panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 955 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(ffffffff8348c159) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c5bd6,ffffffff83521b3a,3bb,ffffffff834fa355) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9131d0,ffffffff83482cc0) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff80003c9131c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff800038cd14e0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000368cf810) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffa806c5ecb28,41,fffffa8007ffd750,ffff800038cd14e0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffa806ca0d010,ffff800038cd14e0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffa806ca0d010,ffff800038cd14e0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffa806ca0d010,ffff800038cd14e0) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffa806ca0d010,ffff800038cd14e0) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff800038cd14e0) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff800038cd14e0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff800038cd14e0,ffff8000368cfb70,ffff8000368cfac0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff8000368cfb60, 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 955 ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff8348c159) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c5bd6,ffffffff83521b3a,3bb,ffffffff834fa355) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9131d0,ffffffff83482cc0) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff80003c9131c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff800038cd14e0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000368cf810) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffa806c5ecb28,41,fffffa8007ffd750,ffff800038cd14e0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffa806ca0d010,ffff800038cd14e0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffa806ca0d010,ffff800038cd14e0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffa806ca0d010,ffff800038cd14e0) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffa806ca0d010,ffff800038cd14e0) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff800038cd14e0) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff800038cd14e0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff800038cd14e0,ffff8000368cfb70,ffff8000368cfac0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff8000368cfb70) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff8000368cfb70) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7aa3a251c200, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff8000368cf5f0 rbx 0 rdx 0 rcx 0 rax 0xffff800038cd14e0 r8 0x101010101010101 r9 0x8080808080808080 r10 0x4eb75c4827ab53c r11 0xa7df62cc1803d86c r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff82c04965 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff8000368cf5e0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=50373 pid=4254 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=50, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff800038cd14e0 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff800038cd0d18,0xffff800038cd0fc0 process=0xffff8000ffff9698 user=0xffff8000368ca000, vmspace=0xfffffa806d356018 estcpu=36, cpticks=3, pctcpu=0.0, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 51775 10537 63130 0 2 0 syz-executor 51775 45343 63130 0 2 0x4000000 syz-executor 76020 401591 7823 0 2 0 syz-executor 76020 341456 7823 0 2 0x4000000 syz-executor 72171 510742 44956 0 2 0 syz-executor 72171 137604 44956 0 3 0x4000080 fsleep syz-executor 18697 463568 93389 60929 2 0x10 syz-executor 18697 344594 93389 60929 3 0x4000090 fsleep syz-executor 81960 279905 63124 0 2 0 syz-executor 81960 132559 63124 0 3 0x4000080 fsleep syz-executor 62665 106873 80114 0 2 0x2 syz-executor 63124 8333 80114 0 2 0xc82 syz-executor 42172 156821 80114 0 2 0x2 syz-executor 44956 270286 80114 0 3 0x82 nanoslp syz-executor 63130 210821 80114 0 2 0xc82 syz-executor 7823 164025 80114 0 3 0x82 nanoslp syz-executor 86836 495053 80114 0 3 0x82 nanoslp syz-executor 93389 192175 80114 0 2 0xc82 syz-executor 80114 