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 * 76910 69824 0 0 0x4000000 0 syz-executor 42900 23026 0 0 0 1 syz-executor db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83436e45) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e7132,ffffffff833edeb5,3b0,ffffffff833edefd) at __assert+0x29 refcnt_finalize(ffff80003b0cee08,ffffffff83331d8b) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(ffff80002a4a9000,ffff80003b0cee00) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80003b0c8a68) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c5569c0) at spec_close+0x412 VOP_CLOSE(fffffd8061b25e70,1,fffffd807f7d24e0,ffff80003b0c8a68) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8061aab0b8,ffff80003b0c8a68) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8061aab0b8,ffff80003b0c8a68) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd8061aab0b8,ffff80003b0c8a68) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd8061aab0b8,ffff80003b0c8a68) at closef+0x192 sys/kern/kern_descrip.c:1249 syscall(ffff80003c556c20) at syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c556c20) at syscall+0xbc6 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x29fa79325b0, count: 2 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(ffffffff83436e45) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e7132,ffffffff833edeb5,3b0,ffffffff833edefd) at __assert+0x29 refcnt_finalize(ffff80003b0cee08,ffffffff83331d8b) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(ffff80002a4a9000,ffff80003b0cee00) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80003b0c8a68) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c5569c0) at spec_close+0x412 VOP_CLOSE(fffffd8061b25e70,1,fffffd807f7d24e0,ffff80003b0c8a68) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8061aab0b8,ffff80003b0c8a68) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8061aab0b8,ffff80003b0c8a68) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd8061aab0b8,ffff80003b0c8a68) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd8061aab0b8,ffff80003b0c8a68) at closef+0x192 sys/kern/kern_descrip.c:1249 syscall(ffff80003c556c20) at syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c556c20) at syscall+0xbc6 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x29fa79325b0, count: -13 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff80003c556790 rbx 0xffffffff837f4dc7 cpu_info_full_primary+0x2dc7 rdx 0xffff80000002a740 rcx 0xffff80003b0c8a68 rax 0xffffffff837f3ff0 cpu_info_full_primary+0x1ff0 r8 0 r9 0x8080808080808080 r10 0x26774f12ea3c511b r11 0xf0518d0b753df60a r12 0xffffffff837f4bc8 cpu_info_full_primary+0x2bc8 r13 0 r14 0 r15 0x1 rip 0xffffffff8183fd15 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c556780 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor) tid=76910 pid=69824 tcnt=2 stat=onproc flags process=0 proc=4000000 runpri=32, usrpri=50, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0 forw=0xffffffffffffffff, list=0xffff80003b0c8cf8,0xffff80003b0c87e8 process=0xffff8000ffff5bb0 user=0xffff80003c551000, vmspace=0xfffffd806b216028 