panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 944 Stopped at db_enter+0x25: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 406846 27387 0 0 0 1 syz-executor db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8343d8a7) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e808d,ffffffff833f194a,3b0,ffffffff833f1992) at __assert+0x29 refcnt_finalize(ffff80003a4c73c8,ffffffff8332dbac) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003a4c73c0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff8000ffffc530) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c4f7d90) at spec_close+0x412 VOP_CLOSE(fffffd805f9c1630,1,fffffd807f7d27b8,ffff8000ffffc530) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd80601bc300,ffff8000ffffc530) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd80601bc300,ffff8000ffffc530) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd80601bc300,ffff8000ffffc530) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd80601bc300,ffff8000ffffc530) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff8000ffffc530) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff8000ffffc530,0,0,1) at exit1+0x58f sys/kern/kern_exit.c:216 sys_exit(ffff8000ffffc530,ffff80003c4f8100,ffff80003c4f8050) at sys_exit+0x1a end trace frame: 0xffff80003c4f80f0, 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{0}> ddb{0}> set $lines = 0 ddb{0}> set $maxwidth = 0 ddb{0}> show panic *cpu0: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 944 ddb{0}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8343d8a7) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e808d,ffffffff833f194a,3b0,ffffffff833f1992) at __assert+0x29 refcnt_finalize(ffff80003a4c73c8,ffffffff8332dbac) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003a4c73c0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff8000ffffc530) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c4f7d90) at spec_close+0x412 VOP_CLOSE(fffffd805f9c1630,1,fffffd807f7d27b8,ffff8000ffffc530) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd80601bc300,ffff8000ffffc530) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd80601bc300,ffff8000ffffc530) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd80601bc300,ffff8000ffffc530) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd80601bc300,ffff8000ffffc530) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff8000ffffc530) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff8000ffffc530,0,0,1) at exit1+0x58f sys/kern/kern_exit.c:216 sys_exit(ffff8000ffffc530,ffff80003c4f8100,ffff80003c4f8050) at sys_exit+0x1a syscall(ffff80003c4f8100) at syscall+0xb08 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c4f8100) at syscall+0xb08 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x78f84d8d1700, count: -16 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff80003c4f7b60 rbx 0xffffffff837e1dc7 cpu_info_full_primary+0x2dc7 rdx 0 rcx 0xffff8000ffffc530 rax 0xffffffff837e0ff0 cpu_info_full_primary+0x1ff0 r8 0 r9 0x8080808080808080 r10 0x9b8fa483d39d4b5f r11 0xa12467e794034655 r12 0xffffffff837e1bc8 cpu_info_full_primary+0x2bc8 r13 0 r14 0 r15 0x1 rip 0xffffffff818fdc85 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c4f7b50 