panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 951 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(ffffffff83434486) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833e3589,ffffffff83330725,3b7,ffffffff833e8da0) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80002a8b1b10,ffffffff8333358c) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80002a8b1b08) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002a7c2538) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c9793d0) at spec_close+0x412 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c1ff7f0,1,fffffd8007bfb618,ffff80002a7c2538) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156 vn_closefile(fffffd8069c97b50,ffff80002a7c2538) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8069c97b50,ffff80002a7c2538) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8069c97b50,ffff80002a7c2538) at fdrop+0x126 sys/kern/kern_descrip.c:1267 closef(fffffd8069c97b50,ffff80002a7c2538) at closef+0x18d sys/kern/kern_descrip.c:1251 fdfree(ffff80002a7c2538) at fdfree+0x115 sys/kern/kern_descrip.c:1182 exit1(ffff80002a7c2538,0,0,1) at exit1+0x59c sys/kern/kern_exit.c:215 sys_exit(ffff80002a7c2538,ffff80003c979740,ffff80003c979690) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff80003c979730, 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 951 ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83434486) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833e3589,ffffffff83330725,3b7,ffffffff833e8da0) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80002a8b1b10,ffffffff8333358c) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80002a8b1b08) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002a7c2538) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c9793d0) at spec_close+0x412 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c1ff7f0,1,fffffd8007bfb618,ffff80002a7c2538) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156 vn_closefile(fffffd8069c97b50,ffff80002a7c2538) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8069c97b50,ffff80002a7c2538) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8069c97b50,ffff80002a7c2538) at fdrop+0x126 sys/kern/kern_descrip.c:1267 closef(fffffd8069c97b50,ffff80002a7c2538) at closef+0x18d sys/kern/kern_descrip.c:1251 fdfree(ffff80002a7c2538) at fdfree+0x115 sys/kern/kern_descrip.c:1182 exit1(ffff80002a7c2538,0,0,1) at exit1+0x59c sys/kern/kern_exit.c:215 sys_exit(ffff80002a7c2538,ffff80003c979740,ffff80003c979690) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c979740) at syscall+0x97e mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c979740) at syscall+0x97e sys/arch/amd64/amd64/trap.c:742 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72be53a7a0b0, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003c9791b0 rbx 0xffffffff83053d20 pppxclose rdx 0 rcx 0 rax 0xffff80002a7c2538 r8 0 r9 0x8080808080808080 r10 0x4f509afda388ab9b r11 0x647c0e1321902d6e r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff81037fc5 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c9791a0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=150081 pid=61812 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a7c2538 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a7c2ce8,0xffff80002a7c2f88 process=0xffff800036515238 user=0xffff80003c974000, vmspace=0xfffffd806c28d2e0 estcpu=36, cpticks=7, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 