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(ffffffff833409fb) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a9b6,ffffffff833db592,3b9,ffffffff833b56b0) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003a5355a8,ffffffff8333346e) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003a5355a0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80003c94ba10) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80002ccfadc0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806b770ce8,1,fffffd8007bfb6e8,ffff80003c94ba10) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b5b1a68,ffff80003c94ba10) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b5b1a68,ffff80003c94ba10) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806b5b1a68,ffff80003c94ba10) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b5b1a68,ffff80003c94ba10) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003c94ba10) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003c94ba10,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003c94ba10,ffff80002ccfb120,ffff80002ccfb070) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff80002ccfb110, 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(ffffffff833409fb) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a9b6,ffffffff833db592,3b9,ffffffff833b56b0) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003a5355a8,ffffffff8333346e) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003a5355a0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80003c94ba10) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80002ccfadc0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806b770ce8,1,fffffd8007bfb6e8,ffff80003c94ba10) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b5b1a68,ffff80003c94ba10) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b5b1a68,ffff80003c94ba10) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806b5b1a68,ffff80003c94ba10) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b5b1a68,ffff80003c94ba10) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003c94ba10) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003c94ba10,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003c94ba10,ffff80002ccfb120,ffff80002ccfb070) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80002ccfb120) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80002ccfb120) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7cd0def4a610, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80002ccfaba0 rbx 0 rdx 0 rcx 0 rax 0xffff80003c94ba10 r8 0x101010101010101 r9 0x8080808080808080 r10 0x92a8a0e725992465 r11 0x9e9b08b93b080ecd r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff821e3365 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80002ccfab90 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=352199 pid=22872 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80003c94ba10 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80003c94ad18,0xffff80002a7aaa88 process=0xffff8000ffff9218 user=0xffff80002ccf6000, vmspace=0xfffffd806ba422f0 estcpu=36, cpticks=7, pctcpu=0.0, user=0, sys=2, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 69604 520205 73504 0 3 0x80 nanoslp syz-executor 69604 1098 73504 0 3 0x4000000 smrbar syz-executor 69604 503590 73504 0 3 0x4000080 fsleep syz-executor 71339 506923 87649 0 2 0 syz-executor 71339 23403 87649 0 3 0x4000080 fsleep syz-executor 9758 205600 39174 0 2 0 syz-executor 9758 231780 39174 0 3 0x4000000 smrbar syz-executor 9758 398597 39174 0 3 0x4000080 fsleep syz-executor 32451 484726 86972 0 2 0xc80 syz-executor 32451 135664 86972 0 3 0x4000080 kqread syz-executor 32451 60417 86972 0 3 0x4000080 kqread syz-executor 32451 304146 86972 0 3 0x4000080 fsleep syz-executor 73504 61950 60491 0 2 0xc82 syz-executor 22446 30878 0 0 3 0x14200 bored sosplice 19153 152067 0 0 3 0x14200 acct acct 87649 86259 60491 0 2 0xc82 syz-executor 96907 485418 1 0 3 0x100083 ttyin getty 86493 512529 60491 0 2 0xc82 syz-executor 62442 516161 60491 0 3 0x82 wait syz-executor 60158 372391 60491 0 3 0x82 wait syz-executor 86972 111391 60491 0 2 0xc82 syz-executor 39174 377716 60491 0 3 0x82 nanoslp syz-executor 33346 426189 60491 0 2 0x2 syz-executor 60491 