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 *346439 19426 0 0 0x4000000 0 syz-executor db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83338a99) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a1de,ffffffff833d50c4,3b7,ffffffff833aed65) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff8000ffffab48,ffffffff8332fd8b) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(ffff80003814e000,ffff8000ffffab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80003a968028) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c983c30) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd80693267b0,41,fffffd8007bfb888,ffff80003a968028) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8074172f08,ffff80003a968028) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8074172f08,ffff80003a968028) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8074172f08,ffff80003a968028) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd8074172f08,ffff80003a968028) at closef+0x190 sys/kern/kern_descrip.c:1264 syscall(ffff80003c983e80) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c983e80) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xbddee456670, count: 2 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(ffffffff83338a99) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a1de,ffffffff833d50c4,3b7,ffffffff833aed65) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff8000ffffab48,ffffffff8332fd8b) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(ffff80003814e000,ffff8000ffffab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80003a968028) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c983c30) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd80693267b0,41,fffffd8007bfb888,ffff80003a968028) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8074172f08,ffff80003a968028) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8074172f08,ffff80003a968028) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8074172f08,ffff80003a968028) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd8074172f08,ffff80003a968028) at closef+0x190 sys/kern/kern_descrip.c:1264 syscall(ffff80003c983e80) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c983e80) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xbddee456670, count: -13 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80003c983a10 rbx 0 rdx 0xffff80000146a6c0 rcx 0 rax 0xffff80003a968028 r8 0x101010101010101 r9 0x8080808080808080 r10 0xd6d291f8ea990ab4 r11 0xf37d3c1a37ad1408 r12 0 r13 0 r14 0 r15 0x1 rip 0xffffffff831335a5 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80003c983a00 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb> show proc PROC (syz-executor) tid=346439 pid=19426 tcnt=2 stat=onproc flags process=0 proc=4000000 runpri=32, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0 forw=0xffffffffffffffff, list=0xffff80003a9687f0,0xffff80003a969cc0 process=0xffff80002cd2f6d8 user=0xffff80003c97e000, vmspace=0xfffffd806ba3d8b0 estcpu=36, cpticks=2, pctcpu=0.0, user=0, sys=2, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 45958 269181 59053 0 2 0 syz-executor 12502 161256 47651 0 3 0x80 nanoslp syz-executor 12502 41865 47651 0 2 0x4000000 syz-executor 12502 418963 47651 0 3 0x4000080 fsleep syz-executor 19426 227991 23385 0 2 0 syz-executor *19426 346439 23385 0 7 0x4000000 syz-executor 76232 308340 10366 0 2 0xc90 syz-executor 76232 301299 10366 0 3 0x4000090 fifow syz-executor 76232 324971 10366 0 3 0x4000090 fsleep syz-executor 90468 373714 56064 -1 2 0xc90 syz-executor 90468 188796 56064 -1 3 0x4000090 msgwait syz-executor 90468 329547 56064 -1 3 0x4000090 fsleep syz-executor 57351 81213 19102 0 3 0x80 nanoslp syz-executor 57351 22409 19102 0 3 0x4000080 kqread syz-executor 57351 423193 19102 0 3 0x4000080 fsleep syz-executor 53186 434550 15363 0 3 0x80 nanoslp syz-executor 53186 355011 15363 0 3 0x4000080 kqsel syz-executor 53186 284967 15363 0 3 0x4000080 kqsel syz-executor 53186 43804 15363 0 3 0x4000080 fsleep syz-executor 23385 466370 46600 0 2 0xc82 syz-executor 59053 473812 46600 