26339 342990 45490 0 2 0 syz-executor 26339 475941 45490 0 3 0x4000080 fsleep syz-executor 6508 193905 79332 0 2 0 syz-executor 6508 193986 79332 0 2 0x4000000 syz-executor 6508 512414 79332 0 3 0x4000000 inode syz-executor 62401 494587 0 0 3 0x14200 acct acct 18568 39540 58241 0 2 0 syz-executor 18568 112223 58241 0 3 0x4000000 smrbar syz-executor 18568 163299 58241 0 2 0x4000000 syz-executor 31348 424575 58679 0 2 0 syz-executor 31348 207334 58679 0 3 0x4000080 kqsel syz-executor 39118 300620 94059 60928 3 0x90 nanoslp syz-executor 39118 502995 94059 60928 3 0x4000090 sbwait syz-executor 39118 222972 94059 60928 3 0x4000090 fsleep syz-executor 39118 413956 94059 60928 3 0x4000090 fsleep syz-executor 95909 64752 0 0 3 0x14200 bored sosplice 74154 450643 86371 0 2 0xc82 syz-executor 79332 13053 86371 0 3 0x82 nanoslp syz-executor 94059 446435 86371 0 3 0x82 nanoslp syz-executor 58241 301335 86371 0 3 0x82 nanoslp syz-executor 96347 364862 86371 0 3 0x82 wait syz-executor 84746 123501 86371 0 3 0x82 nanoslp syz-executor 58679 476140 86371 0 2 0xc82 syz-executor 45490 192813 86371 0 3 0x82 nanoslp syz-executor 86371 58392 20628 0 3 0x82 kqread syz-executor 20628 513141 64517 0 3 0x10008a sigsusp ksh 64517 185016 89885 0 3 0x98 kqread sshd-session 89885 63245 21749 0 3 0x92 kqread sshd-session 97815 76706 1 0 3 0x100083 ttyopn getty 21749 45848 1 0 3 0x88 kqread sshd 3461 225542 42658 73 3 0x1100090 kqread syslogd 42658 79429 1 0 3 0x100082 sbwait syslogd 10272 387944 1 0 3 0x100080 kqread resolvd 9674 336057 67914 77 3 0x100092 kqread dhcpleased 71380 176936 67914 77 3 0x100092 kqread dhcpleased 67914 164693 1 0 3 0x80 kqread dhcpleased 19101 337790 0 0 3 0x14200 bored smr 18240 464661 0 0 2 0x14200 zerothread 75537 97916 0 0 3 0x14200 aiodoned aiodoned 63023 88495 0 0 3 0x14200 syncer update 22026 319490 0 0 3 0x14200 cleaner cleaner 97361 473737 0 0 2 0x14200 reaper 50046 51998 0 0 3 0x14200 pgdaemon pagedaemon 91822 22123 0 0 3 0x14200 bored viomb 58095 331063 0 0 3 0x40014200 acpi0 acpi0 22479 207809 0 0 3 0x14200 bored softnet3 33487 111316 0 0 3 0x14200 bored softnet2 71721 154283 0 0 3 0x14200 bored softnet1 68436 215058 0 0 3 0x14200 bored softnet0 37863 254006 0 0 3 0x14200 bored systqmp 33137 282686 0 0 3 0x14200 bored systq 103 254067 0 0 2 0x40014200 softclock 83559 132496 0 0 3 0x40014200 idle0 1 279045 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 10366 11801K 11801K 166960K 12360 0 pcb 51 16K 20K 166960K 261 0 rtable 251 10K 10K 166960K 564 0 pf 40 14K 15K 166960K 80 0 ifaddr 47 8K 8K 166960K 75 0 ifgroup 65 2K 2K 166960K 106 0 sysctl 2 1K 9K 166960K 6 0 counters 38 18K 18K 166960K 58 0 ioctlops 0 0K 4K 166960K 208 0 iov 0 0K 12K 166960K 69 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1395 88K 88K 166960K 1868 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 9K 166960K 13 0 VM map 2 1K 1K 166960K 2 0 sem 12 0K 0K 166960K 116 0 dirhash 12 2K 3K 166960K 24 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 97K 166960K 594 0 sigio 0 0K 0K 166960K 12 0 proc 60 59K 124K 166960K 549 0 subproc 72 4K 4K 166960K 82 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 123 0 in_multi 100 7K 7K 166960K 127 0 ether_multi 1 0K 0K 166960K 2 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 85 387K 387K 166960K 85 0 exec 0 0K 1K 166960K 431 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 236 142K 147K 166960K 6987 0 UVM aobj 21 2K 