0 2574 95 0 95 95 0 8 0 nchpl 144 6073 0 4367 64 0 64 64 0 8 0 rtmask 32 5 0 5 2 1 1 1 0 8 1 vnodes 216 4944 0 0 275 0 275 275 0 8 0 namei 1024 22080 0 22080 3 2 1 2 0 8 1 vcpupl 3904 3 0 0 1 0 1 1 0 8 0 vmpool 800 3 0 0 1 0 1 1 0 8 0 kstatmem 264 126 0 102 2 0 2 2 0 8 0 acpiwqpl 32 1 0 1 1 0 1 1 1 8 1 scsiplug 72 7 0 7 2 1 1 1 0 8 1 scxspl 216 21374 0 21374 9 7 2 8 1 8 2 plimitpl 152 646 0 630 1 0 1 1 0 8 0 sigapl 424 1758 0 1710 8 2 6 8 0 8 0 knotepl 120 62621 0 62565 28 17 11 22 0 8 8 kqueuepl 184 734 0 721 7 3 4 4 0 8 3 pipepl 304 369 0 342 8 5 3 8 0 8 0 fdescpl 448 1719 0 1688 4 0 4 4 0 8 0 filepl 120 12578 0 12354 15 4 11 13 0 8 1 lockfpl 104 591 0 589 2 1 1 2 0 8 0 lockfspl 48 237 0 235 1 0 1 1 0 8 0 sessionpl 144 38 0 29 1 0 1 1 0 8 0 pgrppl 48 131 0 114 1 0 1 1 0 8 0 ucredpl 104 1852 0 1839 1 0 1 1 0 8 0 zombiepl 144 2024 0 2020 2 1 1 1 0 8 0 processpl 1152 1758 0 1710 5 0 5 5 0 8 0 procpl 664 3707 0 3649 7 1 6 7 0 8 0 sosppl 176 8 0 8 1 1 0 1 0 8 0 sockpl 552 3265 0 3224 19 11 8 13 0 8 4 mcl64k 65536 147 0 146 2 1 1 1 0 8 0 mcl16k 16384 7 0 7 2 1 1 1 0 8 1 mcl12k 12288 5 0 5 2 1 1 1 0 8 1 mcl9k 9216 3 0 3 1 1 0 1 0 8 0 mcl8k 8192 16 0 16 2 1 1 1 0 8 1 mcl4k 4096 4199 0 4140 14 5 9 14 0 8 1 mcl2k2 2112 2 0 2 1 0 1 1 0 8 1 mcl2k 2048 2280 0 2276 6 3 3 4 0 8 2 mtagpl 96 33 0 25 1 0 1 1 0 8 0 mbufpl 256 19139 0 18993 14 0 14 14 0 8 1 bufpl 280 6658 0 437 445 0 445 445 0 8 0 anonpl 24 255558 0 252218 56 10 46 46 0 187 11 amapchunkpl 152 50138 0 49648 46 19 27 40 0 158 5 amappl16 200 4145 0 4108 17 3 14 15 0 8 8 amappl15 192 98 0 98 1 1 0 1 0 8 0 amappl14 184 103 0 103 2 1 1 1 0 8 1 amappl13 176 466 0 465 1 0 1 1 0 8 0 amappl12 168 2172 0 2132 2 0 2 2 0 8 0 amappl11 160 93 0 93 1 1 0 1 0 8 0 amappl10 152 45 0 35 1 0 1 1 0 8 0 amappl9 144 254 0 254 1 1 0 1 0 8 0 amappl8 136 23 0 22 1 0 1 1 0 8 0 amappl7 128 100 0 99 1 0 1 1 0 8 0 amappl6 120 334 0 322 1 0 1 1 0 8 0 amappl5 112 86 0 77 1 0 1 1 0 8 0 amappl4 104 462 0 438 1 0 1 1 0 8 0 amappl3 96 9801 0 9693 4 0 4 4 0 8 0 amappl2 88 666 0 604 2 0 2 2 0 8 0 amappl1 80 17467 0 16848 16 1 15 15 0 8 0 amappl 88 13321 0 13158 5 0 5 5 0 92 0 uvmvnodes 80 138 0 0 3 0 3 3 0 8 0 dma4096 4096 1 0 1 1 1 0 1 0 8 0 dma1024 1024 3 0 2 1 0 1 1 0 8 0 dma512 512 1 0 1 1 1 0 1 0 8 0 dma256 256 7 0 7 2 1 1 1 0 8 1 dma128 128 257 0 257 2 1 1 1 0 8 1 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 19 0 18 1 0 1 1 0 8 0 aobjpl 72 136 0 3 3 0 3 3 0 8 0 uaddrrnd 24 1719 0 1688 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 1719 0 1688 1 0 1 1 0 8 0 vmmpekpl 168 15486 0 15432 3 0 3 3 0 8 0 vmmpepl 168 116667 0 114717 105 7 98 98 0 357 9 vmsppl 368 1718 0 1688 3 0 3 3 0 8 0 rwobjpl 40 32061 0 30844 15 0 15 15 0 8 0 pdppl 4096 3450 0 3379 107 36 71 73 0 8 0 pvpl 32 744299 0 734969 136 19 117 117 0 265 21 pmappl 216 1721 0 1688 2 0 2 2 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 403 0 61 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(ffffffff8337b3d0) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833ba87a,ffffffff8341d9d6,3bb,ffffffff833f7638) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80002a8165e8,ffffffff83375508) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80002a8165e0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a85e7f8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000315031e0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806cd41440,41,fffffd8007bfd9c0,ffff80002a85e7f8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806a50f788,ffff80002a85e7f8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806a50f788,ffff80002a85e7f8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806a50f788,ffff80002a85e7f8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806a50f788,ffff80002a85e7f8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a85e7f8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a85e7f8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a85e7f8,ffff800031503540,ffff800031503490) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800031503540) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800031503540) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x75da4bf93cb0, 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(ffffffff8337b3d0) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833ba87a,ffffffff8341d9d6,3bb,ffffffff833f7638) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80002a8165e8,ffffffff83375508) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80002a8165e0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a85e7f8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000315031e0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806cd41440,41,fffffd8007bfd9c0,ffff80002a85e7f8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806a50f788,ffff80002a85e7f8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806a50f788,ffff80002a85e7f8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806a50f788,ffff80002a85e7f8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806a50f788,ffff80002a85e7f8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a85e7f8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a85e7f8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a85e7f8,ffff800031503540,ffff800031503490) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800031503540) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800031503540) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x75da4bf93cb0, count: -16