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor) tid=203957 pid=23530 tcnt=0 stat=onproc flags process=1018 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff8000ffffc530 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff8000ffff47d8,0xffff8000ffff4558 process=0xffff8000ffff0020 user=0xffff80003c4f3000, vmspace=0xfffffd806bdc5740 estcpu=36, cpticks=7, pctcpu=0.0, user=0, sys=1, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 27387 406846 31265 0 7 0 syz-executor 27387 471660 31265 0 3 0x4000080 fsleep syz-executor 27387 433636 31265 0 2 0x4000000 syz-executor 82293 421546 47095 0 2 0 syz-executor 82293 281482 47095 0 3 0x4000080 fsleep syz-executor 79925 165513 92369 0 2 0 syz-executor 79925 25764 92369 0 3 0x4000080 fsleep syz-executor 82380 213584 65056 60929 3 0x90 nanoslp syz-executor 82380 300953 65056 60929 3 0x4000010 smrbar syz-executor 6240 196298 25444 0 2 0 syz-executor 6240 244895 25444 0 3 0x4000080 netacc syz-executor 6240 152951 25444 0 3 0x4000080 fsleep syz-executor 17058 197251 0 0 3 0x14200 bored sosplice 3160 289941 0 0 3 0x14200 acct acct 30939 112167 98141 0 3 0x100082 sbwait arp 98141 25981 5131 0 3 0x10008a sigsusp sh 17370 14825 80499 0 3 0x82 nanoslp syz-executor 31265 425456 80499 0 2 0x482 syz-executor 65056 396254 80499 0 3 0x82 nanoslp syz-executor 16332 131938 80499 0 2 0x482 syz-executor 25444 42529 80499 0 2 0x482 syz-executor 47095 321138 80499 0 2 0x482 syz-executor 92369 386521 80499 0 2 0x482 syz-executor 5131 415162 80499 0 3 0x82 wait syz-executor 80499 499971 24475 0 3 0x82 kqread syz-executor 24475 454765 94521 0 3 0x10008a sigsusp ksh 94521 92784 55148 0 3 0x98 kqread sshd-session 55148 263111 9296 0 3 0x92 kqread sshd-session 89893 31531 1 0 3 0x100083 ttyin getty 9296 46863 1 0 3 0x88 kqread sshd 31064 505394 36160 74 3 0x1100092 bpf pflogd 36160 212305 1 0 3 0x80 sbwait pflogd 9051 276112 21900 73 3 0x1100090 kqread syslogd 21900 184284 1 0 3 0x100082 sbwait syslogd 17338 45361 1 0 3 0x100080 kqread resolvd 53924 331334 88350 77 3 0x100092 kqread dhcpleased 61435 497208 88350 77 3 0x100092 kqread dhcpleased 88350 513201 1 0 3 0x80 kqread dhcpleased 79844 23555 0 0 3 0x14200 bored smr 72615 287529 0 0 2 0x14200 zerothread 4157 264785 0 0 3 0x14200 aiodoned aiodoned 5147 349520 0 0 3 0x14200 syncer update 10610 160020 0 0 3 0x14200 cleaner cleaner 3724 446622 0 0 3 0x14200 reaper reaper 69855 117373 0 0 3 0x14200 pgdaemon pagedaemon 10141 311872 0 0 3 0x14200 bored viomb 12865 423204 0 0 3 0x40014200 acpi0 acpi0 85124 178594 0 0 3 0x40014200 idle1 82213 17242 0 0 3 0x14200 bored softnet3 50111 326693 0 0 3 0x14200 bored softnet2 33604 125098 0 0 3 0x14200 bored softnet1 63472 35053 0 0 3 0x14200 bored softnet0 65019 106271 0 0 3 0x14200 bored systqmp 39486 120058 0 0 3 0x14200 bored systq 96167 231026 0 0 3 0x14200 tmoslp softclockmp 32020 496173 0 0 2 0x40014200 softclock 36734 271969 0 0 3 0x40014200 idle0 1 40819 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}> show all locks ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10201 11031K 11100K 166960K 11421 0 pcb 17 12K 12K 166960K 52 0 rtable 224 6K 7K 166960K 342 0 pf 38 18K 22K 166960K 62 0 ifaddr 43 7K 7K 166960K 47 0 ifgroup 60 2K 2K 166960K 67 0 sysctl 3 1K 1K 166960K 3 0 counters 68 36K 