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(ffffffff8333d57e) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff83378eda,ffffffff833d5d1b,3b7,ffffffff833af85d) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9b30b0,ffffffff83331335) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80003c9b30a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80003c972028) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003153cdf0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805eba08b8,1,fffffd8007bfb820,ffff80003c972028) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd805f8fb960,ffff80003c972028) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805f8fb960,ffff80003c972028) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805f8fb960,ffff80003c972028) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd805f8fb960,ffff80003c972028) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003c972028) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003c972028,0,0,3) at exit1+0x576 sys/kern/kern_exit.c:215 proc_suspend_check_locked(ffff80003c972028,0) at proc_suspend_check_locked+0x45a sys/kern/kern_sig.c:2235 end trace frame: 0xffff80003153d130, 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(ffffffff8333d57e) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff83378eda,ffffffff833d5d1b,3b7,ffffffff833af85d) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9b30b0,ffffffff83331335) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80003c9b30a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80003c972028) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003153cdf0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805eba08b8,1,fffffd8007bfb820,ffff80003c972028) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd805f8fb960,ffff80003c972028) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805f8fb960,ffff80003c972028) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805f8fb960,ffff80003c972028) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd805f8fb960,ffff80003c972028) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003c972028) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003c972028,0,0,3) at exit1+0x576 sys/kern/kern_exit.c:215 proc_suspend_check_locked(ffff80003c972028,0) at proc_suspend_check_locked+0x45a sys/kern/kern_sig.c:2235 userret(ffff80003c972028) at userret+0x8c proc_suspend_check sys/kern/kern_sig.c:-1 [inline] userret(ffff80003c972028) at userret+0x8c sys/kern/kern_sig.c:2194 syscall(ffff80003153d200) at syscall+0xa56 mi_syscall_return sys/sys/syscall_mi.h:203 [inline] syscall(ffff80003153d200) at syscall+0xa56 sys/arch/amd64/amd64/trap.c:769 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7339747ad080, count: -17 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003153cbd0 rbx 0 rdx 0 rcx 0 rax 0xffff80003c972028 r8 0x101010101010101 r9 0x8080808080808080 r10 0xa3e940728f4b3e0a r11 0x80495ea8acf4c13c r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff81a58635 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003153cbc0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=215513 pid=36886 tcnt=0 stat=onproc flags process=1008 proc=82000 runpri=32, usrpri=72, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80003c973780 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80002a822d10,0xffff80002a822fb8 process=0xffff80003c988930 user=0xffff800031538000, vmspace=0xfffffd806ba61740 