panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 953 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(ffffffff83337325) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff83379585,ffffffff833d39ae,3b9,ffffffff833ace54) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c95ab48,ffffffff8332da66) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c95ab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002a7abca0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800031506c20) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd807e2b7cb0,1,fffffd8007bfb680,ffff80002a7abca0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd805f4f31e8,ffff80002a7abca0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805f4f31e8,ffff80002a7abca0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805f4f31e8,ffff80002a7abca0) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd805f4f31e8,ffff80002a7abca0) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7abca0) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7abca0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7abca0,ffff800031506f80,ffff800031506ed0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff800031506f70, 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 953 ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83337325) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff83379585,ffffffff833d39ae,3b9,ffffffff833ace54) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c95ab48,ffffffff8332da66) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c95ab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002a7abca0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800031506c20) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd807e2b7cb0,1,fffffd8007bfb680,ffff80002a7abca0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd805f4f31e8,ffff80002a7abca0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805f4f31e8,ffff80002a7abca0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805f4f31e8,ffff80002a7abca0) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd805f4f31e8,ffff80002a7abca0) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7abca0) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7abca0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7abca0,ffff800031506f80,ffff800031506ed0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800031506f80) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800031506f80) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72a15b136980, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff800031506a00 rbx 0 rdx 0 rcx 0 rax 0xffff80002a7abca0 r8 0x101010101010101 r9 0x8080808080808080 r10 0x37b1f895cfe368a4 r11 0x69e5d01495cb6f8 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff82562815 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff8000315069f0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=431999 pid=53291 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=50, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80002a7abca0 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a7ab4d8,0xffff80002a7aaa88 process=0xffff8000ffff9f98 user=0xffff800031502000, vmspace=0xfffffd806ba2be70 estcpu=36, cpticks=2, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 79622 201922 99930 0 2 0 syz-executor 79622 335661 99930 0 3 0x4000000 smrbar syz-executor 52969 110355 50377 0 2 0 syz-executor 44523 137625 61089 0 3 0x80 nanoslp syz-executor 44523 106768 61089 0 3 0x4000080 msgwait syz-executor 44523 99674 61089 0 3 0x4000080 fsleep syz-executor 44523 98103 61089 0 3 0x4000080 fsleep syz-executor 65659 226903 19438 0 2 0 syz-executor 65659 421418 19438 0 3 0x4000080 fsleep syz-executor 65659 340606 19438 0 3 0x4000080 fsleep syz-executor 65659 304520 19438 0 3 0x4000080 fsleep syz-executor 51439 220742 18929 0 2 0xc80 syz-executor 51439 97150 18929 0 3 0x4000080 kqread syz-executor 51439 190635 18929 0 3 0x4000080 fsleep syz-executor 51439 212320 18929 0 3 0x4000080 fsleep syz-executor 25594 341892 1 0 3 0x100083 ttyopn getty 52874 328614 11803 0 2 0xc82 syz-executor 41393 129716 0 0 3 0x14200 bored sosplice 64486 217297 11803 0 3 0x82 nanoslp syz-executor 9490 69805 11803 0 3 0x82 piperd syz-executor 99930 118929 11803 0 2 0xc82 syz-executor 18929 322010 11803 0 2 0xc82 syz-executor 19438 318739 11803 0 2 