0 2 0xc82 syz-executor 47651 209625 46600 0 2 0xc82 syz-executor 52325 96858 46600 0 2 0x2 syz-executor 10366 321481 46600 0 2 0xc82 syz-executor 19102 222219 46600 0 2 0xc82 syz-executor 15363 299624 46600 0 2 0xc82 syz-executor 56064 513262 46600 0 3 0x82 nanoslp syz-executor 46600 186340 71563 0 3 0x82 kqread syz-executor 71563 238745 15895 0 3 0x10008a sigsusp ksh 15895 329115 4148 0 3 0x98 kqread sshd-session 4148 28718 43676 0 3 0x92 kqread sshd-session 904 296169 1 0 3 0x100083 ttyin getty 43676 118867 1 0 3 0x88 kqread sshd 91278 390084 70474 73 3 0x1100090 kqread syslogd 70474 162271 1 0 3 0x100082 sbwait syslogd 29625 499419 1 0 3 0x100080 kqread resolvd 14222 183106 49522 77 2 0x100012 dhcpleased 53384 149914 49522 77 3 0x100092 kqread dhcpleased 49522 410819 1 0 3 0x80 kqread dhcpleased 49975 491013 0 0 3 0x14200 bored smr 44404 26355 0 0 2 0x14200 zerothread 61686 125596 0 0 3 0x14200 aiodoned aiodoned 61378 259651 0 0 3 0x14200 syncer update 74740 211027 0 0 3 0x14200 cleaner cleaner 27109 273117 0 0 3 0x14200 reaper reaper 55655 125877 0 0 3 0x14200 pgdaemon pagedaemon 91114 504753 0 0 3 0x14200 bored viomb 11984 508944 0 0 3 0x40014200 acpi0 acpi0 81866 242523 0 0 3 0x14200 bored softnet7 828 502929 0 0 3 0x14200 bored softnet6 19219 39789 0 0 3 0x14200 bored softnet5 28963 320986 0 0 3 0x14200 bored softnet4 65463 302029 0 0 3 0x14200 bored softnet3 31092 228377 0 0 3 0x14200 bored softnet2 28660 58857 0 0 3 0x14200 bored softnet1 83391 5654 0 0 2 0x14200 softnet0 11134 354546 0 0 3 0x14200 smrbar systqmp 88910 123247 0 0 3 0x14200 bored systq 90492 322897 0 0 3 0x40014200 tmoslp softclock 37021 382381 0 0 3 0x40014200 idle0 1 252015 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 10174 11041K 11154K 166960K 11285 0 pcb 17 12K 12K 166960K 21 0 rtable 213 6K 6K 166960K 291 0 pf 30 12K 13K 166960K 35 0 ifaddr 42 7K 8K 166960K 48 0 ifgroup 50 2K 2K 166960K 59 0 sysctl 3 1K 9K 166960K 7 0 counters 33 17K 18K 166960K 37 0 ioctlops 0 0K 2K 166960K 35 0 iov 0 0K 12K 166960K 5 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1344 85K 85K 166960K 1375 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 1K 166960K 2 0 VM map 2 1K 1K 166960K 2 0 sem 4 0K 2K 166960K 7 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 17 61K 97K 166960K 169 0 sigio 0 0K 0K 166960K 1 0 proc 60 59K 124K 166960K 478 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 6 0 in_multi 99 7K 7K 166960K 101 0 ether_multi 1 0K 0K 166960K 1 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 43 201K 201K 166960K 43 0 exec 0 0K 1K 166960K 346 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 226 159K 167K 166960K 3094 0 UVM aobj 3 2K 2K 166960K 3 0 pinsyscall 38 76K 96K 166960K 1191 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 2 0K 0K 166960K 5 0 NDP 11 0K 2K 166960K 29 0 temp 40 8631K 8706K 166960K 3818 0 kqueue 15 24K 25K 166960K 29 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 38 0 34 1 0 1 1 0 8 0 rtentry 136 103 0 9 4 0 4 4 0 8 0 unpcb 144 40 0 20 1 0 1 1 0 8 0 syncache 336 3 0 3 1 0 1 1 0 8 1 tcpcb 736 22 0 16 1 0 1 1 0 8 0 arp 88 12 0 2 1 0 1 1 0 8 0 inpcb 328 82 0 71 2 0 2 2 0 8 1 nd6 104 16 0 0 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 1384 3 0 2 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 450 0 3 28 0 28 28 0 8 0 art_table 40 451 0 3 5 0 5 5 0 8 0 art_node 32 103 0 17 1 0 1 1 0 8 0 sysvmsgpl 40 2 0 1 1 0 1 1 0 8 0 semapl 112 3 0 1 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1607 0 102 95 0 95 95 0 8 0 ffsino 256 1607 0 102 95 0 95 95 0 8 0 nchpl 144 1841 0 156 63 0 63 63 0 8 0 uvmvnodes 80 1699 0 0 35 0 35 35 0 8 0 vnodes 216 1699 0 0 95 0 95 95 0 8 0 namei 1024 5480 0 5480 2 0 2 2 0 8 2 kstatmem 264 26 0 4 2 0 2 2 0 8 0 scxspl 216 7547 0 7547 8 0 8 8 1 8 8 plimitpl 152 33 0 16 1 0 1 1 0 8 0 sigapl 424 450 0 401 7 0 7 7 0 8 1 knotepl 120 4362 0 4311 2 0 2 2 0 8 0 kqueuepl 184 36 0 19 1 0 1 1 0 8 0 pipepl 304 101 0 74 3 0 3 3 0 8 0 fdescpl 448 430 0 401 5 0 5 5 0 8 1 filepl 120 1450 0 1227 7 0 7 7 0 8 0 lockfpl 104 19 0 17 1 0 1 1 0 8 0 lockfspl 