293608 55498 0 3 0x82 kqread syz-executor 55498 229098 2854 0 3 0x10008a sigsusp ksh 2854 343867 48768 0 3 0x98 kqread sshd-session 48768 90485 40981 0 3 0x92 kqread sshd-session 40981 367916 1 0 3 0x88 kqread sshd 89663 162057 2186 73 3 0x1100090 kqread syslogd 2186 189480 1 0 3 0x100082 sbwait syslogd 9796 1943 1 0 3 0x100080 kqread resolvd 29321 448657 17512 77 3 0x100092 kqread dhcpleased 32136 381300 17512 77 3 0x100092 kqread dhcpleased 17512 120268 1 0 3 0x80 kqread dhcpleased 33177 432148 0 0 3 0x14200 bored smr 10685 382982 0 0 2 0x14200 zerothread 81617 521272 0 0 3 0x14200 aiodoned aiodoned 42575 518071 0 0 3 0x14200 syncer update 4104 127605 0 0 3 0x14200 cleaner cleaner 23657 64037 0 0 3 0x14200 reaper reaper 72432 164446 0 0 3 0x14200 pgdaemon pagedaemon 54465 446147 0 0 3 0x14200 bored viomb 18521 290564 0 0 3 0x40014200 acpi0 acpi0 63054 513644 0 0 3 0x14200 bored softnet0 36072 468432 0 0 3 0x14200 bored systqmp 95877 178029 0 0 3 0x14200 bored systq 79386 402799 0 0 3 0x40014200 tmoslp softclock 11904 413381 0 0 3 0x40014200 idle0 1 317153 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 10201 11202K 11239K 166960K 11609 0 pcb 18 12K 12K 166960K 66 0 rtable 190 6K 7K 166960K 345 0 pf 37 14K 14K 166960K 61 0 ifaddr 45 7K 8K 166960K 71 0 ifgroup 61 2K 2K 166960K 90 0 sysctl 3 1K 9K 166960K 9 0 counters 37 18K 18K 166960K 50 0 ioctlops 0 0K 4K 166960K 170 0 iov 0 0K 12K 166960K 16 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1342 84K 85K 166960K 1592 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 10 0K 0K 166960K 13 0 dirhash 12 2K 2K 166960K 15 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 17 61K 89K 166960K 434 0 sigio 0 0K 0K 166960K 4 0 proc 61 59K 108K 166960K 569 0 subproc 72 4K 4K 166960K 90 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 63 0 in_multi 99 7K 7K 166960K 143 0 ether_multi 1 0K 0K 166960K 8 0 mrt 0 0K 0K 166960K 4 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 103 466K 466K 166960K 103 0 exec 0 0K 1K 166960K 431 0 fusefs mount 1 32K 32K 166960K 1 0 pfkey data 0 0K 0K 166960K 3 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 228 151K 165K 166960K 5329 0 UVM aobj 8 2K 2K 166960K 10 0 pinsyscall 38 76K 93K 166960K 1517 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 20 0 NDP 14 0K 1K 166960K 46 0 temp 49 8633K 8697K 166960K 23350 0 kqueue 15 22K 30K 166960K 88 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 58 0 55 1 0 1 1 0 8 0 rtentry 136 123 0 41 4 0 4 4 0 8 0 unpcb 144 378 0 362 4 0 4 4 0 8 3 syncache 336 5 0 5 1 0 1 1 0 8 1 tcpcb 736 182 0 172 7 0 7 7 0 8 6 arp 96 13 0 3 1 0 1 1 0 8 0 ipq 40 1 0 0 1 0 1 1 0 8 0 ipqe 40 2 0 1 1 0 1 1 0 8 0 inpcb 328 376 0 359 7 0 7 7 0 8 5 nd6 112 23 0 7 1 0 1 1 0 8 0 pkpcb 40 5 0 4 1 0 1 1 0 8 0 kcovpl 48 10 0 2 1 0 1 1 0 8 0 mppekey 1024 1 0 1 1 0 1 1 0 8 1 ppxss 1072 13 0 10 1 0 1 1 0 8 0 pppxif 1384 2 0 0 1 0 1 1 0 8 0 pfrule 1344 3 0 2 1 0 1 1 0 8 0 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 588 0 154 29 0 29 29 0 8 1 art_table 40 590 0 154 5 0 5 5 0 8 0 art_node 32 123 0 51 1 0 1 1 0 8 0 sysvmsgpl 40 133 0 131 1 0 1 1 0 8 0 semapl 112 11 0 3 1 0 1 1 0 8 0 shmpl 112 7 0 2 1 0 1 1 0 8 0 dirhash 1024 19 0 2 3 0 3 3 0 8 0 dino2pl 256 2098 0 585 95 0 95 95 0 8 0 ffsino 256 2098 0 585 95 0 95 95 0 8 0 nchpl 144 2675 0 979 63 0 63 63 0 8 0 uvmvnodes 80 2299 0 0 47 0 47 47 0 8 0 vnodes 216 2299 0 0 128 0 128 128 0 8 0 namei 1024 9138 0 9138 2 0 2 2 0 8 2 kstatmem 264 50 0 22 2 0 2 2 0 8 0 scsiplug 72 2 0 2 1 0 1 1 0 8 1 scxspl 216 11613 0 11613 8 0 8 8 1 8 8 plimitpl 152 83 0 66 1 0 1 1 0 8 0 sigapl 424 709 0 665 6 0 6 6 0 8 0 knotepl 120 17298 0 17249 12 2 10 12 0 8 8 kqueuepl 184 116 0 103 1 0 1 1 0 8 0 pipepl 304 126 0 97 3 0 3 3 0 8 0 fdescpl 448 693 0 664 5 0 5 5 0 8 1 filepl 120 3904 0 3660 10 0 10 10 0 8 0 lockfpl 104 256 0 252 2 0 2 2 0 8 1 lockfspl 48 52 0 48 1 0 1 1 0 8 0 sessionpl 144 25 0 17 1 0 1 1 0 8 0 pgrppl 48 102 0 86 1 0 1 1 0 8 0 ucredpl 104 404 0 392 1 0 1 1 0 8 0 zombiepl 144 668 0 665 1 0 1 1 0 8 0 processpl 1152 709 0 665 4 0 4 4 0 8 0 procpl 664 1155 0 1103 6 0 6 6 0 8 0 sosppl 168 2 0 2 1 0 1 1 0 8 1 sockpl 552 831 0 794 8 0 8 8 0 8 5 mcl64k 65536 18 0 18 1 0 1 1 0 8 1 mcl16k 16384 