estcpu=36, cpticks=2, pctcpu=0.0, user=0, sys=2, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 97011 523439 25630 0 2 0 syz-executor 97011 18952 25630 0 3 0x4000080 fsleep syz-executor 69824 122356 79981 0 2 0 syz-executor *69824 76910 79981 0 7 0x4000000 syz-executor 44773 360920 49263 0 2 0 syz-executor 44773 6514 49263 0 3 0x4000000 smrbar syz-executor 23026 42900 74841 0 7 0 syz-executor 23026 227639 74841 0 3 0x4000080 fsleep syz-executor 28242 271032 70357 0 2 0 syz-executor 28242 238618 70357 0 3 0x4000080 fsleep syz-executor 59619 283279 66874 0 2 0 syz-executor 59619 10139 66874 0 3 0x4000080 lockf syz-executor 59619 403542 66874 0 3 0x4000080 fsleep syz-executor 59619 244956 66874 0 3 0x4000080 fsleep syz-executor 67488 328867 4296 0 3 0x82 sbwait sshd-session 57719 403069 0 0 3 0x14200 acct acct 49043 18007 0 0 3 0x14200 bored sosplice 49263 376863 16295 0 3 0x82 nanoslp syz-executor 14273 364444 16295 0 2 0x482 syz-executor 64523 195698 16295 0 3 0x82 wait syz-executor 74841 270031 16295 0 3 0x82 nanoslp syz-executor 70357 18787 16295 0 3 0x82 nanoslp syz-executor 25630 367905 16295 0 3 0x82 nanoslp syz-executor 66874 355400 16295 0 2 0x482 syz-executor 79981 476213 16295 0 2 0x482 syz-executor 16295 238924 36320 0 3 0x82 kqread syz-executor 36320 75600 48895 0 3 0x10008a sigsusp ksh 48895 129858 7765 0 3 0x98 kqread sshd-session 7765 342317 4296 0 3 0x92 kqread sshd-session 90923 399545 1 0 3 0x100083 ttyin getty 4296 136861 1 0 3 0x88 kqread sshd 15935 336735 72888 74 3 0x1100092 bpf pflogd 72888 250504 1 0 3 0x80 sbwait pflogd 91635 52440 10490 73 3 0x1100090 kqread syslogd 10490 368281 1 0 3 0x100082 sbwait syslogd 27134 41359 1 0 3 0x100080 kqread resolvd 28478 402411 41620 77 3 0x100092 kqread dhcpleased 8978 20689 41620 77 3 0x100092 kqread dhcpleased 41620 65715 1 0 3 0x80 kqread dhcpleased 31537 376938 0 0 2 0x40014200 smr 68115 386921 0 0 2 0x14200 zerothread 88366 18359 0 0 3 0x14200 aiodoned aiodoned 45112 161584 0 0 3 0x14200 syncer update 48031 420993 0 0 3 0x14200 cleaner cleaner 17718 270713 0 0 3 0x14200 reaper reaper 31226 49126 0 0 3 0x14200 pgdaemon pagedaemon 72443 315734 0 0 3 0x14200 bored viomb 3593 498151 0 0 3 0x40014200 acpi0 acpi0 21001 262518 0 0 3 0x40014200 idle1 95450 484940 0 0 3 0x14200 bored softnet3 97049 5174 0 0 3 0x14200 bored softnet2 975 60818 0 0 3 0x14200 bored softnet1 262 233474 0 0 3 0x14200 bored softnet0 23252 157803 0 0 3 0x14200 bored systqmp 30389 228047 0 0 3 0x14200 bored systq 60085 90354 0 0 3 0x14200 tmoslp softclockmp 88915 137163 0 0 2 0x40014200 softclock 14257 353331 0 0 3 0x40014200 idle0 1 203229 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}> show all locks Process 69824 (syz-executor) thread 0xffff80003b0c8a68 (76910) exclusive kernel_lock &kernel_lock r = 0 (0xffffffff83923ad8) #0 witness_lock+0x5bb stacktrace_save sys/sys/stacktrace.h:37 [inline] #0 witness_lock+0x5bb sys/kern/subr_witness.c:1155 #1 vn_closefile+0x41 sys/kern/vfs_vnops.c:608 #2 fdrop+0x126 sys/kern/kern_descrip.c:1265 #3 closef+0x192 sys/kern/kern_descrip.c:1249 #4 syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] #4 syscall+0xbc6 