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(ffffffff8347b3a1) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834bd6b6,ffffffff8351b906,3bb,ffffffff834f4b84) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c92b1d0,ffffffff83478272) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80003c92b1c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,1,2000,ffff80003a4d1ca8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c90b770) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806537e298,1,fffffd8007ffd410,ffff80003a4d1ca8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806a5132e0,ffff80003a4d1ca8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffd806a5132e0,ffff80003a4d1ca8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffd806a5132e0,ffff80003a4d1ca8) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffd806a5132e0,ffff80003a4d1ca8) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80003a4d1ca8) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80003a4d1ca8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003a4d1ca8,ffff80003c90bad0,ffff80003c90ba20) at sys_exit+0x1a sys/kern/kern_exit.c:-1 end trace frame: 0xffff80003c90bac0, 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(ffffffff8347b3a1) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834bd6b6,ffffffff8351b906,3bb,ffffffff834f4b84) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c92b1d0,ffffffff83478272) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80003c92b1c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,1,2000,ffff80003a4d1ca8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c90b770) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806537e298,1,fffffd8007ffd410,ffff80003a4d1ca8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806a5132e0,ffff80003a4d1ca8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffd806a5132e0,ffff80003a4d1ca8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffd806a5132e0,ffff80003a4d1ca8) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffd806a5132e0,ffff80003a4d1ca8) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80003a4d1ca8) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80003a4d1ca8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003a4d1ca8,ffff80003c90bad0,ffff80003c90ba20) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c90bad0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c90bad0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ee97c07deb0, count: -16 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003c90b550 rbx 0 rdx 0 rcx 0 rax 0xffff80003a4d1ca8 r8 0x101010101010101 r9 0x8080808080808080 r10 0x92697f987fd0a7c r11 0xc21c41e72460f6d0 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff82b64e75 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c90b540 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=377147 pid=33149 tcnt=0 stat=onproc flags process=1008 proc=2000 runpri=32, usrpri=79, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0xffff80003a4d1ca8 scnt=-1 ecnt=1 forw=0xffffffffffffffff, list=0xffff80003a4d0fb0,0xffff80002a737770 process=0xffff8000ffff8498 user=0xffff80003c906000, vmspace=0xfffffd806cac35d0 estcpu=29, cpticks=5, pctcpu=0.3, user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 5978 459453 858 0 2 0 syz-executor 5978 28456 858 0 3 0x4000080 fsleep syz-executor 37941 20264 43125 0 2 0 syz-executor 37941 94797 43125 0 3 0x4000000 smrbar syz-executor 57485 376487 35124 0 2 0 syz-executor 57485 207906 35124 0 2 0x4000000 syz-executor 48800 514799 18431 0 2 0xc80 syz-executor 48800 326825 18431 0 3 0x4000080 msgwait syz-executor 48800 417640 18431 0 3 0x4000080 fsleep syz-executor 6738 339552 1 0 3 0x80 nanoslp init 45097 45394 85208 0 2 0xc82 syz-executor 34314 332684 85208 0 3 0x82 nanoslp syz-executor 18431 339785 85208 0 2 0xc82 syz-executor 858 32974 85208 0 2 0xc82 syz-executor 35124 375881 85208 0 2 0xc82 syz-executor 7431 284277 85208 0 2 0x2 syz-executor 19418 277169 85208 0 2 0xc82 syz-executor 43125 28953 85208 0 2 0xc82 syz-executor 85208 473374 52722 0 3 0x82 kqread syz-executor 52722 499178 81848 0 3 0x10008a sigsusp ksh 