0xc82 syz-executor 50377 137187 11803 0 2 0xc82 syz-executor 61089 336065 11803 0 2 0xc82 syz-executor 11803 155758 71196 0 2 0x2 syz-executor 71196 206920 26647 0 3 0x10008a sigsusp ksh 26647 217640 44116 0 3 0x98 kqread sshd-session 44116 508004 75157 0 3 0x92 kqread sshd-session 75157 360069 1 0 3 0x88 kqread sshd 80584 340081 38224 73 3 0x1100090 kqread syslogd 38224 457077 1 0 3 0x100082 sbwait syslogd 45901 412242 1 0 3 0x100080 kqread resolvd 92001 144104 60267 77 3 0x100092 kqread dhcpleased 2329 206361 60267 77 3 0x100092 kqread dhcpleased 60267 124016 1 0 3 0x80 kqread dhcpleased 69338 122104 0 0 3 0x14200 bored smr 49514 27030 0 0 2 0x14200 zerothread 22334 159021 0 0 3 0x14200 aiodoned aiodoned 65289 428271 0 0 3 0x14200 syncer update 4897 1764 0 0 3 0x14200 cleaner cleaner 97762 241722 0 0 3 0x14200 reaper reaper 30865 177611 0 0 3 0x14200 pgdaemon pagedaemon 39336 64983 0 0 3 0x14200 bored viomb 16623 187755 0 0 3 0x40014200 acpi0 acpi0 62162 296036 0 0 3 0x14200 bored softnet0 51878 329203 0 0 3 0x14200 smrbar systqmp 90144 342982 0 0 3 0x14200 bored systq 44158 345725 0 0 3 0x40014200 tmoslp softclock 95356 391503 0 0 3 0x40014200 idle0 1 148561 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 10204 11047K 12107K 166960K 11907 0 pcb 17 13K 14K 166960K 154 0 rtable 158 5K 7K 166960K 347 0 pf 37 14K 17K 166960K 91 0 ifaddr 40 7K 8K 166960K 82 0 ifgroup 51 2K 2K 166960K 113 0 sysctl 3 1K 9K 166960K 8 0 counters 34 17K 18K 166960K 129 0 ioctlops 0 0K 4K 166960K 196 0 iov 0 0K 24K 166960K 33 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1398 88K 89K 166960K 1805 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 16 0 dirhash 12 2K 2K 166960K 24 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 17 61K 89K 166960K 617 0 sigio 0 0K 0K 166960K 14 0 proc 60 59K 108K 166960K 556 0 subproc 72 4K 4K 166960K 81 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 59 0 in_multi 81 5K 7K 166960K 143 0 ether_multi 1 0K 0K 166960K 8 0 mrt 2 0K 0K 166960K 12 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 259 1155K 1155K 166960K 259 0 exec 0 0K 1K 166960K 409 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 222 151K 165K 166960K 6734 0 UVM aobj 20 2K 2K 166960K 23 0 pinsyscall 38 76K 92K 166960K 1669 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 39 0 NDP 11 0K 2K 166960K 50 0 temp 53 8642K 8711K 166960K 18767 0 kqueue 15 24K 27K 166960K 125 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 120 102 0 98 2 0 2 2 0 8 1 rtentry 136 130 0 63 4 0 4 4 0 8 0 unpcb 144 808 0 793 8 0 8 8 0 8 7 syncache 336 3 0 3 1 0 1 1 0 8 1 tcpcb 736 135 0 131 1 0 1 1 0 8 0 arp 96 14 0 5 1 0 1 1 0 8 0 ipq 40 2 0 0 1 0 1 1 0 8 0 ipqe 40 3 0 1 1 0 1 1 0 8 0 inpcb 328 550 0 543 7 0 7 7 0 8 6 ip6q 72 4 0 2 1 0 1 1 0 8 0 ip6af 40 6 0 4 1 0 1 1 0 8 0 nd6 112 24 0 10 1 0 1 1 0 8 0 pkpcb 40 3 0 3 1 0 1 1 0 8 1 kcovpl 48 9 0 1 1 0 1 1 0 8 0 mppekey 1024 1 0 1 1 0 1 1 0 8 1 ppxss 1072 89 0 87 1 0 1 1 0 8 0 pppxif 1384 6 0 4 1 0 1 1 0 8 0 pfstscr 40 3 0 3 1 0 1 1 0 8 1 pfstitem 24 4 0 0 1 0 1 1 0 8 0 pfstkey 128 11 0 7 1 0 1 1 0 8 0 pfstate 384 6 0 4 1 0 1 1 0 8 0 pfrule 1344 2 0 2 1 0 1 1 0 8 1 rttmr 136 3 0 3 1 0 1 1 0 8 1 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 676 0 320 30 0 30 30 0 8 7 art_table 40 677 0 320 5 0 5 5 0 8 0 art_node 32 130 0 70 1 0 1 1 0 8 0 sysvmsgpl 40 5 0 4 1 0 1 1 0 8 0 semapl 112 14 0 4 1 0 1 1 0 8 0 shmpl 112 20 0 3 1 0 1 1 0 8 0 dirhash 1024 25 0 8 3 0 3 3 0 8 0 dino2pl 256 2554 0 1055 95 0 95 95 0 8 0 ffsino 256 2554 0 1055 95 0 95 95 0 8 0 nchpl 144 3419 0 1733 63 0 63 63 0 8 0 rtmask 32 3 0 3 1 0 1 1 0 8 1 uvmvnodes 80 2831 0 0 58 0 58 58 0 8 0 vnodes 216 2831 0 0 158 0 158 158 0 8 0 namei 1024 12171 0 12171 2 0 2 2 0 8 2 kstatmem 264 64 0 42 2 0 2 2 0 8 0 acpiwqpl 32 33 0 33 1 0 1 1 1 8 1 scsiplug 72 3 0 3 1 0 1 1 0 8 1 scxspl 216 10928 0 10928 8 0 8 8 1 8 8 plimitpl 152 221 0 205 1 0 1 1 0 8 0 sigapl 424 891 0 848 6 0 6 6 0 8 0 knotepl 120 23232 0 23154 20 3 17 17 0 8 11 kqueuepl 184 279 0 201 4 0 4 4 0 8 0 pipepl 304 156 0 129 3 0 3 3 0 8 0 fdescpl 448 877 0 848 5 0 5 5 0 8 1 filepl 120 5772 0 5496 14 0 14 14 0 8 5 lockfpl 104 263 0 261 1 0 1 1 0 8 0 lockfspl 48 68 0 66 1 0 1 1 0 8 0 sessionpl 144 23 0 15 1 0 1 1 0 8 0 pgrppl 48 44 0 28 1 0 1 1 0 8 0 ucredpl 104 833 0 822 1 0 1 1 0 8 0 zombiepl 144 850 0 848 1 