4K 166960K 25 0 pinsyscall 39 78K 96K 166960K 1657 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 94 0 NDP 15 0K 2K 166960K 46 0 temp 50 8676K 8740K 166960K 22983 0 kqueue 16 23K 28K 166960K 96 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 120 145 0 108 3 1 2 2 0 8 0 rtentry 136 145 0 40 4 0 4 4 0 8 0 unpcb 144 441 0 423 4 1 3 3 0 8 2 syncache 336 4 0 4 2 1 1 1 0 8 1 tcpqe 32 1 0 1 1 0 1 1 0 8 1 tcpcb 736 239 0 233 10 3 7 7 0 8 6 arp 88 22 0 3 1 0 1 1 0 8 0 ipq 40 1 0 0 1 0 1 1 0 8 0 ipqe 40 1 0 0 1 0 1 1 0 8 0 inpcb 328 760 0 717 18 9 9 12 0 8 5 ip6q 72 3 0 1 2 1 1 1 0 8 0 ip6af 40 4 0 2 2 1 1 1 0 8 0 nd6 104 29 0 3 1 0 1 1 0 8 0 pkpcb 40 1 0 1 1 1 0 1 0 8 0 kcovpl 48 9 0 1 1 0 1 1 0 8 0 ppxss 1072 17 0 14 2 1 1 1 0 8 0 pppxif 1384 5 0 3 1 0 1 1 0 8 0 pfosfp 40 35 0 33 1 0 1 1 0 8 0 pfosfpen 112 35 0 32 1 0 1 1 0 8 0 pfrktable 1344 1 0 1 1 1 0 1 0 8 0 pftag 88 1 0 0 1 0 1 1 0 8 0 pfstitem 24 2 0 0 1 0 1 1 0 8 0 pfstkey 128 2 0 0 1 0 1 1 0 8 0 pfstate 384 1 0 0 1 0 1 1 0 8 0 pfrule 1344 2 0 2 1 0 1 1 0 8 1 rttmr 136 2 0 2 2 1 1 1 0 8 1 art_heap8 4096 4 0 0 4 0 4 4 0 8 0 art_heap4 256 625 0 166 30 1 29 29 0 8 0 art_table 32 629 0 166 4 0 4 4 0 8 0 art_node 16 141 0 47 1 0 1 1 0 8 0 sysvmsgpl 40 4 0 0 1 0 1 1 0 8 0 semapl 112 114 0 104 1 0 1 1 0 8 0 shmpl 112 22 0 4 1 0 1 1 0 8 0 dirhash 1024 25 0 8 3 0 3 3 0 8 0 dino2pl 256 2437 0 938 95 0 95 95 0 8 0 ffsino 248 2437 0 938 95 0 95 95 0 8 0 nchpl 144 3256 0 1567 63 0 63 63 0 8 0 rtmask 32 2 0 2 1 0 1 1 0 8 1 uvmvnodes 80 2829 0 0 58 0 58 58 0 8 0 vnodes 216 2829 0 0 158 0 158 158 0 8 0 namei 1024 10664 0 10662 3 2 1 2 0 8 0 kstatmem 264 56 0 26 2 0 2 2 0 8 0 scsiplug 72 1 0 1 1 1 0 1 0 8 0 scxspl 216 12124 0 12124 9 7 2 8 1 8 2 plimitpl 152 233 0 216 1 0 1 1 0 8 0 sigapl 424 895 0 847 9 1 8 8 0 8 2 knotepl 120 27751 0 27700 18 7 11 11 0 8 7 kqueuepl 184 174 0 160 1 0 1 1 0 8 0 pipepl 296 148 0 121 3 0 3 3 0 8 0 fdescpl 440 857 0 827 5 1 4 5 0 8 0 filepl 120 4938 0 4547 13 1 12 12 0 8 0 lockfpl 104 224 0 220 1 0 1 1 0 8 0 lockfspl 48 102 0 98 1 0 1 1 0 8 0 sessionpl 144 23 0 15 1 0 1 1 0 8 0 pgrppl 48 45 0 29 1 0 1 1 0 8 0 ucredpl 104 691 0 679 1 0 1 1 0 8 0 zombiepl 144 1051 0 1048 1 0 1 1 0 8 0 processpl 1160 895 0 847 5 0 5 5 0 8 1 procpl 656 1683 0 1624 7 0 7 7 0 8 1 sosppl 168 6 0 6 2 1 1 1 0 8 1 sockpl 528 1425 0 1327 16 5 11 12 0 8 4 mcl64k 65536 226 0 226 2 1 1 1 0 8 1 mcl16k 16384 2 0 2 1 0 1 1 0 8 1 mcl8k 8192 12 0 12 2 1 1 1 0 8 1 mcl4k 4096 3053 0 3002 15 7 8 15 0 8 0 mcl2k 2048 1052 0 1046 3 1 2 2 0 8 1 mtagpl 96 26 0 5 1 0 1 1 0 8 0 mbufpl 256 15393 0 15196 38 16 22 30 0 8 8 bufpl 280 4173 0 117 290 0 290 290 0 8 0 anonpl 24 105017 0 101796 58 12 46 46 0 187 10 amapchunkpl 152 27226 0 26524 40 5 35 35 0 158 2 amappl16 200 1247 0 1214 15 2 13 14 0 8 8 amappl15 192 3 0 3 1 1 0 1 0 8 0 amappl14 184 104 0 94 1 0 1 1 0 8 0 amappl13 176 3 0 3 1 1 0 1 0 8 0 amappl12 168 1484 0 1454 3 1 2 3 0 8 0 amappl11 160 45 0 35 1 0 1 1 0 8 0 amappl10 152 1 0 1 1 0 1 1 0 8 1 amappl9 144 254 0 254 1 1 0 1 0 8 0 amappl8 136 14 0 13 1 0 1 1 0 8 0 amappl7 128 97 0 87 1 0 1 1 0 8 0 amappl6 120 178 0 174 1 0 1 1 0 8 0 amappl5 112 113 0 106 1 0 1 1 0 8 0 amappl4 104 287 0 270 1 0 1 1 0 8 0 amappl3 96 4262 0 4146 4 0 4 4 0 8 1 amappl2 88 623 0 567 2 0 2 2 0 8 0 amappl1 80 9911 0 9361 13 1 12 13 0 8 0 amappl 88 6238 0 6066 5 0 5 5 0 92 1 dma4096 4096 1 0 1 1 1 0 1 0 8 0 dma2048 2048 1 0 1 1 0 1 1 0 8 1 dma1024 1024 1 0 0 1 0 1 1 