81848 158380 54414 0 3 0x98 kqread sshd-session 54414 507080 80583 0 3 0x92 kqread sshd-session 80583 354120 1 0 3 0x88 kqread sshd 2747 178528 45378 73 3 0x1100090 kqread syslogd 45378 514317 1 0 3 0x100082 sbwait syslogd 56502 268567 1 0 3 0x100080 kqread resolvd 22874 3081 16326 77 3 0x100092 kqread dhcpleased 6482 72321 16326 77 3 0x100092 kqread dhcpleased 16326 118526 1 0 3 0x80 kqread dhcpleased 35182 369563 0 0 3 0x14200 bored smr 89950 435975 0 0 2 0x14200 zerothread 43260 354274 0 0 3 0x14200 aiodoned aiodoned 44305 101508 0 0 3 0x14200 syncer update 49883 102977 0 0 3 0x14200 cleaner cleaner 56812 448520 0 0 3 0x14200 reaper reaper 43052 152904 0 0 3 0x14200 pgdaemon pagedaemon 14091 299776 0 0 3 0x14200 bored viomb 16267 292825 0 0 3 0x40014200 acpi0 acpi0 19794 333800 0 0 3 0x14200 bored softnet0 13000 245458 0 0 3 0x14200 smrbar systqmp 85483 44883 0 0 3 0x14200 bored systq 91118 26062 0 0 3 0x40014200 tmoslp softclock 87351 438005 0 0 3 0x40014200 idle0 1 475676 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 11038 12162K 12362K 166960K 12248 0 pcb 17 12K 12K 166960K 54 0 rtable 224 8K 9K 166960K 407 0 pf 30 13K 20K 166960K 51 0 ifaddr 36 6K 7K 166960K 48 0 ifgroup 47 2K 2K 166960K 60 0 sysctl 3 1K 9K 166960K 8 0 counters 33 17K 17K 166960K 38 0 ioctlops 0 0K 4K 166960K 69 0 iov 0 0K 4K 166960K 69 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1297 82K 82K 166960K 1483 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 12 0K 1K 166960K 80 0 dirhash 12 2K 2K 166960K 15 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 17 61K 97K 166960K 288 0 proc 51 50K 124K 166960K 518 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 31 0 in_multi 78 5K 7K 166960K 103 0 ether_multi 1 0K 0K 166960K 2 0 mrt 0 0K 0K 166960K 3 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 73 334K 334K 166960K 73 0 exec 0 0K 1K 166960K 547 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 207 146K 173K 166960K 4235 0 UVM aobj 6 2K 2K 166960K 7 0 pinsyscall 37 74K 96K 166960K 1413 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 6 0 NDP 10 0K 2K 166960K 29 0 temp 39 9103K 9171K 166960K 13423 0 kqueue 14 22K 26K 166960K 60 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 53 0 50 1 0 1 1 0 8 0 rtentry 136 121 0 25 4 0 4 4 0 8 0 unpcb 144 315 0 299 9 0 9 9 0 8 8 syncache 336 7 0 7 1 0 1 1 0 8 1 tcpcb 736 44 0 40 1 0 1 1 0 8 0 arp 96 19 0 4 1 0 1 1 0 8 0 inpcb 328 167 0 157 2 0 2 2 0 8 0 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 28 0 6 1 0 1 1 0 8 0 kcovpl 48 8 0 0 1 0 1 1 0 8 0 ppxss 1072 3 0 2 1 0 1 1 0 8 0 pppxif 1416 3 0 2 1 0 1 1 0 8 0 pfstscr 40 2 0 2 1 0 1 1 0 8 1 pfanchor 1288 2 0 0 1 0 1 1 0 8 0 pftag 88 1 0 0 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 3 0 3 1 0 1 1 0 8 1 art_heap8 4096 3 0 0 3 0 3 3 0 8 0 art_heap4 256 489 0 50 29 0 29 29 0 8 1 art_table 40 492 0 50 5 0 5 5 0 8 0 art_node 32 120 0 22 1 0 1 1 0 8 0 sysvmsgpl 40 2 0 1 1 0 1 1 0 8 0 semupl 112 2 0 2 1 0 1 1 0 8 1 semapl 64 78 0 68 1 0 1 1 0 8 0 shmpl 112 4 0 1 1 0 1 1 0 8 0 dirhash 1024 19 0 2 3 0 3 3 0 8 0 dino2pl 256 1839 0 381 92 0 92 92 0 8 0 ffsino 256 1840 0 381 92 0 92 92 0 8 0 nchpl 144 2234 0 531 64 0 64 64 0 8 0 vnodes 216 1997 0 0 111 0 111 111 0 8 0 namei 1024 7014 0 7012 2 0 2 2 0 8 1 kstatmem 264 27 0 6 2 0 2 2 0 8 0 scsiplug 72 3 0 3 1 0 1 1 0 8 1 scxspl 216 7872 0 7872 8 0 8 8 1 8 8 plimitpl 152 47 0 32 1 0 1 1 0 8 0 sigapl 424 589 0 547 6 0 6 6 0 8 0 knotepl 120 8561 0 8513 10 0 10 10 0 8 7 kqueuepl 184 74 0 63 1 0 1 1 0 8 0 pipepl 304 196 0 169 8 0 8 8 0 8 5 fdescpl 448 576 0 547 5 0 5 5 0 8 1 filepl 120 2564 0 2350 13 0 13 13 0 8 6 lockfpl 104 79 0 77 1 0 1 1 0 8 0 lockfspl 48 30 0 28 1 0 1 1 0 8 0 sessionpl 144 30 0 23 1 0 1 1 0 8 0 pgrppl 48 48 0 33 1 0 1 1 0 8 0 ucredpl 104 222 0 211 1 0 1 1 0 8 0 zombiepl 144 550 0 547 1 0 1 1 0 8 0 processpl 1152 589 0 547 4 0 4 4 0 8 0 procpl 664 811 0 764 5 0 5 5 0 8 0 sockpl 552 541 0 512 17 0 17 17 0 8 14 mcl64k 65536 8 0 8 1 0 1 1 0 8 1 mcl12k 12288 1 0 1 1 0 1 1 0 8 1 mcl8k 8192 6 0 6 1 0 1 1 0 8 1 mcl4k 4096 2741 0 2689 16 1 15 16 0 8 7 mcl2k 2048 258 0 256 1 0 1 1 0 8 0 mtagpl 96 6 0 6 1 0 1 1 0 8 