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(ffffffff834807f0) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c274d,ffffffff83523966,3bb,ffffffff834fcf67) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c927758,ffffffff8347af20) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff80003c927750) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a77cfa8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c8f99a0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffff5806b95eea0,41,fffff58007ffd7b8,ffff80002a77cfa8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffff58069d28018,ffff80002a77cfa8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffff58069d28018,ffff80002a77cfa8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffff58069d28018,ffff80002a77cfa8) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffff58069d28018,ffff80002a77cfa8) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80002a77cfa8) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80002a77cfa8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a77cfa8,ffff80003c8f9d00,ffff80003c8f9c50) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff80003c8f9cf0, 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(ffffffff834807f0) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c274d,ffffffff83523966,3bb,ffffffff834fcf67) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c927758,ffffffff8347af20) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff80003c927750) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a77cfa8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c8f99a0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffff5806b95eea0,41,fffff58007ffd7b8,ffff80002a77cfa8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffff58069d28018,ffff80002a77cfa8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffff58069d28018,ffff80002a77cfa8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffff58069d28018,ffff80002a77cfa8) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffff58069d28018,ffff80002a77cfa8) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80002a77cfa8) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80002a77cfa8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a77cfa8,ffff80003c8f9d00,ffff80003c8f9c50) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c8f9d00) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c8f9d00) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ef080f12210, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003c8f9780 rbx 0 rdx 0 rcx 0 rax 0xffff80002a77cfa8 r8 0x101010101010101 r9 0x8080808080808080 r10 0xd5d39416d7e1ad95 r11 0xb2ad4ee2b1b07bd1 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff82b91815 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c8f9770 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=398321 pid=39773 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a77cfa8 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a77c548,0xffff80003c8fb4f0 process=0xffff8000ffffba98 user=0xffff80003c8f4000, vmspace=0xfffff5806cac0460 estcpu=36, cpticks=2, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 65209 104054 42925 0 2 0 syz-executor 88105 520531 35795 0 2 0 syz-executor 88105 320513 35795 0 3 0x4000080 fsleep syz-executor 16871 267032 86130 0 2 0xc80 syz-executor 16871 172409 86130 0 2 0x4000000 syz-executor 16871 43484 86130 0 3 0x4000080 fsleep syz-executor 16871 43697 86130 0 3 0x4000080 fsleep syz-executor 30280 277763 30386 0 2 0xc80 syz-executor 30280 127247 30386 0 3 0x4000080 pipewr syz-executor 30280 478131 30386 0 3 0x4000080 pipewr syz-executor 30280 25662 30386 0 3 0x4000080 fsleep syz-executor 56286 38116 39826 0 2 0x2 syz-executor 25009 307593 39826 0 3 0x82 nanoslp syz-executor 69266 224643 39826 0 2 0xc82 syz-executor 30386 393739 39826 0 2 0xc82 syz-executor 77203 183194 39826 0 3 0x82 nanoslp syz-executor 42925 391172 39826 0 2 0xc82 syz-executor 35795 233005 39826 0 2 0xc82 syz-executor 86130 179051 39826 0 3 0x82 nanoslp syz-executor 39826 89444 30322 0 3 0x82 kqread syz-executor 30322 504284 75608 0 3 0x10008a sigsusp ksh 