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(ffffffff83488559) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c2d6c,ffffffff8351f0b6,3bb,ffffffff834f81d9) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9071d0,ffffffff8347d232) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80003c9071c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,1,2000,ffff80002a75b770) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003aceba90) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806d2c3b00,1,fffffd8007ffd888,ffff80002a75b770) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806c8eb880,ffff80002a75b770) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffd806c8eb880,ffff80002a75b770) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffd806c8eb880,ffff80002a75b770) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffd806c8eb880,ffff80002a75b770) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80002a75b770) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80002a75b770,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a75b770,ffff80003acebdf0,ffff80003acebd40) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff80003acebde0, 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(ffffffff83488559) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c2d6c,ffffffff8351f0b6,3bb,ffffffff834f81d9) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9071d0,ffffffff8347d232) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80003c9071c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,1,2000,ffff80002a75b770) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003aceba90) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806d2c3b00,1,fffffd8007ffd888,ffff80002a75b770) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806c8eb880,ffff80002a75b770) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffd806c8eb880,ffff80002a75b770) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffd806c8eb880,ffff80002a75b770) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffd806c8eb880,ffff80002a75b770) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80002a75b770) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80002a75b770,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a75b770,ffff80003acebdf0,ffff80003acebd40) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003acebdf0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003acebdf0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x73ce85c38d10, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003aceb870 rbx 0 rdx 0 rcx 0 rax 0xffff80002a75b770 r8 0x101010101010101 r9 0x8080808080808080 r10 0x630dede85546208 r11 0xe0714e3ba74b79b7 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff82f1cff5 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003aceb860 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=349798 pid=44583 tcnt=0 stat=onproc flags process=1009 proc=2000 runpri=26, usrpri=50, slppri=26, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a75b770 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a790540,0xffff80002a77c030 process=0xffff8000ffff9f98 user=0xffff80003ace6000, vmspace=0xfffffd806cab72f0 estcpu=0, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 45214 83354 87769 0 2 0 syz-executor 45214 87742 87769 0 2 0x4000000 syz-executor 49068 17487 2291 0 2 0 syz-executor 49068 79350 2291 0 3 0x4000080 fsleep syz-executor 83975 137956 79090 0 2 0xc80 syz-executor 83975 28896 79090 0 3 0x4000000 smrbar syz-executor 83975 189148 79090 0 3 0x4000080 fsleep syz-executor 20690 160417 19293 0 2 0xc80 syz-executor 20690 474008 19293 0 3 0x4000080 dtread syz-executor 20690 506 19293 0 3 0x4000080 dtread syz-executor 48469 109567 51636 0 2 0 syz-executor 48469 453952 51636 0 3 0x4000080 kqread syz-executor 57080 293134 86499 0 2 0xc80 syz-executor 57080 512906 86499 0 3 0x4000080 lockf syz-executor 57080 260375 86499 0 3 0x4000080 fsleep syz-executor 37605 4606 96565 0 2 0xc80 syz-executor 37605 84782 96565 0 3 0x4000080 netcon syz-executor 37605 429979 96565 0 3 0x4000080 fsleep syz-executor 28470 266383 1 0 3 0x100083 ttyin getty 76209 430873 79280 