1 0 1 1 0 1 1 0 8 1 mcl9k 9216 1 0 1 1 0 1 1 0 8 1 mcl8k 8192 6 0 6 1 0 1 1 0 8 1 mcl4k 4096 2798 0 2747 14 0 14 14 0 8 6 mcl2k2 2112 1 0 1 1 0 1 1 0 8 1 mcl2k 2048 696 0 693 2 0 2 2 0 8 1 mtagpl 96 6 0 6 1 0 1 1 0 8 1 mbufpl 256 7135 0 6963 13 0 13 13 0 8 0 bufpl 280 4824 0 120 336 0 336 336 0 8 0 anonpl 24 139951 0 136740 69 0 69 69 0 187 30 amapchunkpl 152 16967 0 16480 26 0 26 26 0 158 5 amappl16 200 2923 0 2897 27 17 10 27 0 8 7 amappl15 192 20 0 20 1 0 1 1 0 8 1 amappl14 184 111 0 101 1 0 1 1 0 8 0 amappl13 176 10 0 10 1 0 1 1 0 8 1 amappl12 168 1334 0 1305 3 0 3 3 0 8 1 amappl11 160 46 0 36 1 0 1 1 0 8 0 amappl10 152 8 0 8 1 0 1 1 0 8 1 amappl9 144 252 0 251 1 0 1 1 0 8 0 amappl8 136 26 0 25 1 0 1 1 0 8 0 amappl7 128 119 0 109 1 0 1 1 0 8 0 amappl6 120 191 0 188 1 0 1 1 0 8 0 amappl5 112 128 0 121 1 0 1 1 0 8 0 amappl4 104 270 0 254 1 0 1 1 0 8 0 amappl3 96 2788 0 2696 3 0 3 3 0 8 0 amappl2 88 925 0 853 2 0 2 2 0 8 0 amappl1 80 9517 0 8974 13 0 13 13 0 8 0 amappl 88 4612 0 4448 5 0 5 5 0 92 1 dma8192 8192 2 0 2 1 0 1 1 0 8 1 dma4096 4096 2 0 2 1 0 1 1 0 8 1 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 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 24 693 0 664 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 693 0 664 1 0 1 1 0 8 0 vmmpekpl 168 6931 0 6880 3 0 3 3 0 8 0 vmmpepl 168 50564 0 48722 104 0 104 104 0 357 17 vmsppl 368 692 0 664 4 0 4 4 0 8 1 rwobjpl 40 18784 0 15632 33 0 33 33 0 8 0 pdppl 4096 1392 0 1328 96 28 68 78 0 8 4 pvpl 32 337255 0 327524 156 0 156 156 0 265 56 pmappl 216 692 0 664 2 0 2 2 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 377 0 28 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(ffffffff833409fb) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a9b6,ffffffff833db592,3b9,ffffffff833b56b0) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003a5355a8,ffffffff8333346e) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003a5355a0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80003c94ba10) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80002ccfadc0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806b770ce8,1,fffffd8007bfb6e8,ffff80003c94ba10) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b5b1a68,ffff80003c94ba10) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b5b1a68,ffff80003c94ba10) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806b5b1a68,ffff80003c94ba10) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b5b1a68,ffff80003c94ba10) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003c94ba10) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003c94ba10,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003c94ba10,ffff80002ccfb120,ffff80002ccfb070) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80002ccfb120) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80002ccfb120) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7cd0def4a610, 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(ffffffff833409fb) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a9b6,ffffffff833db592,3b9,ffffffff833b56b0) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003a5355a8,ffffffff8333346e) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003a5355a0) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80003c94ba10) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80002ccfadc0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806b770ce8,1,fffffd8007bfb6e8,ffff80003c94ba10) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b5b1a68,ffff80003c94ba10) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b5b1a68,ffff80003c94ba10) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806b5b1a68,ffff80003c94ba10) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b5b1a68,ffff80003c94ba10) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003c94ba10) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003c94ba10,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003c94ba10,ffff80002ccfb120,ffff80002ccfb070) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80002ccfb120) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80002ccfb120) at syscall+0x962 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7cd0def4a610, count: -16