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(ffffffff83339972) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a503,ffffffff833dbf3e,3b7,ffffffff833b5f37) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9b70b0,ffffffff833334be) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b92,ffff80003c9b70a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80003a568558) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800030d36f70) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd8060f95470,41,fffffd8007bfb750,ffff80003a568558) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806180cae0,ffff80003a568558) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806180cae0,ffff80003a568558) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806180cae0,ffff80003a568558) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806180cae0,ffff80003a568558) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003a568558) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003a568558,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003a568558,ffff800030d372d0,ffff800030d37220) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff800030d372c0, 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(ffffffff83339972) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a503,ffffffff833dbf3e,3b7,ffffffff833b5f37) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9b70b0,ffffffff833334be) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b92,ffff80003c9b70a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80003a568558) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800030d36f70) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd8060f95470,41,fffffd8007bfb750,ffff80003a568558) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806180cae0,ffff80003a568558) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806180cae0,ffff80003a568558) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806180cae0,ffff80003a568558) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806180cae0,ffff80003a568558) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003a568558) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003a568558,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003a568558,ffff800030d372d0,ffff800030d37220) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800030d372d0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800030d372d0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x76e0276bcc90, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff800030d36d50 rbx 0 rdx 0 rcx 0 rax 0xffff80003a568558 r8 0x101010101010101 r9 0x8080808080808080 r10 0xb73ac3188e998670 r11 0x3124744ca7662521 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff816ffe35 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff800030d36d40 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=420753 pid=99748 tcnt=0 stat=onproc flags process=1018 proc=2000 runpri=32, usrpri=50, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80003a568558 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80003a5682c0,0xffff80003a568800 process=0xffff80003c986940 user=0xffff800030d32000, vmspace=0xfffffd806ba6ba20 estcpu=36, cpticks=0, pctcpu=0.0, user=0, sys=0, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 59498 127680 42241 0 2 0 syz-executor 59498 492804 42241 0 3 0x4000000 smrbar syz-executor 58202 34353 45157 0 2 0xc80 syz-executor 58202 229828 45157 0 3 0x4000080 fsleep syz-executor 58202 180056 45157 0 3 0x4000080 fsleep syz-executor 58202 82315 45157 0 3 0x4000080 kqsel syz-executor 13119 359675 31566 0 3 0x80 nanoslp syz-executor 13119 81672 31566 0 3 0x4000080 fsleep syz-executor 13119 416994 31566 0 3 0x4000080 wsevent_read syz-executor 13119 67908 31566 0 3 0x4000080 wsevent_read syz-executor 13119 58258 31566 0 3 0x4000080 fsleep syz-executor 68573 415933 62179 0 3 0x3000 suspend syz-executor 68573 411714 62179 0 2 0x4081000 syz-executor 5893 70610 0 0 3 0x14200 acct acct 4252 132700 0 0 3 0x14200 bored sosplice 59740 62807 41828 0 3 0x82 nanoslp syz-executor 31566 2709 41828 0 2 0x2 syz-executor 38390 232241 41828 0 3 0x82 nanoslp syz-executor 41573 389247 41828 0 2 0xc82 syz-executor 42241 402924 41828 0 2 0xc82 syz-executor 81852 124000 41828 0 3 0x82 nanoslp syz-executor 45157 197248 41828 0 3 0x82 nanoslp syz-executor 62179 274022 41828 