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(ffffffff83377ca4) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833b51f8,ffffffff83417d66,3bb,ffffffff833f187d) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff8000fffef0b0,ffffffff8336eff6) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff8000fffef0a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a7bc2b0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000314f7740) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c5b9630,41,fffffd8007bfd8f0,ffff80002a7bc2b0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806ffca8f8,ffff80002a7bc2b0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806ffca8f8,ffff80002a7bc2b0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806ffca8f8,ffff80002a7bc2b0) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806ffca8f8,ffff80002a7bc2b0) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7bc2b0) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7bc2b0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7bc2b0,ffff8000314f7aa0,ffff8000314f79f0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff8000314f7a90, 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(ffffffff83377ca4) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833b51f8,ffffffff83417d66,3bb,ffffffff833f187d) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff8000fffef0b0,ffffffff8336eff6) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff8000fffef0a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a7bc2b0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000314f7740) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c5b9630,41,fffffd8007bfd8f0,ffff80002a7bc2b0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806ffca8f8,ffff80002a7bc2b0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806ffca8f8,ffff80002a7bc2b0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806ffca8f8,ffff80002a7bc2b0) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806ffca8f8,ffff80002a7bc2b0) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7bc2b0) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7bc2b0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7bc2b0,ffff8000314f7aa0,ffff8000314f79f0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff8000314f7aa0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff8000314f7aa0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7608b9ea20b0, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff8000314f7520 rbx 0 rdx 0 rcx 0 rax 0xffff80002a7bc2b0 r8 0x101010101010101 r9 0x8080808080808080 r10 0x6105ecb060599d40 r11 0x7b9e2d7f544586b6 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff821cd935 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff8000314f7510 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=469922 pid=32373 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a7bc2b0 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80003950b4e8,0xffff80002a7bca88 process=0xffff8000ffff9f98 user=0xffff8000314f2000, vmspace=0xfffffd806cb0e2f8 estcpu=36, cpticks=4, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 40611 198033 73268 0 2 0 syz-executor 40611 380345 73268 0 3 0x4000080 kqsel syz-executor 21050 38648 49276 0 3 0x80 nanoslp syz-executor 21050 236301 49276 0 2 0x4000000 syz-executor 30096 289018 37268 0 2 0x82000 syz-executor 30096 390959 37268 0 3 0x4002000 suspend syz-executor 30096 408584 37268 0 4 0x4082000 syz-executor 30096 140049 37268 0 4 0x4082000 syz-executor 56192 326004 28476 0 3 0x80 nanoslp syz-executor 56192 143891 28476 0 3 0x4000080 kqsel syz-executor 56192 403546 28476 0 3 0x4000080 fsleep syz-executor 57408 326411 21978 0 2 0 syz-executor 57408 420450 21978 0 3 0x4000080 lockf syz-executor 57408 511960 21978 0 3 0x4000080 lockf syz-executor 4719 245169 73610 0 3 0x80 nanoslp syz-executor 4719 156866 73610 0 3 0x4000080 ttyout syz-executor 4719 85928 73610 0 3 0x4000080 ttyout syz-executor 4719 36398 73610 0 3 0x4000080 fsleep syz-executor 56480 262581 80780 0 2 0 syz-executor 56480 331949 80780 0 3 0x4000080 fsleep syz-executor 43417 166118 0 0 3 0x14200 acct acct 28476 447898 34288 0 2 0xc82 syz-executor 13406 388493 34288 0 2 0xc82 syz-executor 37268 116732 34288 0 3 0x82 nanoslp syz-executor 21978 226250 34288 0 3 0x82 nanoslp syz-executor 80780 399113 34288 