0 3 0x82 wait syz-executor 86499 483329 79280 0 2 0xc82 syz-executor 87769 69884 79280 0 2 0xc82 syz-executor 96565 468391 79280 0 2 0xc82 syz-executor 51636 447814 79280 0 2 0xc82 syz-executor 79090 399945 79280 0 2 0xc82 syz-executor 19293 152098 79280 0 2 0xc82 syz-executor 2291 434127 79280 0 2 0xc82 syz-executor 79280 355478 1 0 2 0xc82 syz-executor 51138 390445 1 73 3 0x1100090 kqread syslogd 35061 85987 0 0 2 0x14200 smr 17952 155497 0 0 2 0x14200 zerothread 33492 500736 0 0 3 0x14200 aiodoned aiodoned 45490 17821 0 0 2 0x14e00 update 30563 23519 0 0 3 0x14200 cleaner cleaner 13565 194291 0 0 3 0x14200 reaper reaper 37731 90131 0 0 3 0x14200 pgdaemon pagedaemon 15224 50757 0 0 3 0x14200 bored viomb 31300 100957 0 0 3 0x40014200 acpi0 acpi0 75546 352931 0 0 2 0x14200 softnet0 71583 96493 0 0 3 0x14200 smrbar systqmp 10315 126500 0 0 3 0x14200 bored systq 98690 17322 0 0 2 0x40014200 softclock 82163 342836 0 0 3 0x40014200 idle0 1 174535 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 11067 12191K 12309K 166960K 12351 0 pcb 19 14K 16K 166960K 62 0 rtable 213 7K 8K 166960K 399 0 pf 33 13K 17K 166960K 55 0 ifaddr 37 6K 7K 166960K 50 0 ifgroup 49 2K 2K 166960K 61 0 sysctl 3 1K 9K 166960K 8 0 counters 34 17K 18K 166960K 38 0 ioctlops 0 0K 4K 166960K 67 0 iov 0 0K 8K 166960K 8 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1389 87K 88K 166960K 1648 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 5K 166960K 5 0 VM map 2 1K 1K 166960K 2 0 sem 11 0K 0K 166960K 17 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 97K 166960K 311 0 sigio 0 0K 0K 166960K 3 0 proc 19 25K 116K 166960K 537 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 16 0 in_multi 77 5K 7K 166960K 105 0 ether_multi 1 0K 0K 166960K 3 0 mrt 1 0K 0K 166960K 7 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 253 1129K 1129K 166960K 253 0 exec 0 0K 1K 166960K 381 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 158 91K 159K 166960K 4474 0 UVM aobj 8 2K 2K 166960K 10 0 pinsyscall 22 44K 95K 166960K 1429 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 8 0 NDP 11 0K 2K 166960K 31 0 temp 45 9104K 9166K 166960K 10586 0 kqueue 6 9K 26K 166960K 54 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 49 0 49 1 0 1 1 0 8 1 rtentry 136 119 0 27 4 0 4 4 0 8 0 unpcb 144 107 0 101 1 0 1 1 0 8 0 syncache 336 4 0 4 1 0 1 1 0 8 1 tcpcb 736 32 0 30 1 0 1 1 0 8 0 arp 96 20 0 6 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 328 324 0 319 9 0 9 9 0 8 8 ip6q 72 1 0 0 1 0 1 1 0 8 0 ip6af 40 1 0 0 1 0 1 1 0 8 0 nd6 112 26 0 6 1 0 1 1 0 8 0 pkpcb 40 3 0 3 1 0 1 1 0 8 1 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1072 4 0 2 1 0 1 1 0 8 0 pppxif 1416 1 0 0 1 0 1 1 0 8 0 pfstscr 40 2 0 0 1 0 1 1 0 8 0 pfrktable 1344 3 0 1 1 0 1 1 0 8 0 pfanchor 1288 2 0 0 1 0 1 1 0 8 0 pfqueue 320 1 0 1 1 0 1 1 0 8 1 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 1360 2 0 1 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 472 0 48 30 0 30 30 0 8 1 art_table 40 473 0 48 5 0 5 5 0 8 0 art_node 32 119 0 26 1 0 1 1 0 8 0 sysvmsgpl 40 40 0 0 1 0 1 1 0 8 0 semupl 112 1 0 1 1 0 1 1 0 8 1 semapl 72 14 0 5 1 0 1 1 0 8 0 shmpl 112 7 0 2 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1930 0 472 92 0 92 92 0 8 0 ffsino 256 1930 0 472 92 0 92 92 0 8 0 nchpl 144 2361 0 659 64 0 64 64 0 8 0 vnodes 216 2184 0 0 122 0 122 122 0 8 0 namei 1024 7564 0 7564 2 0 2 2 0 8 2 pfiaddrpl 120 1 0 0 1 0 1 1 0 8 0 kstatmem 264 31 0 8 2 0 2 2 0 8 0 scsiplug 72 1 0 1 1 0 1 1 0 8 1 scxspl 216 7898 0 7898 8 0 8 8 1 8 8 plimitpl 152 110 0 99 1 0 1 1 0 8 0 sigapl 424 611 0 577 6 0 6 6 0 8 1 knotepl 120 10655 0 10630 16 6 10 16 0 8 8 kqueuepl 184 63 0 57 1 0 1 1 0 8 0 pipepl 304 128 0 101 3 0 3 3 0 8 0 fdescpl 448 598 0 577 5 0 5 5 0 8 1 filepl 120 2924 0 2735 10 0 10 10 0 8 2 lockfpl 104 196 0 194 2 0 2 2 0 8 1 lockfspl 48 91 0 90 1 0 1 1 0 8 0 sessionpl 144 34 0 29 1 0 1 1 0 8 0 pgrppl 48 42 0 29 1 0 1 1 0 8 0 ucredpl 104 532 0 527 1 0 1 1 0 8 0 zombiepl 144 578 0 577 1 0 1 1 0 8 0 processpl 1152 611 0 577 4 0 4 4 0 8 0 procpl 664 879 0 834 5 0 5 5 0 8 0 sockpl 552 490 0 479 8 0 8 8 0 8 7 mcl64k 65536 9 0 9 1 0 