sys/arch/amd64/amd64/trap.c:577 #5 Xsyscall+0x128 ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10213 11163K 11411K 166960K 12362 0 pcb 19 15K 16K 166960K 185 0 rtable 259 10K 10K 166960K 422 0 pf 40 18K 22K 166960K 115 0 ifaddr 45 8K 8K 166960K 71 0 ifgroup 60 2K 2K 166960K 122 0 sysctl 3 1K 1K 166960K 3 0 counters 68 36K 37K 166960K 120 0 ioctlops 0 0K 4K 166960K 1530 0 iov 0 0K 16K 166960K 98 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1395 88K 88K 166960K 1805 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 3 5K 9K 166960K 13 0 VM map 2 1K 1K 166960K 2 0 sem 11 0K 0K 166960K 14 0 dirhash 12 2K 2K 166960K 33 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 93K 166960K 639 0 sigio 0 0K 0K 166960K 9 0 proc 73 91K 128K 166960K 600 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 58 0 in_multi 100 7K 7K 166960K 115 0 ether_multi 1 0K 0K 166960K 9 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 85 387K 387K 166960K 85 0 exec 0 0K 1K 166960K 457 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 255 74K 87K 166960K 7451 0 UVM aobj 18 2K 2K 166960K 18 0 pinsyscall 45 90K 103K 166960K 1737 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 18 0 NDP 13 0K 2K 166960K 47 0 temp 60 8640K 8752K 166960K 31532 0 kqueue 15 24K 28K 166960K 112 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 120 100 0 97 2 1 1 2 0 8 0 rtentry 112 124 0 9 4 0 4 4 0 8 0 unpcb 144 470 0 452 6 2 4 6 0 8 3 syncache 336 7 0 7 1 0 1 1 0 8 1 tcpqe 32 1 0 1 1 1 0 1 0 8 0 tcpcb 808 182 0 174 4 2 2 4 0 8 1 arp 120 18 0 0 1 0 1 1 0 8 0 inpcb 376 613 0 598 8 4 4 8 0 8 2 nd6 136 25 0 0 1 0 1 1 0 8 0 pkpcb 40 4 0 4 1 0 1 1 0 8 1 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1168 18 0 17 1 0 1 1 0 8 0 pppxif 1472 5 0 4 1 0 1 1 0 8 0 pfstscr 40 1 0 1 1 1 0 1 0 8 0 pffrag 232 3 0 2 2 1 1 1 0 482 0 pffrnode 88 3 0 2 2 1 1 1 0 8 0 pffrent 40 5 0 4 2 1 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 5 0 1 1 0 1 1 0 8 0 pfstitem 24 56 0 3 1 0 1 1 0 8 0 pfstkey 128 59 0 6 2 0 2 2 0 8 0 pfstate 376 58 0 5 6 0 6 6 0 8 0 pfrule 1344 26 0 19 2 1 1 2 0 8 0 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 491 0 24 30 0 30 30 0 8 0 art_table 32 493 0 24 4 0 4 4 0 8 0 art_node 16 119 0 15 1 0 1 1 0 8 0 sysvmsgpl 40 8 0 6 1 0 1 1 0 8 0 semupl 112 1 0 1 1 0 1 1 0 8 1 semapl 112 12 0 3 1 0 1 1 0 8 0 shmpl 112 15 0 0 1 0 1 1 0 8 0 dirhash 1024 31 0 14 3 0 3 3 0 8 0 dino2pl 256 2489 0 985 95 0 95 95 0 8 0 ffsino 280 2489 0 985 109 0 109 109 0 8 0 nchpl 144 3371 0 1678 63 0 63 63 0 8 0 rtmask 32 3 0 3 2 1 1 1 0 8 1 uvmvnodes 80 2865 0 0 59 0 59 59 0 8 0 vnodes 216 2865 0 0 160 0 160 160 0 8 0 namei 1024 11212 0 11212 2 1 1 2 0 8 1 percpumem 16 74 0 26 1 0 1 1 0 8 0 kstatmem 264 62 0 36 2 0 2 2 0 8 0 scsiplug 72 2 0 2 1 1 0 1 0 8 0 scxspl 216 12676 0 12676 10 2 8 8 1 8 8 plimitpl 152 96 0 77 1 0 1 1 0 8 0 sigapl 424 943 0 890 8 1 7 7 0 8 1 futexpl 64 8070 0 8065 1 0 1 1 0 8 0 knotepl 120 314 0 0 10 0 10 10 0 8 0 kqueuepl 216 240 0 227 3 0 3 3 0 8 2 pipepl 328 211 0 183 8 4 4 8 0 8 1 fdescpl 504 923 0 890 5 0 5 5 0 8 0 filepl 152 4936 0 4697 15 2 13 15 0 8 2 lockfpl 104 148 0 