1 mbufpl 256 5782 0 5644 11 0 11 11 0 8 1 bufpl 280 2660 0 102 183 0 183 183 0 8 0 anonpl 24 109334 0 106210 32 0 32 32 0 186 11 amapchunkpl 152 13307 0 12862 33 0 33 33 0 158 13 amappl16 200 1849 0 1824 5 0 5 5 0 8 3 amappl15 192 98 0 98 1 0 1 1 0 8 1 amappl14 184 411 0 410 1 0 1 1 0 8 0 amappl13 176 121 0 112 1 0 1 1 0 8 0 amappl12 168 817 0 790 2 0 2 2 0 8 0 amappl11 160 5 0 5 1 0 1 1 0 8 1 amappl10 152 63 0 53 1 0 1 1 0 8 0 amappl9 144 303 0 303 1 0 1 1 0 8 1 amappl8 136 94 0 93 1 0 1 1 0 8 0 amappl7 128 149 0 137 1 0 1 1 0 8 0 amappl6 120 148 0 146 1 0 1 1 0 8 0 amappl5 112 112 0 105 1 0 1 1 0 8 0 amappl4 104 274 0 258 1 0 1 1 0 8 0 amappl3 96 2372 0 2271 3 0 3 3 0 8 0 amappl2 88 553 0 498 2 0 2 2 0 8 0 amappl1 80 11728 0 11201 15 0 15 15 0 8 2 amappl 88 3489 0 3339 4 0 4 4 0 92 0 uvmvnodes 80 101 0 0 3 0 3 3 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 7 0 7 1 0 1 1 0 8 1 dma128 128 255 0 255 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 6 0 1 1 0 1 1 0 8 0 uaddrrnd 24 576 0 547 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 576 0 547 1 0 1 1 0 8 0 vmmpekpl 168 7119 0 7084 2 0 2 2 0 8 0 vmmpepl 168 46753 0 45025 92 0 92 92 0 357 10 vmsppl 368 575 0 547 4 0 4 4 0 8 1 rwobjpl 40 16578 0 15678 12 0 12 12 0 8 1 pdppl 4096 1158 0 1094 100 34 66 82 0 8 2 pvpl 32 277399 0 268185 106 0 106 106 0 265 24 pmappl 216 575 0 547 3 0 3 3 0 8 1 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 366 0 35 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(ffffffff8347b3a1) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834bd6b6,ffffffff8351b906,3bb,ffffffff834f4b84) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c92b1d0,ffffffff83478272) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80003c92b1c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,1,2000,ffff80003a4d1ca8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c90b770) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806537e298,1,fffffd8007ffd410,ffff80003a4d1ca8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806a5132e0,ffff80003a4d1ca8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffd806a5132e0,ffff80003a4d1ca8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffd806a5132e0,ffff80003a4d1ca8) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffd806a5132e0,ffff80003a4d1ca8) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80003a4d1ca8) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80003a4d1ca8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003a4d1ca8,ffff80003c90bad0,ffff80003c90ba20) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c90bad0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c90bad0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ee97c07deb0, 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(ffffffff8347b3a1) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff834bd6b6,ffffffff8351b906,3bb,ffffffff834f4b84) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff80003c92b1d0,ffffffff83478272) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:956 pppx_if_destroy(285b9a,ffff80003c92b1c8) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(285b9a,1,2000,ffff80003a4d1ca8) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c90b770) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd806537e298,1,fffffd8007ffd410,ffff80003a4d1ca8) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806a5132e0,ffff80003a4d1ca8) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:298 [inline] vn_closefile(fffffd806a5132e0,ffff80003a4d1ca8) at vn_closefile+0x11d sys/kern/vfs_vnops.c:621 fdrop(fffffd806a5132e0,ffff80003a4d1ca8) at fdrop+0x121 sys/kern/kern_descrip.c:1281 closef(fffffd806a5132e0,ffff80003a4d1ca8) at closef+0x190 sys/kern/kern_descrip.c:1265 fdfree(ffff80003a4d1ca8) at fdfree+0x115 sys/kern/kern_descrip.c:1196 exit1(ffff80003a4d1ca8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff80003a4d1ca8,ffff80003c90bad0,ffff80003c90ba20) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c90bad0) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c90bad0) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7ee97c07deb0, count: -16