0 3 0x82 nanoslp syz-executor 73610 299637 34288 0 2 0xc82 syz-executor 73268 378953 34288 0 2 0xc82 syz-executor 49276 219056 34288 0 3 0x82 nanoslp syz-executor 34288 220729 40832 0 3 0x82 kqread syz-executor 40832 289314 38631 0 3 0x10008a sigsusp ksh 38631 84482 56715 0 3 0x98 kqread sshd-session 56715 450884 32759 0 3 0x92 kqread sshd-session 87428 496681 1 0 3 0x100083 ttyopn getty 32759 413869 1 0 3 0x88 kqread sshd 60715 28067 13704 73 3 0x1100090 kqread syslogd 13704 231642 1 0 3 0x100082 sbwait syslogd 15729 430245 1 0 3 0x100080 kqread resolvd 78231 224227 62691 77 2 0x100012 dhcpleased 11692 331398 62691 77 3 0x100092 kqread dhcpleased 62691 283324 1 0 3 0x80 kqread dhcpleased 86346 273986 0 0 3 0x14200 bored smr 23409 128174 0 0 2 0x14200 zerothread 71598 136786 0 0 3 0x14200 aiodoned aiodoned 3409 280082 0 0 3 0x14200 syncer update 91007 484406 0 0 3 0x14200 cleaner cleaner 61736 325377 0 0 3 0x14200 reaper reaper 74457 334736 0 0 3 0x14200 pgdaemon pagedaemon 73830 257688 0 0 3 0x14200 bored viomb 50430 91964 0 0 3 0x40014200 acpi0 acpi0 19076 156195 0 0 2 0x14200 softnet0 53345 80152 0 0 3 0x14200 smrbar systqmp 51792 83336 0 0 3 0x14200 bored systq 26597 419503 0 0 3 0x40014200 tmoslp softclock 11132 522012 0 0 3 0x40014200 idle0 1 216262 0 0 3 0x82 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 11039 12135K 12627K 166960K 12420 0 pcb 17 14K 16K 166960K 162 0 rtable 266 10K 11K 166960K 449 0 pf 31 13K 17K 166960K 56 0 ifaddr 44 8K 8K 166960K 61 0 ifgroup 50 2K 2K 166960K 76 0 sysctl 2 1K 9K 166960K 8 0 counters 34 17K 18K 166960K 50 0 ioctlops 0 0K 4K 166960K 97 0 iov 0 0K 20K 166960K 21 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1382 87K 87K 166960K 1574 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 5K 166960K 13 0 VM map 2 1K 1K 166960K 2 0 sem 6 0K 0K 166960K 7 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 89K 166960K 433 0 sigio 1 0K 0K 166960K 3 0 proc 60 59K 75K 166960K 507 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 2 0K 0K 166960K 76 0 in_multi 107 7K 8K 166960K 134 0 ether_multi 1 0K 0K 166960K 9 0 mrt 0 0K 0K 166960K 9 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 389 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 247 148K 158K 166960K 5367 0 UVM aobj 17 6K 6K 166960K 18 0 pinsyscall 39 78K 92K 166960K 1501 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 2 0K 0K 166960K 19 0 NDP 11 0K 2K 166960K 36 0 temp 44 8668K 8923K 166960K 5290 0 kqueue 15 24K 33K 166960K 77 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 120 125 0 121 3 0 3 3 0 8 2 rtentry 136 127 0 20 4 0 4 4 0 8 0 unpcb 144 329 0 313 6 0 6 6 0 8 5 syncache 336 4 0 4 1 0 1 1 0 8 1 tcpqe 32 2 0 2 1 0 1 1 0 8 1 tcpcb 736 101 0 93 2 0 2 2 0 8 1 arp 96 21 0 0 1 0 1 1 0 8 0 inpcb 328 494 0 480 7 0 7 7 0 8 5 ip6q 72 2 0 1 1 0 1 1 0 8 0 ip6af 40 3 0 2 1 0 1 1 0 8 0 nd6 112 27 0 1 1 0 1 1 0 8 0 pkpcb 40 1 0 1 1 0 1 1 0 8 1 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1072 14 0 13 1 0 1 1 0 8 0 pppxif 1384 2 0 1 1 0 1 1 0 8 0 pfanchor 1288 1 0 1 1 0 1 1 0 8 1 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 1360 1 0 1 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 256 540 0 67 31 0 31 31 0 8 1 art_table 40 542 0 67 5 0 5 5 0 8 0 art_node 32 126 0 29 1 0 1 1 0 8 0 sysvmsgpl 40 1 0 1 1 0 1 1 0 8 1 semapl 112 5 0 1 1 0 1 1 0 8 0 shmpl 112 12 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 2102 0 593 95 0 95 95 0 8 0 ffsino 256 2102 0 593 95 0 95 95 0 8 0 nchpl 144 2732 0 1037 63 0 63 63 0 8 0 rtmask 32 2 0 2 1 0 1 1 0 8 1 vnodes 216 2309 0 0 129 0 129 129 0 8 0 namei 1024 8466 0 8466 1 0 1 1 0 8 1 vcpupl 3904 2 0 0 1 0 1 1 0 8 0 vmpool 808 3 0 1 1 0 1 1 0 8 0 kstatmem 264 40 0 18 2 0 2 2 0 8 0 scsiplug 72 3 0 3 1 0 1 1 0 8 1 scxspl 216 8510 0 8510 8 0 8 8 1 8 8 plimitpl 152 132 0 116 1 0 1 1 0 8 0 sigapl 424 724 0 680 6 0 6 6 0 8 1 knotepl 120 17241 0 17189 16 6 10 16 0 8 8 kqueuepl 184 150 0 133 3 0 3 3 0 8 2 pipepl 304 132 0 105 3 0 3 3 0 8 0 fdescpl 448 706 0 676 5 0 5 5 0 8 1 filepl 120 3777 0 3553 11 0 11 11 0 8 4 lockfpl 104 107 0 101 1 0 1 1 0 8 0 lockfspl 48 46 0 42 1 0 1 1 0 8 0 sessionpl 144 21 0 13 1 0 1 1 0 8 0 pgrppl 48 30 0 14 1 0 1 1 0 8 0 ucredpl 104 343 0 332 1 0 1 1 0 8 0 zombiepl 144 681 0 680 1 0 1 1 0 8 0 processpl 1152 724 0 680 4 0 4 4 0 8 0 procpl 664 1180 0 