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(ffffffff8335dc0b) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8339b96a,ffffffff833f502d,3b9,ffffffff833ce89b) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c97f0b0,ffffffff83353fb9) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c97f0a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff800035d1efb8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80002a7b1600) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c994488,1,fffffd8007bfb820,ffff800035d1efb8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806ab69000,ffff800035d1efb8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806ab69000,ffff800035d1efb8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806ab69000,ffff800035d1efb8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806ab69000,ffff800035d1efb8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff800035d1efb8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff800035d1efb8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff800035d1efb8,ffff80002a7b1960,ffff80002a7b18b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff80002a7b1950, 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(ffffffff8335dc0b) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8339b96a,ffffffff833f502d,3b9,ffffffff833ce89b) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c97f0b0,ffffffff83353fb9) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c97f0a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff800035d1efb8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80002a7b1600) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c994488,1,fffffd8007bfb820,ffff800035d1efb8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806ab69000,ffff800035d1efb8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806ab69000,ffff800035d1efb8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806ab69000,ffff800035d1efb8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806ab69000,ffff800035d1efb8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff800035d1efb8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff800035d1efb8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff800035d1efb8,ffff80002a7b1960,ffff80002a7b18b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80002a7b1960) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80002a7b1960) at syscall+0x962 sys/arch/amd64/amd64/trap.c:765 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x6fe9804f05b0, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80002a7b13e0 rbx 0 rdx 0 rcx 0 rax 0xffff800035d1efb8 r8 0x101010101010101 r9 0x8080808080808080 r10 0x9e1d8ed04e196c36 r11 0xbd57ed003201780b r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff83168a15 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80002a7b13d0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=304224 pid=75638 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff800035d1efb8 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80003c94aa80,0xffff80003c94b4f0 process=0xffff8000ffff9218 user=0xffff80002a7ac000, vmspace=0xfffffd80685d78b8 estcpu=36, cpticks=6, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 27009 332868 82161 0 2 0 syz-executor 27009 157658 82161 0 3 0x4000080 kqread syz-executor 27009 63325 82161 0 2 0x4000000 syz-executor 18146 85386 40228 0 3 0x80 nanoslp syz-executor 18146 115732 40228 0 3 0x4000000 smrbar syz-executor 92647 74419 86241 0 2 0xc80 syz-executor 92647 25259 86241 0 3 0x4000080 kqread syz-executor 92647 105190 86241 0 3 0x4000080 fsleep syz-executor 7947 290413 47922 0 3 0x80 nanoslp syz-executor 7947 338603 47922 0 3 0x4000080 ttyin syz-executor 7947 386774 47922 0 3 0x4000080 fsleep syz-executor 7947 409976 47922 0 3 0x4000080 fsleep syz-executor 5245 254846 99675 -1 3 0x90 nanoslp syz-executor 5245 246810 99675 -1 3 0x4000090 dtread syz-executor 5245 449527 99675 -1 3 0x4000090 dtread syz-executor 63569 298469 0 0 3 0x14200 acct acct 68752 397856 1 0 3 0x100083 ttyin getty 17368 227181 63485 0 2 0x2 syz-executor 40228 169979 63485 0 3 0x82 nanoslp syz-executor 47922 298480 63485 0 3 0x82 nanoslp syz-executor 86241 161542 63485 0 2 0xc82 syz-executor 39164 88776 63485 0 3 0x82 wait syz-executor 19488 327730 63485 0 2 0xc82 syz-executor 82161 514366 63485 0 3 0x82 nanoslp syz-executor 99675 271230 63485 0 