36K 166960K 74 0 ioctlops 0 0K 4K 166960K 1496 0 iov 0 0K 16K 166960K 16 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1335 84K 84K 166960K 1490 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 3 5K 5K 166960K 7 0 VM map 2 1K 1K 166960K 2 0 sem 6 0K 0K 166960K 7 0 dirhash 12 2K 2K 166960K 24 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 19 69K 240K 166960K 327 0 sigio 0 0K 0K 166960K 5 0 proc 72 91K 152K 166960K 556 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 32 0 in_multi 90 6K 6K 166960K 100 0 ether_multi 1 0K 0K 166960K 2 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 73 334K 334K 166960K 73 0 exec 0 0K 1K 166960K 410 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 234 73K 77K 166960K 4482 0 UVM aobj 11 2K 2K 166960K 14 0 pinsyscall 45 90K 104K 166960K 1386 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 10 0 NDP 13 0K 1K 166960K 29 0 temp 45 8636K 8704K 166960K 13056 0 kqueue 15 24K 26K 166960K 60 0 SYN cache 2 16K 16K 166960K 2 0 ddb{0}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle plcache 128 24 0 0 1 0 1 1 0 8 0 rtpcb 120 48 0 43 1 0 1 1 0 8 0 rtentry 112 106 0 2 3 0 3 3 0 8 0 unpcb 144 140 0 118 2 1 1 2 0 8 0 syncache 336 5 0 5 1 1 0 1 0 8 0 tcpcb 808 92 0 86 5 3 2 4 0 8 1 arp 120 17 0 0 1 0 1 1 0 8 0 inpcb 376 245 0 233 5 3 2 5 0 8 0 nd6 136 22 0 0 1 0 1 1 0 8 0 pkpcb 40 2 0 2 1 1 0 1 0 8 0 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1168 3 0 2 2 1 1 1 0 8 0 pppxif 1472 1 0 0 1 0 1 1 0 8 0 pffrag 232 2 0 0 1 0 1 1 0 482 0 pffrnode 88 2 0 0 1 0 1 1 0 8 0 pffrent 40 2 0 0 1 0 1 1 0 8 0 pfosfp 40 1428 0 1005 5 0 5 5 0 8 0 pfosfpen 112 1428 0 714 21 0 21 21 0 8 0 pfanchor 1288 1 0 1 1 1 0 1 0 8 0 pfstitem 24 37 0 0 1 0 1 1 0 8 0 pfstkey 128 37 0 0 2 0 2 2 0 8 0 pfstate 376 36 0 0 4 0 4 4 0 8 0 pfrule 1344 23 0 18 2 1 1 2 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 419 0 0 27 0 27 27 0 8 0 art_table 32 420 0 0 4 0 4 4 0 8 0 art_node 16 104 0 9 1 0 1 1 0 8 0 sysvmsgpl 40 4 0 4 1 0 1 1 0 8 1 semupl 112 2 0 2 1 0 1 1 0 8 1 semapl 112 5 0 1 1 0 1 1 0 8 0 shmpl 112 11 0 3 1 0 1 1 0 8 0 dirhash 1024 25 0 8 3 0 3 3 0 8 0 dino2pl 256 1937 0 428 95 0 95 95 0 8 0 ffsino 280 1937 0 428 109 0 109 109 0 8 0 nchpl 144 2395 0 704 63 0 63 63 0 8 0 uvmvnodes 80 2055 0 0 42 0 42 42 0 8 0 vnodes 216 2055 0 0 115 0 115 115 0 8 0 namei 1024 7840 0 7840 2 1 1 1 0 8 1 percpumem 16 51 0 3 1 0 1 1 0 8 0 kstatmem 264 30 0 4 2 0 2 2 0 8 0 scsiplug 72 1 0 1 1 1 0 1 0 8 0 scxspl 216 7611 0 7611 6 4 2 3 1 8 2 plimitpl 152 88 0 71 1 0 1 1 0 8 0 sigapl 424 609 0 556 7 0 7 7 0 8 0 futexpl 64 2814 0 2810 1 0 1 1 0 8 0 knotepl 120 310 0 0 10 0 10 10 0 8 0 kqueuepl 216 106 0 94 3 2 1 3 0 8 0 pipepl 328 127 0 100 3 0 3 3 0 8 0 fdescpl 504 589 0 556 5 0 5 5 0 8 0 filepl 152 2917 0 2688 12 0 12 12 0 8 2 lockfpl 104 189 0 186 2 0 2 2 0 8 1 lockfspl 48 29 0 26 1 0 1 1 0 8 0 sessionpl 144 24 0 15 1 0 1 1 0 8 0 pgrppl 48 37 0 20 1 0 1 1 0 8 0 ucredpl 104 387 0 370 1 0 1 1 0 8 0 zombiepl 144 558 0 556 1 0 1 1 0 8 0 processpl 1176 609 0 556 5 0 5 5 0 8 0 procpl 656 938 0 878 6 0 6 6 0 8 0 sosppl 168 3 0 3 1 1 0 1 0 8 0 sockpl 688 437 0 398 7 2 5 6 0 8 1 mcl64k 65536 2 0 0 1 0 1 1 0 8 0 mcl16k 16384 1 0 0 1 0 1 1 0 8 0 mcl8k 8192 4 0 0 1 0 1 1 0 8 0 mcl4k 4096 