1123 6 0 6 6 0 8 0 sosppl 176 1 0 1 1 0 1 1 0 8 1 sockpl 552 969 0 935 12 0 12 12 0 8 8 mcl64k 65536 21 0 21 1 0 1 1 0 8 1 mcl16k 16384 1 0 1 1 0 1 1 0 8 1 mcl12k 12288 1 0 1 1 0 1 1 0 8 1 mcl8k 8192 9 0 9 1 0 1 1 0 8 1 mcl4k 4096 2846 0 2793 16 1 15 16 0 8 8 mcl2k2 2112 1 0 1 1 0 1 1 0 8 1 mcl2k 2048 456 0 453 2 0 2 2 0 8 1 mtagpl 96 8 0 4 1 0 1 1 0 8 0 mbufpl 256 7518 0 7350 16 0 16 16 0 8 4 bufpl 280 2678 0 119 183 0 183 183 0 8 0 anonpl 24 101570 0 94258 45 0 45 45 0 187 0 amapchunkpl 152 16429 0 15654 32 0 32 32 0 158 1 amappl16 200 1147 0 1116 4 0 4 4 0 8 2 amappl15 192 2 0 2 1 0 1 1 0 8 1 amappl14 184 6 0 5 1 0 1 1 0 8 0 amappl13 176 401 0 400 1 0 1 1 0 8 0 amappl12 168 1040 0 1001 2 0 2 2 0 8 0 amappl11 160 32 0 31 1 0 1 1 0 8 0 amappl10 152 79 0 69 1 0 1 1 0 8 0 amappl9 144 258 0 258 1 0 1 1 0 8 1 amappl8 136 44 0 43 1 0 1 1 0 8 0 amappl7 128 76 0 75 1 0 1 1 0 8 0 amappl6 120 257 0 246 1 0 1 1 0 8 0 amappl5 112 66 0 59 1 0 1 1 0 8 0 amappl4 104 372 0 349 1 0 1 1 0 8 0 amappl3 96 2835 0 2737 3 0 3 3 0 8 0 amappl2 88 827 0 754 2 0 2 2 0 8 0 amappl1 80 9930 0 9388 12 0 12 12 0 8 0 amappl 88 4624 0 4445 5 0 5 5 0 92 0 uvmvnodes 80 105 0 0 3 0 3 3 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 128 255 0 255 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 17 0 1 1 0 1 1 0 8 0 uaddrrnd 24 706 0 676 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 706 0 676 1 0 1 1 0 8 0 vmmpekpl 168 6951 0 6926 2 0 2 2 0 8 0 vmmpepl 168 50118 0 48270 81 0 81 81 0 357 0 vmsppl 368 705 0 676 4 0 4 4 0 8 1 rwobjpl 40 14951 0 13972 10 0 10 10 0 8 0 pdppl 4096 1424 0 1356 97 29 68 78 0 8 0 pvpl 32 293071 0 279030 114 0 114 114 0 265 0 pmappl 216 708 0 677 2 0 2 2 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 378 0 30 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(ffffffff83377ca4) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833b51f8,ffffffff83417d66,3bb,ffffffff833f187d) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff8000fffef0b0,ffffffff8336eff6) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff8000fffef0a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a7bc2b0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000314f7740) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c5b9630,41,fffffd8007bfd8f0,ffff80002a7bc2b0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806ffca8f8,ffff80002a7bc2b0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806ffca8f8,ffff80002a7bc2b0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806ffca8f8,ffff80002a7bc2b0) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806ffca8f8,ffff80002a7bc2b0) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7bc2b0) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7bc2b0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7bc2b0,ffff8000314f7aa0,ffff8000314f79f0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff8000314f7aa0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff8000314f7aa0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7608b9ea20b0, 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(ffffffff83377ca4) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833b51f8,ffffffff83417d66,3bb,ffffffff833f187d) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff8000fffef0b0,ffffffff8336eff6) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff8000fffef0a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff80002a7bc2b0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000314f7740) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c5b9630,41,fffffd8007bfd8f0,ffff80002a7bc2b0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806ffca8f8,ffff80002a7bc2b0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806ffca8f8,ffff80002a7bc2b0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806ffca8f8,ffff80002a7bc2b0) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806ffca8f8,ffff80002a7bc2b0) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7bc2b0) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7bc2b0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7bc2b0,ffff8000314f7aa0,ffff8000314f79f0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff8000314f7aa0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff8000314f7aa0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7608b9ea20b0, count: -16