3 0x82 nanoslp syz-executor 63485 209473 46069 0 3 0x82 kqread syz-executor 46069 242333 24818 0 3 0x10008a sigsusp ksh 24818 509466 18455 0 3 0x98 kqread sshd-session 18455 503273 84536 0 3 0x92 kqread sshd-session 84536 413739 1 0 3 0x88 kqread sshd 89167 449706 83074 73 3 0x1100090 kqread syslogd 83074 132075 1 0 3 0x100082 sbwait syslogd 87942 64437 1 0 3 0x100080 kqread resolvd 26915 189360 78400 77 3 0x100092 kqread dhcpleased 31057 449413 78400 77 3 0x100092 kqread dhcpleased 78400 178978 1 0 3 0x80 kqread dhcpleased 75672 230093 0 0 3 0x14200 bored smr 87320 381026 0 0 2 0x14200 zerothread 32672 61717 0 0 3 0x14200 aiodoned aiodoned 67806 209370 0 0 3 0x14200 syncer update 55797 181215 0 0 3 0x14200 cleaner cleaner 81096 59541 0 0 3 0x14200 reaper reaper 14545 433565 0 0 3 0x14200 pgdaemon pagedaemon 813 287810 0 0 3 0x14200 bored viomb 59272 87362 0 0 3 0x40014200 acpi0 acpi0 50231 74980 0 0 3 0x14200 bored softnet0 19764 304486 0 0 3 0x14200 bored systqmp 6711 138968 0 0 3 0x14200 bored systq 72684 465511 0 0 3 0x40014200 tmoslp softclock 64584 165317 0 0 3 0x40014200 idle0 1 153392 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 10227 11233K 11383K 166960K 12042 0 pcb 19 14K 15K 166960K 138 0 rtable 224 9K 9K 166960K 469 0 pf 39 14K 20K 166960K 105 0 ifaddr 41 6K 8K 166960K 77 0 ifgroup 67 2K 2K 166960K 123 0 sysctl 3 1K 9K 166960K 10 0 counters 38 18K 18K 166960K 68 0 ioctlops 0 0K 4K 166960K 145 0 iov 0 0K 24K 166960K 33 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1407 88K 89K 166960K 1938 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 5K 166960K 10 0 VM map 2 1K 1K 166960K 2 0 sem 12 0K 0K 166960K 24 0 dirhash 12 2K 2K 166960K 21 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 17 61K 89K 166960K 654 0 sigio 0 0K 0K 166960K 10 0 proc 60 59K 100K 166960K 526 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 91 0 in_multi 78 5K 7K 166960K 119 0 ether_multi 1 0K 0K 166960K 7 0 mrt 0 0K 0K 166960K 11 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 145 652K 652K 166960K 145 0 exec 0 0K 1K 166960K 446 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 237 160K 174K 166960K 7576 0 UVM aobj 13 2K 2K 166960K 14 0 pinsyscall 38 76K 93K 166960K 1759 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 55 0 NDP 16 0K 2K 166960K 52 0 temp 49 8645K 8738K 166960K 26107 0 kqueue 18 28K 31K 166960K 129 0 SYN cache 2 8K 16K 166960K 3 0 ddb> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle rtpcb 120 216 0 212 5 0 5 5 0 8 4 rtentry 136 133 0 42 4 0 4 4 0 8 0 unpcb 144 464 0 446 6 0 6 6 0 8 5 syncache 336 7 0 7 1 0 1 1 0 8 1 tcpqe 32 3 0 3 1 0 1 1 0 8 1 tcpcb 736 416 0 408 7 0 7 7 0 8 6 arp 96 22 0 7 1 0 1 1 0 8 0 ipq 40 3 0 1 1 0 1 1 0 8 0 ipqe 40 4 0 2 1 0 1 1 0 8 0 inpcb 328 1000 0 985 7 0 7 7 0 8 5 ip6q 72 1 0 1 1 0 1 1 0 8 1 ip6af 40 2 0 2 1 0 1 1 0 8 1 nd6 112 26 0 8 1 0 1 1 0 8 0 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1072 26 0 24 1 0 1 1 0 8 0 pppxif 1384 6 0 4 1 0 1 1 0 8 0 pfanchor 1288 4 0 0 1 0 1 1 0 8 0 pfrule 1344 4 0 3 1 0 1 1 0 8 0 rttmr 136 3 0 3 1 0 1 1 0 8 1 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 571 0 201 29 0 29 29 0 8 4 art_table 40 573 0 201 5 0 5 5 0 8 0 art_node 32 132 0 49 1 0 1 1 0 8 0 sysvmsgpl 40 6 0 6 1 0 1 1 0 8 1 semapl 112 22 0 12 1 0 1 1 0 8 0 shmpl 112 11 0 1 1 0 1 1 0 8 0 dirhash 1024 23 0 6 3 0 3 3 0 8 0 dino2pl 256 2632 0 1128 95 0 95 95 0 8 0 ffsino 256 2632 0 1128 95 0 95 95 0 8 0 nchpl 144 3576 0 1878 64 0 64 64 0 8 0 rtmask 32 5 0 5 1 0 1 1 0 8 1 vnodes 216 3025 0 0 169 0 169 169 0 8 0 namei 1024 11909 0 11909 2 0 2 2 0 8 2 kstatmem 264 70 0 40 3 0 3 3 0 8 1 scsiplug 72 2 0 2 1 0 1 1 0 8 1 scxspl 216 12856 0 12856 8 0 8 8 1 8 8 plimitpl 152 217 0 200 1 0 1 1 0 8 0 sigapl 424 955 0 912 6 0 6 6 0 8 1 knotepl 120 37759 0 37698 23 12 11 17 0 8 8 kqueuepl 184 239 0 219 3 0 3 3 0 8 1 pipepl 304 180 0 152 5 0 5 5 0 8 2 fdescpl 448 936 0 907 5 0 5 5 0 8 1 filepl 120 6163 0 5922 15 0 15 15 0 8 7 lockfpl 104 201 0 198 1 0 1 1 0 8 0 lockfspl 48 91 0 88 1 0 1 1 0 8 0 sessionpl 144 26 0 18 1 0 1 1 0 8 0 pgrppl 48 41 0 25 1 0 1 1 0 8 0 ucredpl 104 1052 0 1039 1 0 1 1 0 8 0 zombiepl 144 914 0 912 1 0 1 1 0 8 0 processpl 1152 955 0 912 4 0 4 4 0 8 0 procpl 664 1775 0 1722 6 0 6 6 0 8 1 sosppl 176 9 0 8 1 0 1 1 0 8 0 sockpl 552 1696 0 1658 16 5 11 15 0 8 8 mcl64k 65536 115 0 115 1 0 1 