75608 429090 22563 0 3 0x98 kqread sshd-session 22563 22205 92773 0 3 0x92 kqread sshd-session 49280 220786 1 0 3 0x100083 ttyin getty 92773 27657 1 0 3 0x88 kqread sshd 48751 314302 72409 73 3 0x1100090 kqread syslogd 72409 286129 1 0 3 0x100082 sbwait syslogd 19388 164607 1 0 3 0x100080 kqread resolvd 19641 275120 24950 77 2 0x100012 dhcpleased 51553 199546 24950 77 3 0x100092 kqread dhcpleased 24950 217358 1 0 3 0x80 kqread dhcpleased 19462 100140 0 0 3 0x14200 bored smr 64596 410911 0 0 2 0x14200 zerothread 35088 354815 0 0 3 0x14200 aiodoned aiodoned 86452 432464 0 0 3 0x14200 syncer update 81341 310683 0 0 3 0x14200 cleaner cleaner 90194 359019 0 0 3 0x14200 reaper reaper 77708 7896 0 0 3 0x14200 pgdaemon pagedaemon 31885 110252 0 0 3 0x14200 bored viomb 39416 61334 0 0 3 0x40014200 acpi0 acpi0 23439 481834 0 0 2 0x14200 softnet0 55279 415424 0 0 3 0x14200 smrbar systqmp 13311 154886 0 0 3 0x14200 bored systq 26127 118411 0 0 3 0x40014200 tmoslp softclock 64948 210611 0 0 3 0x40014200 idle0 1 212915 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 11040 12170K 12429K 166960K 12206 0 pcb 20 13K 14K 166960K 89 0 rtable 251 7K 7K 166960K 399 0 pf 35 14K 18K 166960K 60 0 ifaddr 43 7K 8K 166960K 50 0 ifgroup 55 2K 2K 166960K 66 0 sysctl 3 1K 9K 166960K 7 0 counters 35 18K 18K 166960K 40 0 ioctlops 0 0K 4K 166960K 51 0 iov 0 0K 12K 166960K 2 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1301 82K 82K 166960K 1422 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 3 5K 9K 166960K 5 0 VM map 2 1K 1K 166960K 2 0 sem 5 0K 0K 166960K 7 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 17 61K 240K 166960K 226 0 sigio 0 0K 0K 166960K 4 0 proc 60 59K 83K 166960K 504 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 9 0 in_multi 99 7K 7K 166960K 102 0 ether_multi 1 0K 0K 166960K 1 0 mrt 1 0K 0K 166960K 8 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 67 307K 307K 166960K 67 0 exec 0 0K 1K 166960K 369 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 221 159K 167K 166960K 3574 0 UVM aobj 9 2K 2K 166960K 10 0 pinsyscall 38 76K 94K 166960K 1313 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 2 0 NDP 12 0K 2K 166960K 31 0 temp 38 9103K 9150K 166960K 6380 0 kqueue 13 20K 28K 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 41 0 38 1 0 1 1 0 8 0 rtentry 136 125 0 12 4 0 4 4 0 8 0 unpcb 144 83 0 68 1 0 1 1 0 8 0 syncache 336 4 0 4 1 0 1 1 0 8 1 tcpcb 736 28 0 22 1 0 1 1 0 8 0 arp 96 20 0 2 1 0 1 1 0 8 0 ipq 40 2 0 0 1 0 1 1 0 8 0 ipqe 40 3 0 1 1 0 1 1 0 8 0 inpcb 328 157 0 144 4 0 4 4 0 8 2 nd6 112 26 0 0 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 4 0 3 1 0 1 1 0 8 0 pppxif 1416 2 0 1 1 0 1 1 0 8 0 pfstscr 40 5 0 0 1 0 1 1 0 8 0 pfanchor 1288 2 0 2 1 0 1 1 0 8 1 pftag 88 2 0 0 1 0 1 1 0 8 0 pfstitem 24 4 0 1 1 0 1 1 0 8 0 pfstkey 128 4 0 1 1 0 1 1 0 8 0 pfstate 384 3 0 0 1 0 1 1 0 8 0 pfrule 1360 3 0 3 1 0 1 1 0 8 1 rttmr 136 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 256 524 0 43 32 0 32 32 0 8 1 art_table 40 525 0 43 6 0 6 6 0 8 0 art_node 32 125 0 21 1 0 1 1 0 8 0 sysvmsgpl 40 35 0 35 1 0 1 1 0 8 1 semapl 72 5 0 2 1 0 1 1 0 8 0 shmpl 112 7 0 1 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1701 0 236 92 0 92 92 0 8 0 ffsino 256 1701 0 236 92 0 92 92 0 8 0 nchpl 144 2003 0 307 64 0 64 64 0 8 0 vnodes 216 1823 0 0 102 0 102 102 0 8 0 namei 1024 6040 0 6039 2 0 2 2 0 8 1 kstatmem 264 31 0 6 2 0 2 2 0 8 0 scsiplug 72 1 0 1 1 0 1 1 0 8 1 scxspl 216 6841 0 6841 4 0 4 4 1 8 4 plimitpl 152 104 0 86 1 0 1 1 0 8 0 sigapl 424 508 0 466 6 0 6 6 0 8 1 knotepl 120 4831 0 4784 3 0 3 3 0 8 0 kqueuepl 184 43 0 33 1 0 1 1 0 8 0 pipepl 304 128 0 100 3 0 3 3 0 8 0 fdescpl 448 495 0 466 5 0 5 5 0 8 1 filepl 120 1968 0 1748 8 0 8 8 0 8 0 lockfpl 104 35 0 33 1 0 1 1 0 8 0 lockfspl 48 18 0 16 1 0 1 1 0 8 0 sessionpl 144 29 0 21 1 0 1 1 0 8 0 pgrppl 48 37 0 21 1 0 1 1 0 8 0 ucredpl 104 149 0 138 1 0 1 1 0 8 0 zombiepl 144 469 0 466 1 0 1 1 0 8 0 processpl 1152 508 0 466 4 0 4 4 0 8 0 procpl 664 629 0 580 5 0 5 5 0 8 0 sockpl 552 288 0 257 5 0 5 5 0 8 2 mcl64k 65536 3 0 3 1 0 1 1 0 8 1 mcl8k 8192 4 0 4 1 0 1 1 0 8 1 