estcpu=22, cpticks=2, pctcpu=0.0, user=0, sys=2, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 27557 393788 23688 0 2 0 syz-executor 27557 446956 23688 0 3 0x4000080 kqpoll syz-executor 27557 199107 23688 0 2 0x4000000 syz-executor 97045 519438 65111 0 2 0 syz-executor 97045 171248 65111 0 3 0x4000000 smrbar syz-executor 97045 425126 65111 0 3 0x4000000 inode syz-executor 97045 361640 65111 0 2 0x4000000 syz-executor 99712 183654 28958 0 3 0x80 fsleep syz-executor 99712 185630 28958 0 3 0x4000080 fifor syz-executor 99712 55835 28958 0 3 0x4000080 fifor syz-executor 10191 450163 97064 0 3 0x80 fsleep syz-executor 10191 384018 97064 0 3 0x4000080 sbwait syz-executor 83981 58006 25319 0 3 0x80 fsleep syz-executor 83981 413624 25319 0 3 0x4000080 kqread syz-executor 95790 319787 11931 0 3 0x80 fsleep syz-executor 95790 267523 11931 0 3 0x4000080 msgwait syz-executor 83729 276800 0 0 3 0x14200 bored sosplice 65111 69395 42678 0 3 0x82 nanoslp syz-executor 23688 300918 42678 0 2 0xc82 syz-executor 43309 233391 42678 0 3 0x82 wait syz-executor 97064 234875 42678 0 2 0xc82 syz-executor 25319 6507 42678 0 2 0xc82 syz-executor 11931 368051 42678 0 2 0xc82 syz-executor 28958 97221 42678 0 3 0x82 nanoslp syz-executor 69474 347462 42678 0 2 0x2 syz-executor 42678 180633 86284 0 3 0x82 kqread syz-executor 86284 405023 54073 0 3 0x10008a sigsusp ksh 54073 50442 25990 0 3 0x98 kqread sshd-session 25990 228949 82324 0 3 0x92 kqread sshd-session 45999 332595 1 0 3 0x100083 ttyopn getty 82324 73068 1 0 3 0x88 kqread sshd 48241 360826 78115 73 3 0x1100090 kqread syslogd 78115 331688 1 0 3 0x100082 sbwait syslogd 4887 279402 1 0 3 0x100080 kqread resolvd 39735 369827 96654 77 3 0x100092 kqread dhcpleased 75236 97722 96654 77 3 0x100092 kqread dhcpleased 96654 184539 1 0 3 0x80 kqread dhcpleased 33089 39153 0 0 3 0x14200 bored smr 31942 339757 0 0 2 0x14200 zerothread 61435 81321 0 0 3 0x14200 aiodoned aiodoned 11419 482899 0 0 3 0x14200 syncer update 67287 304252 0 0 3 0x14200 cleaner cleaner 81413 171410 0 0 3 0x14200 reaper reaper 82105 456438 0 0 3 0x14200 pgdaemon pagedaemon 62624 124285 0 0 3 0x14200 bored viomb 36742 336560 0 0 3 0x40014200 acpi0 acpi0 29468 183904 0 0 3 0x14200 bored softnet7 47398 417366 0 0 3 0x14200 bored softnet6 71284 419309 0 0 3 0x14200 bored softnet5 58494 513172 0 0 3 0x14200 bored softnet4 29301 451251 0 0 3 0x14200 bored softnet3 30237 196655 0 0 3 0x14200 bored softnet2 21517 76213 0 0 3 0x14200 bored softnet1 90135 516808 0 0 3 0x14200 bored softnet0 41279 76712 0 0 3 0x14200 bored systqmp 71515 214142 0 0 3 0x14200 bored systq 81289 4031 0 0 2 0x40014200 softclock 33039 202411 0 0 3 0x40014200 idle0 1 390421 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 10196 11110K 11337K 166960K 11656 0 pcb 18 13K 14K 166960K 98 0 rtable 197 7K 7K 166960K 301 0 pf 42 15K 22K 166960K 76 0 ifaddr 45 7K 8K 166960K 61 0 ifgroup 61 2K 2K 166960K 86 0 sysctl 3 1K 9K 166960K 8 0 counters 37 18K 18K 166960K 49 0 ioctlops 0 0K 4K 166960K 77 0 iov 0 0K 12K 166960K 74 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1406 88K 88K 166960K 1637 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 8 0K 1K 166960K 9 0 dirhash 12 2K 2K 166960K 21 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 18 65K 97K 166960K 329 0 sigio 0 0K 0K 166960K 3 0 proc 60 59K 124K 166960K 481 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 24 0 in_multi 99 7K 7K 166960K 110 0 ether_multi 1 0K 0K 166960K 2 0 mrt 1 0K 0K 166960K 1 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 