1 0 8 1 mcl8k 8192 7 0 7 1 0 1 1 0 8 1 mcl4k 4096 3146 0 3092 13 0 13 13 0 8 5 mcl2k 2048 1055 0 1049 3 0 3 3 0 8 1 mtagpl 96 9 0 5 1 0 1 1 0 8 0 mbufpl 256 14441 0 14275 158 132 26 105 0 8 8 bufpl 280 5588 0 121 391 0 391 391 0 8 0 anonpl 24 164778 0 161566 45 0 45 45 0 187 13 amapchunkpl 152 25032 0 24542 30 0 30 30 0 158 10 amappl16 200 2960 0 2929 18 2 16 16 0 8 12 amappl15 192 5 0 5 1 0 1 1 0 8 1 amappl14 184 82 0 82 1 0 1 1 0 8 1 amappl13 176 417 0 415 1 0 1 1 0 8 0 amappl12 168 1297 0 1259 2 0 2 2 0 8 0 amappl11 160 5 0 5 1 0 1 1 0 8 1 amappl10 152 46 0 36 1 0 1 1 0 8 0 amappl9 144 287 0 287 1 0 1 1 0 8 1 amappl8 136 52 0 50 1 0 1 1 0 8 0 amappl7 128 78 0 77 1 0 1 1 0 8 0 amappl6 120 288 0 277 1 0 1 1 0 8 0 amappl5 112 71 0 63 1 0 1 1 0 8 0 amappl4 104 405 0 380 1 0 1 1 0 8 0 amappl3 96 4197 0 4104 3 0 3 3 0 8 0 amappl2 88 1090 0 1018 2 0 2 2 0 8 0 amappl1 80 12209 0 11664 13 0 13 13 0 8 0 amappl 88 6752 0 6585 5 0 5 5 0 92 0 uvmvnodes 80 3025 0 0 62 0 62 62 0 8 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 128 254 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 18 0 17 1 0 1 1 0 8 0 aobjpl 72 13 0 1 1 0 1 1 0 8 0 uaddrrnd 24 936 0 907 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 936 0 907 1 0 1 1 0 8 0 vmmpekpl 168 9212 0 9178 3 0 3 3 0 8 0 vmmpepl 168 66947 0 65141 92 0 92 92 0 357 6 vmsppl 368 935 0 907 4 0 4 4 0 8 1 rwobjpl 40 23298 0 19409 40 0 40 40 0 8 0 pdppl 4096 1879 0 1814 103 34 69 79 0 8 4 pvpl 32 428537 0 419674 112 0 112 112 0 265 26 pmappl 216 935 0 907 2 0 2 2 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 525 0 166 13 0 13 13 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(ffffffff8335dc0b) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8339b96a,ffffffff833f502d,3b9,ffffffff833ce89b) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c97f0b0,ffffffff83353fb9) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c97f0a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff800035d1efb8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80002a7b1600) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c994488,1,fffffd8007bfb820,ffff800035d1efb8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806ab69000,ffff800035d1efb8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806ab69000,ffff800035d1efb8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806ab69000,ffff800035d1efb8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806ab69000,ffff800035d1efb8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff800035d1efb8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff800035d1efb8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff800035d1efb8,ffff80002a7b1960,ffff80002a7b18b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80002a7b1960) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80002a7b1960) at syscall+0x962 sys/arch/amd64/amd64/trap.c:765 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x6fe9804f05b0, 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(ffffffff8335dc0b) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8339b96a,ffffffff833f502d,3b9,ffffffff833ce89b) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c97f0b0,ffffffff83353fb9) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:954 pppx_if_destroy(205b9a,ffff80003c97f0a8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b9a,1,2000,ffff800035d1efb8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80002a7b1600) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806c994488,1,fffffd8007bfb820,ffff800035d1efb8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806ab69000,ffff800035d1efb8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806ab69000,ffff800035d1efb8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd806ab69000,ffff800035d1efb8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806ab69000,ffff800035d1efb8) at closef+0x190 sys/kern/kern_descrip.c:1264 fdfree(ffff800035d1efb8) at fdfree+0x115 sys/kern/kern_descrip.c:1195 exit1(ffff800035d1efb8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff800035d1efb8,ffff80002a7b1960,ffff80002a7b18b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80002a7b1960) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80002a7b1960) at syscall+0x962 sys/arch/amd64/amd64/trap.c:765 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x6fe9804f05b0, count: -16