48 10 0 8 1 0 1 1 0 8 0 sessionpl 144 21 0 13 1 0 1 1 0 8 0 pgrppl 48 29 0 13 1 0 1 1 0 8 0 ucredpl 104 176 0 163 1 0 1 1 0 8 0 zombiepl 144 401 0 401 1 0 1 1 0 8 1 processpl 1168 450 0 401 5 0 5 5 0 8 1 procpl 664 519 0 458 6 0 6 6 0 8 0 sockpl 552 160 0 125 3 0 3 3 0 8 0 mcl64k 65536 4 0 4 1 0 1 1 0 8 1 mcl8k 8192 4 0 4 1 0 1 1 0 8 1 mcl4k 4096 2478 0 2425 15 0 15 15 0 8 7 mcl2k 2048 215 0 200 3 0 3 3 0 8 1 mtagpl 96 6 0 4 1 0 1 1 0 8 0 mbufpl 256 4154 0 3958 13 0 13 13 0 8 0 bufpl 280 3955 0 117 275 0 275 275 0 8 0 anonpl 24 105551 0 102476 41 0 41 41 0 187 18 amapchunkpl 152 9054 0 8576 24 0 24 24 0 158 3 amappl16 200 2109 0 2088 14 0 14 14 0 8 12 amappl15 192 7 0 7 1 0 1 1 0 8 1 amappl14 184 103 0 93 1 0 1 1 0 8 0 amappl13 176 4 0 3 1 0 1 1 0 8 0 amappl12 168 1062 0 1034 3 0 3 3 0 8 1 amappl11 160 51 0 41 1 0 1 1 0 8 0 amappl10 152 5 0 5 1 0 1 1 0 8 1 amappl9 144 256 0 256 1 0 1 1 0 8 1 amappl8 136 44 0 43 1 0 1 1 0 8 0 amappl7 128 96 0 86 1 0 1 1 0 8 0 amappl6 120 163 0 160 1 0 1 1 0 8 0 amappl5 112 112 0 106 1 0 1 1 0 8 0 amappl4 104 270 0 253 1 0 1 1 0 8 0 amappl3 96 1393 0 1286 3 0 3 3 0 8 0 amappl2 88 600 0 548 2 0 2 2 0 8 0 amappl1 80 7886 0 7342 13 0 13 13 0 8 1 amappl 88 2465 0 2303 5 0 5 5 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 2 0 0 1 0 1 1 0 8 0 uaddrrnd 24 430 0 401 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 430 0 401 1 0 1 1 0 8 0 vmmpekpl 168 4935 0 4903 2 0 2 2 0 8 0 vmmpepl 168 34235 0 32419 83 0 83 83 0 357 0 vmsppl 368 429 0 401 4 0 4 4 0 8 1 rwobjpl 40 14090 0 11553 27 0 27 27 0 8 0 pdppl 4096 866 0 802 96 30 66 82 0 8 2 pvpl 32 223778 0 215548 98 0 98 98 0 265 23 pmappl 216 429 0 401 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 372 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(ffffffff83338a99) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a1de,ffffffff833d50c4,3b7,ffffffff833aed65) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff8000ffffab48,ffffffff8332fd8b) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(ffff80003814e000,ffff8000ffffab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80003a968028) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c983c30) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd80693267b0,41,fffffd8007bfb888,ffff80003a968028) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8074172f08,ffff80003a968028) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8074172f08,ffff80003a968028) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8074172f08,ffff80003a968028) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd8074172f08,ffff80003a968028) at closef+0x190 sys/kern/kern_descrip.c:1264 syscall(ffff80003c983e80) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c983e80) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xbddee456670, count: -13 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83338a99) at panic+0x1cf sys/kern/subr_prf.c:198 __assert(ffffffff8337a1de,ffffffff833d50c4,3b7,ffffffff833aed65) at __assert+0x29 sys/kern/subr_prf.c:-1 refcnt_finalize(ffff8000ffffab48,ffffffff8332fd8b) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952 pppx_if_destroy(ffff80003814e000,ffff8000ffffab40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794 pppxclose(205b92,41,2000,ffff80003a968028) at pppxclose+0xa0 sys/net/if_pppx.c:541 spec_close(ffff80003c983c30) at spec_close+0x417 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd80693267b0,41,fffffd8007bfb888,ffff80003a968028) at VOP_CLOSE+0x129 sys/kern/vfs_vops.c:156 vn_closefile(fffffd8074172f08,ffff80003a968028) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd8074172f08,ffff80003a968028) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615 fdrop(fffffd8074172f08,ffff80003a968028) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd8074172f08,ffff80003a968028) at closef+0x190 sys/kern/kern_descrip.c:1264 syscall(ffff80003c983e80) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline] syscall(ffff80003c983e80) at syscall+0x962 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xbddee456670, count: -13