0 8 0 dma256 256 7 0 7 2 1 1 1 0 8 1 dma128 128 253 0 253 1 1 0 1 0 8 0 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 24 0 4 1 0 1 1 0 8 0 uaddrrnd 24 857 0 827 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 857 0 827 1 0 1 1 0 8 0 vmmpekpl 168 8228 0 8187 3 0 3 3 0 8 0 vmmpepl 168 57429 0 55515 95 1 94 94 0 357 7 vmsppl 360 856 0 827 4 1 3 4 0 8 0 rwobjpl 32 19138 0 15427 31 0 31 31 0 8 0 pdppl 4096 1721 0 1654 103 34 69 83 0 8 2 pvpl 32 341502 0 332880 137 14 123 123 0 265 23 pmappl 216 856 0 827 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 316 0 69 8 0 8 8 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(ffffffff83434486) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833e3589,ffffffff83330725,3b7,ffffffff833e8da0) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80002a8b1b10,ffffffff8333358c) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80002a8b1b08) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002a7c2538) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c9793d0) at spec_close+0x412 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c1ff7f0,1,fffffd8007bfb618,ffff80002a7c2538) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156 vn_closefile(fffffd8069c97b50,ffff80002a7c2538) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8069c97b50,ffff80002a7c2538) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8069c97b50,ffff80002a7c2538) at fdrop+0x126 sys/kern/kern_descrip.c:1267 closef(fffffd8069c97b50,ffff80002a7c2538) at closef+0x18d sys/kern/kern_descrip.c:1251 fdfree(ffff80002a7c2538) at fdfree+0x115 sys/kern/kern_descrip.c:1182 exit1(ffff80002a7c2538,0,0,1) at exit1+0x59c sys/kern/kern_exit.c:215 sys_exit(ffff80002a7c2538,ffff80003c979740,ffff80003c979690) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c979740) at syscall+0x97e mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c979740) at syscall+0x97e sys/arch/amd64/amd64/trap.c:742 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72be53a7a0b0, 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(ffffffff83434486) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff833e3589,ffffffff83330725,3b7,ffffffff833e8da0) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80002a8b1b10,ffffffff8333358c) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80002a8b1b08) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002a7c2538) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c9793d0) at spec_close+0x412 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c1ff7f0,1,fffffd8007bfb618,ffff80002a7c2538) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156 vn_closefile(fffffd8069c97b50,ffff80002a7c2538) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8069c97b50,ffff80002a7c2538) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8069c97b50,ffff80002a7c2538) at fdrop+0x126 sys/kern/kern_descrip.c:1267 closef(fffffd8069c97b50,ffff80002a7c2538) at closef+0x18d sys/kern/kern_descrip.c:1251 fdfree(ffff80002a7c2538) at fdfree+0x115 sys/kern/kern_descrip.c:1182 exit1(ffff80002a7c2538,0,0,1) at exit1+0x59c sys/kern/kern_exit.c:215 sys_exit(ffff80002a7c2538,ffff80003c979740,ffff80003c979690) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c979740) at syscall+0x97e mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c979740) at syscall+0x97e sys/arch/amd64/amd64/trap.c:742 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72be53a7a0b0, count: -16