122 0 0 16 0 16 16 0 8 0 mcl2k 2048 24 0 0 3 0 3 3 0 8 0 mtagpl 96 1 0 0 1 0 1 1 0 8 0 mbufpl 256 177 0 0 12 0 12 12 0 8 0 bufpl 280 2694 0 129 184 0 184 184 0 8 0 anonpl 24 123870 0 120266 60 34 26 59 0 184 1 amapchunkpl 152 13980 0 13468 25 3 22 25 0 158 0 amappl16 200 2577 0 2548 15 12 3 14 0 8 0 amappl15 192 5 0 5 1 1 0 1 0 8 0 amappl14 184 112 0 99 1 0 1 1 0 8 0 amappl13 176 10 0 9 1 0 1 1 0 8 0 amappl12 168 1220 0 1186 3 1 2 2 0 8 0 amappl11 160 53 0 39 1 0 1 1 0 8 0 amappl10 152 5 0 5 1 1 0 1 0 8 0 amappl9 144 245 0 245 1 1 0 1 0 8 0 amappl8 136 26 0 23 1 0 1 1 0 8 0 amappl7 128 111 0 98 1 0 1 1 0 8 0 amappl6 120 195 0 191 1 0 1 1 0 8 0 amappl5 112 128 0 117 1 0 1 1 0 8 0 amappl4 104 318 0 298 1 0 1 1 0 8 0 amappl3 96 2448 0 2328 4 0 4 4 0 8 0 amappl2 88 647 0 582 2 0 2 2 0 8 0 amappl1 80 8752 0 8153 14 0 14 14 0 8 0 amappl 88 4092 0 3917 5 0 5 5 0 92 0 dma4096 4096 1 0 1 1 1 0 1 0 8 0 dma1024 1024 1 0 0 1 0 1 1 0 8 0 dma256 256 6 0 6 1 1 0 1 0 8 0 dma128 128 254 0 254 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 18 0 17 1 0 1 1 0 8 0 aobjpl 72 13 0 3 1 0 1 1 0 8 0 uaddrrnd 24 589 0 556 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 589 0 556 1 0 1 1 0 8 0 vmmpekpl 168 6783 0 6751 2 0 2 2 0 8 0 vmmpepl 168 43358 0 41420 95 6 89 95 0 357 3 vmsppl 456 588 0 556 5 0 5 5 0 8 0 rwobjpl 64 17497 0 14456 50 0 50 50 0 8 0 pdppl 4096 1186 0 1112 96 22 74 84 0 8 0 pvpl 32 15859 0 0 129 1 128 128 0 265 0 pmappl 248 588 0 556 3 0 3 3 0 8 0 extentpl 40 55 0 38 1 0 1 1 0 8 0 phpool 112 274 0 30 8 0 8 8 0 8 0 ddb{0}> machine ddbcpu 0 Invalid cpu 0 ddb{0}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8343d8a7) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e808d,ffffffff833f194a,3b0,ffffffff833f1992) at __assert+0x29 refcnt_finalize(ffff80003a4c73c8,ffffffff8332dbac) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(205b9a,ffff80003a4c73c0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff8000ffffc530) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c4f7d90) at spec_close+0x412 VOP_CLOSE(fffffd805f9c1630,1,fffffd807f7d27b8,ffff8000ffffc530) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd80601bc300,ffff8000ffffc530) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd80601bc300,ffff8000ffffc530) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd80601bc300,ffff8000ffffc530) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd80601bc300,ffff8000ffffc530) at closef+0x192 sys/kern/kern_descrip.c:1249 fdfree(ffff8000ffffc530) at fdfree+0x116 sys/kern/kern_descrip.c:1181 exit1(ffff8000ffffc530,0,0,1) at exit1+0x58f sys/kern/kern_exit.c:216 sys_exit(ffff8000ffffc530,ffff80003c4f8100,ffff80003c4f8050) at sys_exit+0x1a syscall(ffff80003c4f8100) at syscall+0xb08 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c4f8100) at syscall+0xb08 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x78f84d8d1700, count: -16 ddb{0}> machine ddbcpu 1 Stopped at x86_ipi_db+0x27: addq $0x8,%rsp x86_ipi_db(ffff800029a9bff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 end of kernel end trace frame: 0x7340543c0b00, count: 12 ddb{1}> trace x86_ipi_db(ffff800029a9bff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 end of kernel end trace frame: 0x7340543c0b00, count: -3