373597 88348 0 3 0x82 kqread syz-executor 88348 227840 78840 0 3 0x10008a sigsusp ksh 78840 439650 5493 0 3 0x98 kqread sshd-session 5493 304601 67201 0 3 0x92 kqread sshd-session 14591 198288 1 0 3 0x100083 ttyin getty 67201 497627 1 0 3 0x88 kqread sshd 36011 275303 15180 73 3 0x1100090 kqread syslogd 15180 30654 1 0 3 0x100082 sbwait syslogd 74950 466202 1 0 3 0x100080 kqread resolvd 35709 159406 14423 77 2 0x100012 dhcpleased 33690 191202 14423 77 3 0x100092 kqread dhcpleased 14423 182822 1 0 3 0x80 kqread dhcpleased 52761 355075 0 0 3 0x14200 bored smr 41394 254693 0 0 2 0x14200 zerothread 47007 200487 0 0 3 0x14200 aiodoned aiodoned 77734 429519 0 0 3 0x14200 syncer update 29286 130789 0 0 3 0x14200 cleaner cleaner 59891 519582 0 0 3 0x14200 reaper reaper 26668 352835 0 0 3 0x14200 pgdaemon pagedaemon 74413 373233 0 0 3 0x14200 bored viomb 95157 257080 0 0 3 0x40014200 acpi0 acpi0 82085 288128 0 0 2 0x14200 softnet0 25396 109229 0 0 3 0x14200 smrbar systqmp 62695 473676 0 0 3 0x14200 bored systq 41830 157497 0 0 3 0x40014200 tmoslp softclock 36635 133637 0 0 3 0x40014200 idle0 1 9454 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 11030 12105K 12218K 166960K 12217 0 pcb 17 12K 12K 166960K 26 0 rtable 233 6K 7K 166960K 368 0 pf 33 13K 20K 166960K 63 0 ifaddr 42 7K 7K 166960K 51 0 ifgroup 52 2K 2K 166960K 66 0 sysctl 3 1K 9K 166960K 7 0 counters 35 18K 18K 166960K 41 0 ioctlops 0 0K 4K 166960K 49 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1305 82K 82K 166960K 1413 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 5K 166960K 3 0 VM map 2 1K 1K 166960K 2 0 sem 6 0K 0K 166960K 9 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 16 57K 240K 166960K 195 0 proc 59 59K 91K 166960K 501 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 5 0 in_multi 98 7K 7K 166960K 106 0 ether_multi 1 0K 0K 166960K 1 0 mrt 0 0K 0K 166960K 2 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 31 148K 148K 166960K 31 0 exec 0 0K 1K 166960K 372 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 202 142K 151K 166960K 3436 0 UVM aobj 5 2K 2K 166960K 5 0 pinsyscall 37 74K 94K 166960K 1292 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 NDP 29 2K 2K 166960K 32 0 temp 35 9102K 9109K 166960K 3716 0 kqueue 15 24K 26K 166960K 33 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 40 0 37 1 0 1 1 0 8 0 rtentry 136 115 0 8 4 0 4 4 0 8 0 unpcb 144 59 0 42 1 0 1 1 0 8 0 syncache 336 4 0 4 1 0 1 1 0 8 1 tcpcb 736 14 0 10 1 0 1 1 0 8 0 arp 96 18 0 2 1 0 1 1 0 8 0 inpcb 328 85 0 76 2 0 2 2 0 8 1 ip6q 72 1 0 0 1 0 1 1 0 8 0 ip6af 40 1 0 0 1 0 1 1 0 8 0 nd6 112 25 0 0 1 0 1 1 0 8 0 pkpcb 40 2 0 2 1 0 1 1 0 8 1 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1072 5 0 3 1 0 1 1 0 8 0 pppxif 1416 4 0 3 1 0 1 1 0 8 0 pfstscr 40 2 0 2 1 0 1 1 0 8 1 pfanchor 1288 8 0 1 1 0 1 1 0 8 0 pfstkey 128 2 0 2 1 0 1 1 0 8 1 pfstate 384 1 0 1 1 0 1 1 0 8 1 pfrule 1360 2 0 2 1 0 1 1 0 8 1 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 468 0 10 29 0 29 29 0 8 0 art_table 40 469 0 10 5 0 5 5 0 8 0 art_node 32 115 0 15 1 0 1 1 0 8 0 semapl 72 7 0 3 1 0 1 1 0 8 0 shmpl 112 2 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1652 0 189 92 0 92 92 0 8 0 ffsino 256 1652 0 189 92 0 92 92 0 8 0 nchpl 144 1895 0 199 64 0 64 64 0 8 0 vnodes 216 1763 0 0 98 0 98 98 0 8 0 namei 1024 5489 0 5489 2 0 2 2 0 8 2 kstatmem 264 31 0 6 2 0 2 2 0 8 0 scxspl 216 6328 0 6328 4 0 4 4 1 8 4 plimitpl 152 30 0 14 1 0 1 1 0 8 0 sigapl 424 480 0 439 6 0 6 6 0 8 1 knotepl 120 3709 0 3659 8 0 8 8 0 8 6 kqueuepl 184 34 0 21 1 0 1 1 0 8 0 pipepl 304 124 0 97 3 0 3 3 0 8 0 fdescpl 448 467 0 439 5 0 5 5 0 8 1 filepl 120 1595 0 1384 7 0 7 7 0 8 0 lockfpl 104 11 0 8 1 0 1 1 0 8 0 lockfspl 48 7 0 4 1 0 1 1 0 8 0 sessionpl 144 26 0 18 1 0 1 1 0 8 0 pgrppl 48 34 0 18 1 0 1 1 0 8 0 ucredpl 104 107 0 95 1 0 1 1 0 8 0 zombiepl 144 440 0 439 1 0 1 1 0 8 0 processpl 1152 480 0 439 4 0 4 4 0 8 0 procpl 664 536 0 490 5 0 5 5 0 8 0 sosppl 176 8 0 8 1 0 1 1 0 8 1 sockpl 552 186 0 157 3 0 3 3 0 8 0 mcl64k 65536 37 0 35 1 0 1 1 0 8 0 mcl16k 16384 17 0 17 1 0 1 1 0 8 1 mcl12k 12288 5 0 5 1 0 1 1 0 8 1 mcl9k128 9344 2 0 2 1 0 1 1 0 8 1 mcl8k 8192 14 0 13 1 0 1 1 0 8 0 