mcl4k 4096 2601 0 2547 13 0 13 13 0 8 6 mcl2k 2048 263 0 263 2 0 2 2 0 8 2 mtagpl 96 6 0 5 1 0 1 1 0 8 0 mbufpl 256 5015 0 4856 12 0 12 12 0 8 0 bufpl 280 2474 0 103 170 0 170 170 0 8 0 anonpl 24 88692 0 85310 31 0 31 31 0 186 9 amapchunkpl 152 10056 0 9597 22 0 22 22 0 158 2 amappl16 200 1286 0 1247 4 0 4 4 0 8 1 amappl15 192 4 0 4 1 0 1 1 0 8 1 amappl14 184 409 0 408 1 0 1 1 0 8 0 amappl13 176 114 0 104 1 0 1 1 0 8 0 amappl12 168 767 0 740 2 0 2 2 0 8 0 amappl11 160 3 0 3 1 0 1 1 0 8 1 amappl10 152 59 0 49 1 0 1 1 0 8 0 amappl9 144 274 0 274 1 0 1 1 0 8 1 amappl8 136 152 0 151 1 0 1 1 0 8 0 amappl7 128 140 0 129 1 0 1 1 0 8 0 amappl6 120 175 0 174 1 0 1 1 0 8 0 amappl5 112 93 0 85 1 0 1 1 0 8 0 amappl4 104 259 0 244 1 0 1 1 0 8 0 amappl3 96 1931 0 1827 3 0 3 3 0 8 0 amappl2 88 515 0 463 2 0 2 2 0 8 0 amappl1 80 10288 0 9741 13 0 13 13 0 8 1 amappl 88 2871 0 2715 4 0 4 4 0 92 0 uvmvnodes 80 98 0 0 2 0 2 2 0 8 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 128 253 0 253 1 0 1 1 0 8 1 dma64 64 7 0 7 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 9 0 1 1 0 1 1 0 8 0 uaddrrnd 24 495 0 466 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 495 0 466 1 0 1 1 0 8 0 vmmpekpl 168 5841 0 5807 2 0 2 2 0 8 0 vmmpepl 168 40172 0 38399 81 0 81 81 0 357 0 vmsppl 368 494 0 466 4 0 4 4 0 8 1 rwobjpl 40 14276 0 13324 11 0 11 11 0 8 1 pdppl 4096 996 0 932 96 28 68 80 0 8 4 pvpl 32 227558 0 218308 92 0 92 92 0 265 12 pmappl 216 494 0 466 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 362 0 28 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(ffffffff834807f0) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c274d,ffffffff83523966,3bb,ffffffff834fcf67) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c927758,ffffffff8347af20) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff80003c927750) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a77cfa8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c8f99a0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffff5806b95eea0,41,fffff58007ffd7b8,ffff80002a77cfa8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffff58069d28018,ffff80002a77cfa8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffff58069d28018,ffff80002a77cfa8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffff58069d28018,ffff80002a77cfa8) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffff58069d28018,ffff80002a77cfa8) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80002a77cfa8) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80002a77cfa8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a77cfa8,ffff80003c8f9d00,ffff80003c8f9c50) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c8f9d00) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c8f9d00) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ef080f12210, 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(ffffffff834807f0) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c274d,ffffffff83523966,3bb,ffffffff834fcf67) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c927758,ffffffff8347af20) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff80003c927750) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a77cfa8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c8f99a0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffff5806b95eea0,41,fffff58007ffd7b8,ffff80002a77cfa8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffff58069d28018,ffff80002a77cfa8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffff58069d28018,ffff80002a77cfa8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffff58069d28018,ffff80002a77cfa8) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffff58069d28018,ffff80002a77cfa8) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80002a77cfa8) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80002a77cfa8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a77cfa8,ffff80003c8f9d00,ffff80003c8f9c50) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c8f9d00) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c8f9d00) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ef080f12210, count: -16