1 1 0 8 1 mcl8k 8192 10 0 10 1 0 1 1 0 8 1 mcl4k 4096 2726 0 2668 14 0 14 14 0 8 5 mcl2k 2048 272 0 267 2 0 2 2 0 8 1 mtagpl 96 5 0 4 1 0 1 1 0 8 0 mbufpl 256 6100 0 5919 13 0 13 13 0 8 0 bufpl 280 2521 0 103 173 0 173 173 0 8 0 anonpl 24 103392 0 101365 32 0 32 32 0 186 13 amapchunkpl 152 19353 0 18940 34 0 34 34 0 158 16 amappl16 200 1624 0 1605 5 0 5 5 0 8 3 amappl15 192 21 0 21 1 0 1 1 0 8 1 amappl14 184 412 0 412 1 0 1 1 0 8 1 amappl13 176 120 0 118 1 0 1 1 0 8 0 amappl12 168 844 0 824 2 0 2 2 0 8 0 amappl11 160 13 0 13 1 0 1 1 0 8 1 amappl10 152 58 0 56 1 0 1 1 0 8 0 amappl9 144 268 0 268 1 0 1 1 0 8 1 amappl8 136 92 0 92 1 0 1 1 0 8 1 amappl7 128 146 0 141 1 0 1 1 0 8 0 amappl6 120 149 0 148 1 0 1 1 0 8 0 amappl5 112 107 0 104 1 0 1 1 0 8 0 amappl4 104 266 0 258 1 0 1 1 0 8 0 amappl3 96 2527 0 2435 4 0 4 4 0 8 0 amappl2 88 532 0 516 2 0 2 2 0 8 0 amappl1 80 10988 0 10825 13 0 13 13 0 8 2 amappl 88 3741 0 3606 5 0 5 5 0 92 1 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 128 253 0 253 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 9 0 2 1 0 1 1 0 8 0 uaddrrnd 24 598 0 577 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 598 0 577 1 0 1 1 0 8 0 vmmpekpl 168 6641 0 6610 2 0 2 2 0 8 0 vmmpepl 168 46203 0 45197 81 0 81 81 0 357 35 vmsppl 368 597 0 577 4 0 4 4 0 8 1 rwobjpl 40 15833 0 15334 11 0 11 11 0 8 0 pdppl 4096 1202 0 1154 96 48 48 82 0 8 0 pvpl 32 270728 0 265316 92 0 92 92 0 265 31 pmappl 216 597 0 577 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 362 0 48 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(ffffffff83488559) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c2d6c,ffffffff8351f0b6,3bb,ffffffff834f81d9) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9071d0,ffffffff8347d232) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80003c9071c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,1,2000,ffff80002a75b770) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003aceba90) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806d2c3b00,1,fffffd8007ffd888,ffff80002a75b770) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806c8eb880,ffff80002a75b770) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffd806c8eb880,ffff80002a75b770) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffd806c8eb880,ffff80002a75b770) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffd806c8eb880,ffff80002a75b770) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80002a75b770) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80002a75b770,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a75b770,ffff80003acebdf0,ffff80003acebd40) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003acebdf0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003acebdf0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x73ce85c38d10, 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(ffffffff83488559) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c2d6c,ffffffff8351f0b6,3bb,ffffffff834f81d9) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9071d0,ffffffff8347d232) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80003c9071c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,1,2000,ffff80002a75b770) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003aceba90) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806d2c3b00,1,fffffd8007ffd888,ffff80002a75b770) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806c8eb880,ffff80002a75b770) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffd806c8eb880,ffff80002a75b770) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffd806c8eb880,ffff80002a75b770) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffd806c8eb880,ffff80002a75b770) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80002a75b770) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80002a75b770,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a75b770,ffff80003acebdf0,ffff80003acebd40) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003acebdf0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003acebdf0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x73ce85c38d10, count: -16 ddb>