79 360K 360K 166960K 79 0 exec 0 0K 1K 166960K 365 0 fusefs mount 1 32K 32K 166960K 1 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 243 152K 160K 166960K 4534 0 UVM aobj 9 2K 2K 166960K 11 0 pinsyscall 39 78K 96K 166960K 1361 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 10 0 NDP 14 0K 2K 166960K 38 0 temp 40 8635K 8714K 166960K 9822 0 kqueue 15 22K 28K 166960K 64 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 50 0 47 1 0 1 1 0 8 0 rtentry 136 101 0 18 4 0 4 4 0 8 0 unpcb 144 162 0 143 2 0 2 2 0 8 1 syncache 336 3 0 3 1 0 1 1 0 8 1 tcpcb 736 40 0 36 1 0 1 1 0 8 0 arp 88 11 0 1 1 0 1 1 0 8 0 ipq 40 1 0 1 1 0 1 1 0 8 1 ipqe 40 2 0 2 1 0 1 1 0 8 1 inpcb 328 220 0 212 4 0 4 4 0 8 3 ip6q 72 2 0 0 1 0 1 1 0 8 0 ip6af 40 3 0 1 1 0 1 1 0 8 0 nd6 104 17 0 1 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 11 0 8 1 0 1 1 0 8 0 pppxif 1384 3 0 1 1 0 1 1 0 8 0 pfstscr 40 5 0 5 1 0 1 1 0 8 1 pfrktable 1344 4 0 1 1 0 1 1 0 8 0 pfanchor 1288 3 0 0 1 0 1 1 0 8 0 pftag 88 2 0 0 1 0 1 1 0 8 0 pfstkey 128 6 0 6 1 0 1 1 0 8 1 pfstate 384 3 0 3 1 0 1 1 0 8 1 pfrule 1344 6 0 5 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 495 0 65 30 0 30 30 0 8 1 art_table 40 496 0 65 5 0 5 5 0 8 0 art_node 32 101 0 28 1 0 1 1 0 8 0 semupl 112 2 0 2 1 0 1 1 0 8 1 semapl 112 6 0 0 1 0 1 1 0 8 0 shmpl 112 8 0 2 1 0 1 1 0 8 0 dirhash 1024 23 0 6 3 0 3 3 0 8 0 dino2pl 256 1987 0 482 95 0 95 95 0 8 0 ffsino 256 1987 0 482 95 0 95 95 0 8 0 nchpl 144 2420 0 731 63 0 63 63 0 8 0 uvmvnodes 80 2229 0 0 46 0 46 46 0 8 0 vnodes 216 2229 0 0 124 0 124 124 0 8 0 namei 1024 7620 0 7618 2 0 2 2 0 8 1 pfiaddrpl 120 1 0 0 1 0 1 1 0 8 0 kstatmem 264 44 0 16 2 0 2 2 0 8 0 scxspl 216 8598 0 8598 8 0 8 8 1 8 8 plimitpl 152 61 0 44 1 0 1 1 0 8 0 sigapl 424 615 0 564 7 0 7 7 0 8 1 knotepl 120 9991 0 9943 2 0 2 2 0 8 0 kqueuepl 184 89 0 76 1 0 1 1 0 8 0 pipepl 304 113 0 86 3 0 3 3 0 8 0 fdescpl 448 593 0 563 5 0 5 5 0 8 1 filepl 120 2644 0 2421 9 0 9 9 0 8 1 lockfpl 104 96 0 93 1 0 1 1 0 8 0 lockfspl 48 45 0 42 1 0 1 1 0 8 0 sessionpl 144 21 0 13 1 0 1 1 0 8 0 pgrppl 48 30 0 14 1 0 1 1 0 8 0 ucredpl 104 354 0 342 1 0 1 1 0 8 0 zombiepl 144 566 0 564 1 0 1 1 0 8 0 processpl 1168 615 0 564 5 0 5 5 0 8 1 procpl 664 906 0 845 6 0 6 6 0 8 0 sockpl 552 438 0 408 5 0 5 5 0 8 2 mcl64k 65536 26 0 26 3 0 3 3 0 8 3 mcl12k 12288 1 0 1 1 0 1 1 0 8 1 mcl9k 9216 2 0 2 1 0 1 1 0 8 1 mcl8k 8192 10 0 10 1 0 1 1 0 8 1 mcl4k 4096 2699 0 2649 13 0 13 13 0 8 6 mcl2k 2048 462 0 460 2 0 2 2 0 8 1 mtagpl 96 75 0 69 1 0 1 1 0 8 0 mbufpl 256 6113 0 5940 15 0 15 15 0 8 2 bufpl 280 3396 0 118 235 0 235 235 0 8 0 anonpl 24 126764 0 123514 57 0 57 57 0 187 28 amapchunkpl 152 13956 0 13424 26 0 26 26 0 158 5 amappl16 200 2503 0 2475 17 5 12 14 0 8 8 amappl15 192 7 0 7 1 0 1 1 0 8 1 amappl14 184 108 0 98 1 0 1 1 0 8 0 amappl13 176 5 0 5 1 0 1 1 0 8 1 amappl12 168 1250 0 1220 3 0 3 3 0 8 1 amappl11 160 42 0 32 1 0 1 1 0 8 0 amappl10 152 5 0 5 1 0 1 1 0 8 1 amappl9 144 252 0 252 1 0 1 1 0 8 1 amappl8 136 46 0 45 1 0 1 1 0 8 0 amappl7 128 98 0 88 1 0 1 1 0 8 0 amappl6 120 170 0 167 1 0 1 1 0 8 0 amappl5 112 114 0 107 1 0 1 1 0 8 0 amappl4 104 264 0 248 1 0 1 1 0 8 0 amappl3 96 2465 0 2345 3 0 3 3 0 8 0 amappl2 88 640 0 586 2 0 2 2 0 8 0 amappl1 80 8609 0 8062 13 0 13 13 0 8 1 amappl 88 3864 0 3684 4 0 4 4 0 92 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 10 0 2 1 0 1 1 0 8 0 uaddrrnd 24 593 0 563 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 593 0 