0 3 0x82 nanoslp syz-executor 41828 240636 39996 0 3 0x82 kqread syz-executor 39996 250319 61019 0 3 0x10008a sigsusp ksh 61019 231714 93911 0 3 0x98 kqread sshd-session 93911 95643 958 0 3 0x92 kqread sshd-session 54359 452615 1 0 3 0x100083 ttyin getty 958 486919 1 0 3 0x88 kqread sshd 41978 19542 16239 73 3 0x1100090 kqread syslogd 16239 469733 1 0 3 0x100082 sbwait syslogd 21187 222570 1 0 3 0x100080 kqread resolvd 42618 138065 15461 77 3 0x100092 kqread dhcpleased 64401 74272 15461 77 3 0x100092 kqread dhcpleased 15461 35414 1 0 3 0x80 kqread dhcpleased 55072 236055 0 0 3 0x14200 bored smr 92240 87167 0 0 2 0x14200 zerothread 47064 13942 0 0 3 0x14200 aiodoned aiodoned 4297 179124 0 0 3 0x14200 syncer update 76768 104376 0 0 3 0x14200 cleaner cleaner 76629 463904 0 0 3 0x14200 reaper reaper 42327 101180 0 0 3 0x14200 pgdaemon pagedaemon 24884 453628 0 0 3 0x14200 bored viomb 65058 499540 0 0 3 0x40014200 acpi0 acpi0 72943 105990 0 0 3 0x14200 bored softnet7 67573 43570 0 0 3 0x14200 bored softnet6 41134 324865 0 0 3 0x14200 bored softnet5 3142 27313 0 0 3 0x14200 bored softnet4 60384 12929 0 0 3 0x14200 bored softnet3 23462 221870 0 0 3 0x14200 bored softnet2 16646 407576 0 0 3 0x14200 bored softnet1 23944 506517 0 0 3 0x14200 bored softnet0 91167 23719 0 0 3 0x14200 bored systqmp 6280 115965 0 0 3 0x14200 bored systq 31723 182221 0 0 2 0x40014200 softclock 34548 241397 0 0 3 0x40014200 idle0 1 188249 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 10190 11053K 11252K 166960K 11638 0 pcb 18 16K 18K 166960K 87 0 rtable 176 7K 7K 166960K 322 0 pf 36 14K 15K 166960K 63 0 ifaddr 39 6K 7K 166960K 61 0 ifgroup 57 2K 2K 166960K 85 0 sysctl 1 1K 9K 166960K 6 0 counters 36 18K 18K 166960K 56 0 ioctlops 0 0K 4K 166960K 78 0 iov 0 0K 12K 166960K 16 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1460 92K 92K 166960K 1774 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 5K 166960K 9 0 VM map 2 1K 1K 166960K 2 0 sem 11 1K 1K 166960K 51 0 dirhash 12 2K 2K 166960K 24 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 240K 166960K 391 0 sigio 1 0K 0K 166960K 6 0 proc 60 59K 124K 166960K 501 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 1 0K 0K 166960K 33 0 in_multi 80 5K 7K 166960K 109 0 ether_multi 2 0K 0K 166960K 2 0 mrt 0 0K 0K 166960K 1 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 438 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 233 151K 167K 166960K 4945 0 UVM aobj 11 2K 2K 166960K 12 0 pinsyscall 39 78K 96K 166960K 1420 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 25 0 NDP 13 0K 2K 166960K 39 0 temp 45 8635K 8699K 166960K 6827 0 kqueue 14 22K 27K 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 56 0 53 1 0 1 1 0 8 0 rtentry 136 105 0 35 4 0 4 4 0 8 0 unpcb 144 195 0 179 2 0 2 2 0 8 1 syncache 336 5 0 5 2 1 1 1 0 8 1 tcpqe 32 1 0 1 1 1 0 1 0 8 0 tcpcb 736 148 0 142 7 0 7 7 0 8 6 arp 88 10 0 2 1 0 1 1 0 8 0 ipq 40 1 0 0 1 0 1 1 0 8 0 ipqe 40 4 0 2 1 0 1 1 0 8 0 inpcb 328 455 0 445 10 1 9 10 0 8 8 ip6q 72 1 0 1 1 1 0 1 0 8 0 ip6af 40 2 0 2 1 1 0 1 0 8 0 nd6 104 19 0 4 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 20 0 17 2 1 1 1 0 8 0 pppxif 1384 2 0 1 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 4 0 4 2 1 1 1 0 8 1 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 516 0 149 30 0 30 30 0 8 6 art_table 40 517 0 149 5 0 5 5 0 8 0 art_node 32 103 0 41 1 0 1 1 0 8 0 sysvmsgpl 40 3 0 3 1 0 1 1 0 8 1 semupl 112 3 0 3 2 1 1 1 0 8 1 semapl 112 48 0 39 1 0 1 1 0 8 0 shmpl 112 9 0 1 1 0 1 1 0 8 0 dirhash 1024 25 0 8 3 0 3 3 0 8 0 dino2pl 256 2132 0 637 95 0 95 95 0 8 0 ffsino 256 2132 0 637 95 0 95 95 0 8 0 nchpl 144 2642 0 959 63 0 63 63 0 8 0 rtmask 32 4 0 4 2 1 1 1 0 8 1 uvmvnodes 80 2475 0 0 51 0 51 51 0 8 0 vnodes 216 2475 0 0 138 0 138 138 0 8 0 namei 1024 9513 0 9513 2 1 1 2 0 8 1 kstatmem 264 46 0 20 2 0 2 2 0 8 0 scsiplug 72 1 0 1 1 0 1 1 0 8 1 scxspl 216 9429 0 9429 15 7 8 8 1 8 8 plimitpl 152 195 0 177 1 0 1 1 0 8 0 sigapl 424 666 0 614 7 1 6 7 0 8 0 knotepl 120 13718 0 13669 15 6 9 9 0 8 7 kqueuepl 184 121 0 105 1 0 1 1 0 8 0 pipepl 304 182 0 154 8 0 8 8 0 8 5 fdescpl 448 644 0 614 5 1 4 5 0 8 0 filepl 120 3902 0 3671 14 1 13 13 0 8 5 lockfpl 104 321 0 319 2 0 2 2 0 8 1 lockfspl 48 54 0 52 1 0 1 1 0 8 0 sessionpl 144 23 0 15 1 0 1 1 0 8 0 pgrppl 48 42 0 26 1 0 1 1 0 8 0 ucredpl 