mcl4k 4096 2595 0 2541 13 0 13 13 0 8 6 mcl2k2 2112 1 0 1 1 0 1 1 0 8 1 mcl2k 2048 125 0 124 1 0 1 1 0 8 0 mtagpl 96 4 0 4 1 0 1 1 0 8 1 mbufpl 256 4808 0 4663 10 0 10 10 0 8 0 bufpl 280 2288 0 102 157 0 157 157 0 8 0 anonpl 24 85134 0 82166 21 0 21 21 0 186 1 amapchunkpl 152 9195 0 8778 20 0 20 20 0 158 1 amappl16 200 1286 0 1266 4 0 4 4 0 8 2 amappl15 192 22 0 22 1 0 1 1 0 8 1 amappl14 184 409 0 408 1 0 1 1 0 8 0 amappl13 176 118 0 107 1 0 1 1 0 8 0 amappl12 168 705 0 678 2 0 2 2 0 8 0 amappl11 160 18 0 17 1 0 1 1 0 8 0 amappl10 152 59 0 49 1 0 1 1 0 8 0 amappl9 144 270 0 270 1 0 1 1 0 8 1 amappl8 136 126 0 125 1 0 1 1 0 8 0 amappl7 128 143 0 132 1 0 1 1 0 8 0 amappl6 120 147 0 146 1 0 1 1 0 8 0 amappl5 112 97 0 90 1 0 1 1 0 8 0 amappl4 104 261 0 246 1 0 1 1 0 8 0 amappl3 96 1671 0 1574 3 0 3 3 0 8 0 amappl2 88 527 0 473 2 0 2 2 0 8 0 amappl1 80 10280 0 9720 13 0 13 13 0 8 1 amappl 88 2736 0 2594 4 0 4 4 0 92 0 uvmvnodes 80 97 0 0 2 0 2 2 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 128 253 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 4 0 0 1 0 1 1 0 8 0 uaddrrnd 24 467 0 439 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 467 0 439 1 0 1 1 0 8 0 vmmpekpl 168 5676 0 5641 2 0 2 2 0 8 0 vmmpepl 168 38726 0 37019 80 0 80 80 0 357 1 vmsppl 368 466 0 439 4 0 4 4 0 8 1 rwobjpl 40 13963 0 13039 11 0 11 11 0 8 0 pdppl 4096 940 0 878 94 14 80 80 0 8 18 pvpl 32 219881 0 211730 77 0 77 77 0 265 1 pmappl 216 466 0 439 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 355 0 14 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(ffffffff8348c159) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c5bd6,ffffffff83521b3a,3bb,ffffffff834fa355) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9131d0,ffffffff83482cc0) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff80003c9131c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff800038cd14e0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000368cf810) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffa806c5ecb28,41,fffffa8007ffd750,ffff800038cd14e0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffa806ca0d010,ffff800038cd14e0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffa806ca0d010,ffff800038cd14e0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffa806ca0d010,ffff800038cd14e0) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffa806ca0d010,ffff800038cd14e0) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff800038cd14e0) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff800038cd14e0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff800038cd14e0,ffff8000368cfb70,ffff8000368cfac0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff8000368cfb70) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff8000368cfb70) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7aa3a251c200, 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(ffffffff8348c159) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834c5bd6,ffffffff83521b3a,3bb,ffffffff834fa355) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c9131d0,ffffffff83482cc0) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(0,ffff80003c9131c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,41,2000,ffff800038cd14e0) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff8000368cf810) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffa806c5ecb28,41,fffffa8007ffd750,ffff800038cd14e0) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffa806ca0d010,ffff800038cd14e0) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffa806ca0d010,ffff800038cd14e0) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffa806ca0d010,ffff800038cd14e0) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffa806ca0d010,ffff800038cd14e0) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff800038cd14e0) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff800038cd14e0,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff800038cd14e0,ffff8000368cfb70,ffff8000368cfac0) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff8000368cfb70) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff8000368cfb70) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7aa3a251c200, count: -16