563 1 0 1 1 0 8 0 vmmpekpl 168 5985 0 5961 2 0 2 2 0 8 0 vmmpepl 168 44281 0 42377 93 0 93 93 0 357 6 vmsppl 368 592 0 563 4 0 4 4 0 8 1 rwobjpl 40 16577 0 13481 32 0 32 32 0 8 0 pdppl 4096 1193 0 1126 97 30 67 83 0 8 0 pvpl 32 297374 0 288532 134 0 134 134 0 265 49 pmappl 216 592 0 563 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 376 0 30 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(ffffffff8333d57e) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff83378eda,ffffffff833d5d1b,3b7,ffffffff833af85d) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9b30b0,ffffffff83331335) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80003c9b30a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80003c972028) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003153cdf0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805eba08b8,1,fffffd8007bfb820,ffff80003c972028) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd805f8fb960,ffff80003c972028) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805f8fb960,ffff80003c972028) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805f8fb960,ffff80003c972028) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd805f8fb960,ffff80003c972028) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003c972028) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003c972028,0,0,3) at exit1+0x576 sys/kern/kern_exit.c:215 proc_suspend_check_locked(ffff80003c972028,0) at proc_suspend_check_locked+0x45a sys/kern/kern_sig.c:2235 userret(ffff80003c972028) at userret+0x8c proc_suspend_check sys/kern/kern_sig.c:-1 [inline] userret(ffff80003c972028) at userret+0x8c sys/kern/kern_sig.c:2194 syscall(ffff80003153d200) at syscall+0xa56 mi_syscall_return sys/sys/syscall_mi.h:203 [inline] syscall(ffff80003153d200) at syscall+0xa56 sys/arch/amd64/amd64/trap.c:769 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7339747ad080, count: -17 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8333d57e) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff83378eda,ffffffff833d5d1b,3b7,ffffffff833af85d) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9b30b0,ffffffff83331335) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(205b9a,ffff80003c9b30a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff80003c972028) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003153cdf0) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805eba08b8,1,fffffd8007bfb820,ffff80003c972028) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd805f8fb960,ffff80003c972028) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd805f8fb960,ffff80003c972028) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd805f8fb960,ffff80003c972028) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd805f8fb960,ffff80003c972028) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff80003c972028) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff80003c972028,0,0,3) at exit1+0x576 sys/kern/kern_exit.c:215 proc_suspend_check_locked(ffff80003c972028,0) at proc_suspend_check_locked+0x45a sys/kern/kern_sig.c:2235 userret(ffff80003c972028) at userret+0x8c proc_suspend_check sys/kern/kern_sig.c:-1 [inline] userret(ffff80003c972028) at userret+0x8c sys/kern/kern_sig.c:2194 syscall(ffff80003153d200) at syscall+0xa56 mi_syscall_return sys/sys/syscall_mi.h:203 [inline] syscall(ffff80003153d200) at syscall+0xa56 sys/arch/amd64/amd64/trap.c:769 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7339747ad080, count: -17