104 603 0 589 1 0 1 1 0 8 0 zombiepl 144 619 0 614 2 1 1 1 0 8 0 processpl 1168 666 0 614 5 1 4 5 0 8 0 procpl 664 1058 0 997 6 0 6 6 0 8 0 sockpl 552 713 0 684 14 3 11 13 0 8 8 mcl64k 65536 25 0 25 3 2 1 2 0 8 1 mcl16k 16384 5 0 5 1 1 0 1 0 8 0 mcl9k 9216 1 0 1 1 0 1 1 0 8 1 mcl8k 8192 71 0 71 2 1 1 1 0 8 1 mcl4k 4096 2808 0 2756 14 6 8 13 0 8 1 mcl2k 2048 566 0 561 3 0 3 3 0 8 2 mtagpl 96 6 0 6 2 1 1 1 0 8 1 mbufpl 256 6841 0 6689 14 0 14 14 0 8 3 bufpl 280 3507 0 114 243 0 243 243 0 8 0 anonpl 24 118325 0 113873 37 2 35 35 0 187 7 amapchunkpl 152 15630 0 15138 38 5 33 33 0 158 13 amappl16 200 2267 0 2157 13 3 10 10 0 8 3 amappl15 192 3 0 3 1 1 0 1 0 8 0 amappl14 184 111 0 101 1 0 1 1 0 8 0 amappl13 176 7 0 7 1 1 0 1 0 8 0 amappl12 168 1287 0 1257 3 1 2 3 0 8 0 amappl11 160 46 0 36 1 0 1 1 0 8 0 amappl10 152 5 0 5 1 1 0 1 0 8 0 amappl9 144 317 0 317 1 1 0 1 0 8 0 amappl8 136 22 0 21 1 0 1 1 0 8 0 amappl7 128 119 0 109 1 0 1 1 0 8 0 amappl6 120 170 0 167 1 0 1 1 0 8 0 amappl5 112 121 0 115 1 0 1 1 0 8 0 amappl4 104 276 0 259 1 0 1 1 0 8 0 amappl3 96 2809 0 2698 4 0 4 4 0 8 1 amappl2 88 629 0 574 2 0 2 2 0 8 0 amappl1 80 9331 0 8786 14 1 13 13 0 8 1 amappl 88 4236 0 4067 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 19 0 18 1 0 1 1 0 8 0 aobjpl 72 11 0 1 1 0 1 1 0 8 0 uaddrrnd 24 644 0 614 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 644 0 614 1 0 1 1 0 8 0 vmmpekpl 168 6871 0 6841 2 0 2 2 0 8 0 vmmpepl 168 47202 0 45222 94 4 90 90 0 357 3 vmsppl 368 643 0 614 4 1 3 4 0 8 0 rwobjpl 40 17587 0 14175 35 0 35 35 0 8 0 pdppl 4096 1294 0 1228 106 40 66 82 0 8 0 pvpl 32 296207 0 285788 95 1 94 94 0 265 9 pmappl 216 643 0 614 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 395 0 57 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(ffffffff83339972) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a503,ffffffff833dbf3e,3b7,ffffffff833b5f37) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9b70b0,ffffffff833334be) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b92,ffff80003c9b70a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80003a568558) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800030d36f70) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd8060f95470,41,fffffd8007bfb750,ffff80003a568558) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806180cae0,ffff80003a568558) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806180cae0,ffff80003a568558) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806180cae0,ffff80003a568558) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806180cae0,ffff80003a568558) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003a568558) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003a568558,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003a568558,ffff800030d372d0,ffff800030d37220) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800030d372d0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800030d372d0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x76e0276bcc90, 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(ffffffff83339972) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a503,ffffffff833dbf3e,3b7,ffffffff833b5f37) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9b70b0,ffffffff833334be) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b92,ffff80003c9b70a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80003a568558) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800030d36f70) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd8060f95470,41,fffffd8007bfb750,ffff80003a568558) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806180cae0,ffff80003a568558) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806180cae0,ffff80003a568558) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806180cae0,ffff80003a568558) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806180cae0,ffff80003a568558) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003a568558) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003a568558,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003a568558,ffff800030d372d0,ffff800030d37220) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800030d372d0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800030d372d0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x76e0276bcc90, count: -16