0 1 1 0 8 0 processpl 1152 891 0 848 4 0 4 4 0 8 0 procpl 664 1613 0 1560 6 0 6 6 0 8 1 sosppl 168 3 0 3 1 0 1 1 0 8 1 sockpl 552 1476 0 1449 17 7 10 17 0 8 8 mcl64k 65536 44 0 44 1 0 1 1 0 8 1 mcl12k 12288 1 0 1 1 0 1 1 0 8 1 mcl8k 8192 9 0 9 1 0 1 1 0 8 1 mcl4k 4096 3073 0 3016 13 0 13 13 0 8 5 mcl2k 2048 935 0 931 5 0 5 5 0 8 4 mtagpl 96 4 0 4 1 0 1 1 0 8 1 mbufpl 256 9389 0 9233 17 0 17 17 0 8 3 bufpl 280 3710 0 120 257 0 257 257 0 8 0 anonpl 24 135929 0 132787 34 0 34 34 0 187 8 amapchunkpl 152 21813 0 21337 28 0 28 28 0 158 8 amappl16 200 2145 0 2113 5 0 5 5 0 8 1 amappl14 184 179 0 169 1 0 1 1 0 8 0 amappl13 176 6 0 6 1 0 1 1 0 8 1 amappl12 168 1500 0 1471 3 0 3 3 0 8 1 amappl11 160 44 0 34 1 0 1 1 0 8 0 amappl10 152 6 0 6 1 0 1 1 0 8 1 amappl9 144 275 0 275 1 0 1 1 0 8 1 amappl8 136 21 0 19 1 0 1 1 0 8 0 amappl7 128 99 0 89 1 0 1 1 0 8 0 amappl6 120 190 0 186 1 0 1 1 0 8 0 amappl5 112 115 0 109 1 0 1 1 0 8 0 amappl4 104 264 0 247 1 0 1 1 0 8 0 amappl3 96 3835 0 3744 3 0 3 3 0 8 0 amappl2 88 1114 0 1042 2 0 2 2 0 8 0 amappl1 80 9961 0 9413 13 0 13 13 0 8 1 amappl 88 5996 0 5838 5 0 5 5 0 92 1 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 128 254 0 254 1 0 1 1 0 8 1 dma64 64 7 0 7 1 0 1 1 0 8 1 dma32 32 8 0 8 1 0 1 1 0 8 1 dma16 16 19 0 18 1 0 1 1 0 8 0 aobjpl 72 22 0 3 1 0 1 1 0 8 0 uaddrrnd 24 877 0 848 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 877 0 848 1 0 1 1 0 8 0 vmmpekpl 168 8058 0 8018 3 0 3 3 0 8 0 vmmpepl 168 59268 0 57414 85 0 85 85 0 357 1 vmsppl 368 876 0 848 4 0 4 4 0 8 1 rwobjpl 40 19793 0 16086 38 0 38 38 0 8 0 pdppl 4096 1760 0 1696 96 30 66 78 0 8 2 pvpl 32 378342 0 369979 104 0 104 104 0 265 23 pmappl 216 876 0 848 2 0 2 2 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 374 0 30 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(ffffffff83337325) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff83379585,ffffffff833d39ae,3b9,ffffffff833ace54) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c95ab48,ffffffff8332da66) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c95ab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002a7abca0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800031506c20) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd807e2b7cb0,1,fffffd8007bfb680,ffff80002a7abca0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd805f4f31e8,ffff80002a7abca0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805f4f31e8,ffff80002a7abca0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805f4f31e8,ffff80002a7abca0) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd805f4f31e8,ffff80002a7abca0) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7abca0) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7abca0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7abca0,ffff800031506f80,ffff800031506ed0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800031506f80) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800031506f80) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72a15b136980, 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(ffffffff83337325) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff83379585,ffffffff833d39ae,3b9,ffffffff833ace54) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c95ab48,ffffffff8332da66) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c95ab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80002a7abca0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff800031506c20) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd807e2b7cb0,1,fffffd8007bfb680,ffff80002a7abca0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd805f4f31e8,ffff80002a7abca0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805f4f31e8,ffff80002a7abca0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805f4f31e8,ffff80002a7abca0) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd805f4f31e8,ffff80002a7abca0) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80002a7abca0) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80002a7abca0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80002a7abca0,ffff800031506f80,ffff800031506ed0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff800031506f80) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff800031506f80) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72a15b136980, count: -16