142 1 0 1 1 0 8 0 lockfspl 48 61 0 57 1 0 1 1 0 8 0 sessionpl 144 26 0 16 1 0 1 1 0 8 0 pgrppl 48 40 0 22 1 0 1 1 0 8 0 ucredpl 104 590 0 576 1 0 1 1 0 8 0 zombiepl 144 892 0 890 1 0 1 1 0 8 0 processpl 1176 943 0 890 5 0 5 5 0 8 0 procpl 656 1780 0 1719 7 1 6 7 0 8 0 sosppl 168 1 0 1 1 0 1 1 0 8 1 sockpl 688 1230 0 1194 18 8 10 18 0 8 6 mcl64k 65536 3 0 0 1 0 1 1 0 8 0 mcl12k 12288 1 0 0 1 0 1 1 0 8 0 mcl8k 8192 6 0 0 1 0 1 1 0 8 0 mcl4k 4096 113 0 0 15 0 15 15 0 8 0 mcl2k 2048 33 0 0 4 0 4 4 0 8 0 mtagpl 96 60 0 0 2 0 2 2 0 8 0 mbufpl 256 279 0 0 18 0 18 18 0 8 0 bufpl 280 4285 0 132 297 0 297 297 0 8 0 anonpl 24 144587 0 138924 62 3 59 59 0 184 0 amapchunkpl 152 23806 0 23170 30 2 28 28 0 158 2 amappl16 200 2762 0 2691 19 2 17 17 0 8 6 amappl15 192 9 0 9 1 1 0 1 0 8 0 amappl14 184 170 0 157 1 0 1 1 0 8 0 amappl13 176 3 0 3 1 1 0 1 0 8 0 amappl12 168 1565 0 1532 4 2 2 3 0 8 0 amappl11 160 53 0 38 1 0 1 1 0 8 0 amappl10 152 2 0 2 1 1 0 1 0 8 0 amappl9 144 251 0 251 1 1 0 1 0 8 0 amappl8 136 24 0 21 1 0 1 1 0 8 0 amappl7 128 109 0 96 1 0 1 1 0 8 0 amappl6 120 183 0 179 1 0 1 1 0 8 0 amappl5 112 159 0 149 1 0 1 1 0 8 0 amappl4 104 327 0 307 1 0 1 1 0 8 0 amappl3 96 4628 0 4503 4 0 4 4 0 8 0 amappl2 88 700 0 632 2 0 2 2 0 8 0 amappl1 80 10228 0 9572 17 1 16 16 0 8 0 amappl 88 7033 0 6839 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 8 0 8 3 2 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 19 0 18 1 0 1 1 0 8 0 aobjpl 72 17 0 0 1 0 1 1 0 8 0 uaddrrnd 24 923 0 890 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 923 0 890 1 0 1 1 0 8 0 vmmpekpl 168 9439 0 9394 3 0 3 3 0 8 0 vmmpepl 168 62747 0 60636 105 1 104 104 0 357 3 vmsppl 456 922 0 890 6 1 5 5 0 8 0 rwobjpl 64 22164 0 18188 68 0 68 68 0 8 0 pdppl 4096 1854 0 1780 106 30 76 86 0 8 2 pvpl 32 18640 0 0 152 1 151 152 0 265 0 pmappl 248 922 0 890 3 0 3 3 0 8 0 extentpl 40 55 0 38 1 0 1 1 0 8 0 phpool 112 293 0 36 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(ffffffff83436e45) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff833e7132,ffffffff833edeb5,3b0,ffffffff833edefd) at __assert+0x29 refcnt_finalize(ffff80003b0cee08,ffffffff83331d8b) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945 pppx_if_destroy(ffff80002a4a9000,ffff80003b0cee00) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806 pppxclose(205b9a,1,2000,ffff80003b0c8a68) at pppxclose+0xa0 sys/net/if_pppx.c:553 spec_close(ffff80003c5569c0) at spec_close+0x412 VOP_CLOSE(fffffd8061b25e70,1,fffffd807f7d24e0,ffff80003b0c8a68) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8061aab0b8,ffff80003b0c8a68) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8061aab0b8,ffff80003b0c8a68) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd8061aab0b8,ffff80003b0c8a68) at fdrop+0x126 sys/kern/kern_descrip.c:1265 closef(fffffd8061aab0b8,ffff80003b0c8a68) at closef+0x192 sys/kern/kern_descrip.c:1249 syscall(ffff80003c556c20) at syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c556c20) at syscall+0xbc6 sys/arch/amd64/amd64/trap.c:577 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x29fa79325b0, count: -13 ddb{0}> machine ddbcpu 1