panic: kernel diagnostic assertion "kd_lookup(kd->kd_unit) == NULL" failed: file "/syzkaller/managers/multicore/kernel/sys/dev/kcov.c", line 306 Stopped at db_enter+0x25: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND * 3612 84429 0 0 0x4000000 0K syz-executor db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83466a0b) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff83413bf2,ffffffff8335262f,132,ffffffff833f1155) at __assert+0x29 sys/kern/subr_prf.c:-1 kcovopen(113d4,1,2000,ffff8000fffe27e0) at kcovopen+0x14f kd_lookup sys/dev/kcov.c:478 [inline] kcovopen(113d4,1,2000,ffff8000fffe27e0) at kcovopen+0x14f sys/dev/kcov.c:306 spec_open_clone(ffff80002a30feb8) at spec_open_clone+0x287 sys/kern/spec_vnops.c:722 spec_open(ffff80002a30feb8) at spec_open+0x329 sys/kern/spec_vnops.c:148 VOP_OPEN(fffffd8072b13018,1,fffffd80097fb7b8,ffff8000fffe27e0) at VOP_OPEN+0x8b sys/kern/vfs_vops.c:138 vn_open(ffff80002a310108,1,0) at vn_open+0x708 sys/kern/vfs_vnops.c:177 doopenat(ffff8000fffe27e0,ffffff9c,200000000080,0,0,ffff80002a3102b0) at doopenat+0x32e sys/kern/vfs_syscalls.c:1137 syscall(ffff80002a310360) at syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80002a310360) at syscall+0xbc6 sys/arch/amd64/amd64/trap.c:579 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x8b923d4abb0, count: 4 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{0}> ddb{0}> set $lines = 0 ddb{0}> set $maxwidth = 0 ddb{0}> show panic *cpu0: kernel diagnostic assertion "kd_lookup(kd->kd_unit) == NULL" failed: file "/syzkaller/managers/multicore/kernel/sys/dev/kcov.c", line 306 ddb{0}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83466a0b) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff83413bf2,ffffffff8335262f,132,ffffffff833f1155) at __assert+0x29 sys/kern/subr_prf.c:-1 kcovopen(113d4,1,2000,ffff8000fffe27e0) at kcovopen+0x14f kd_lookup sys/dev/kcov.c:478 [inline] kcovopen(113d4,1,2000,ffff8000fffe27e0) at kcovopen+0x14f sys/dev/kcov.c:306 spec_open_clone(ffff80002a30feb8) at spec_open_clone+0x287 sys/kern/spec_vnops.c:722 spec_open(ffff80002a30feb8) at spec_open+0x329 sys/kern/spec_vnops.c:148 VOP_OPEN(fffffd8072b13018,1,fffffd80097fb7b8,ffff8000fffe27e0) at VOP_OPEN+0x8b sys/kern/vfs_vops.c:138 vn_open(ffff80002a310108,1,0) at vn_open+0x708 sys/kern/vfs_vnops.c:177 doopenat(ffff8000fffe27e0,ffffff9c,200000000080,0,0,ffff80002a3102b0) at doopenat+0x32e sys/kern/vfs_syscalls.c:1137 syscall(ffff80002a310360) at syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80002a310360) at syscall+0xbc6 sys/arch/amd64/amd64/trap.c:579 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x8b923d4abb0, count: -11 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff80002a30fc90 rbx 0xffffffff8382bdd7 cpu_info_full_primary+0x2dd7 rdx 0xffff800001475680 rcx 0xffff8000fffe27e0 rax 0xffffffff8382aff0 cpu_info_full_primary+0x1ff0 r8 0x101010101010101 r9 0x8080808080808080 r10 0xafe31ff5f0e9f739 r11 0x6fc8c68a7a1670c0 r12 0xffffffff8382bbd8 cpu_info_full_primary+0x2bd8 r13 0 r14 0 r15 0x1 rip 0xffffffff81757c05 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80002a30fc80 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor) tid=3612 pid=84429 tcnt=5 stat=onproc flags process=0 proc=4000000 runpri=86, usrpri=86, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0 forw=0xffffffffffffffff, list=0xffff8000fffeacf8,0xffffffff83922c10 process=0xffff8000ffff7a28 user=0xffff80002a30b000, vmspace=0xfffffd800b026960 estcpu=36, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 84429 332891 64609 0 2 0 syz-executor 84429 163317 64609 0 3 0x4000080 ttyopn syz-executor 84429 427533 64609 0 3 0x4000080 ttyopn syz-executor 84429 96679 64609 0 3 0x4000080 ttyopn syz-executor *84429 3612 64609 0 7 0x4000000 syz-executor 91792 426681 53632 0 2 0 syz-executor 91792 446415 53632 0 3 0x4000080 ttyopn syz-executor 91792 268276 53632 0 3 0x4000080 ttyopn syz-executor 91792 499330 53632 0 3 0x4000080 ttyopn syz-executor 91792 92196 53632 0 3 0x4000080 fsleep syz-executor 77652 205204 0 0 3 0x14200 acct acct 88056 22428 1 0 3 0x100083 ttyin getty 6283 450098 9990 0 3 0x82 nanoslp syz-executor 64650 296722 9990 0 3 0x2 biowait syz-executor 53632 456597 9990 0 3 0x82 nanoslp syz-executor 16870 153722 0 0 3 0x14200 bored sosplice 94177 519795 9990 0 2 0x2 syz-executor 8756 180926 9990 0 3 0x82 piperd syz-executor 48752 161888 9990 0 2 0x2 syz-executor 33161 69013 9990 0 3 0x82 piperd syz-executor 64609 485753 9990 0 3 0x82 nanoslp syz-executor 9990 54474 43259 0 3 0x82 nanoslp syz-executor 43259 191156 1370 0 3 0x10008a sigsusp ksh 1370 462176 71331 0 3 0x98 kqread sshd-session 71331 340936 82491 0 3 0x92 kqread sshd-session 82491 177423 1 0 3 0x88 kqread sshd 10997 446802 98702 74 3 0x1100092 bpf pflogd 98702 465576 1 0 3 0x80 sbwait pflogd 69598 283984 25617 73 3 0x1100090 kqread syslogd 25617 12662 1 0 3 0x100082 sbwait syslogd 152 518239 1 0 3 0x100080 kqread resolvd 80583 448814 47616 77 3 0x100092 kqread dhcpleased 11761 475301 47616 77 3 0x100092 kqread dhcpleased 47616 417806 1 0 3 0x80 kqread dhcpleased 46472 348623 0 0 3 0x14200 bored smr 77407 485880 0 0 2 0x14200 zerothread 23276 240256 0 0 3 0x14200 aiodoned aiodoned 13810 15233 0 0 3 0x14200 syncer update 31543 466343 0 0 3 0x14200 cleaner cleaner 46684 82877 0 0 3 0x14200 reaper reaper 6767 48446 0 0 3 0x14200 pgdaemon pagedaemon 14951 163138 0 0 3 0x14200 bored viomb 70166 64943 0 0 3 0x40014200 acpi0 acpi0 57459 376898 0 0 7 0x40014200 idle1 69726 273515 0 0 3 0x14200 bored softnet3 85785 485618 0 0 3 0x14200 bored softnet2 99276 416404 0 0 3 0x14200 bored softnet1 86339 359752 0 0 3 0x14200 bored softnet0 62176 93521 0 0 3 0x14200 bored systqmp 5544 396013 0 0 3 0x14200 bored systq 94622 196286 0 0 3 0x14200 tmoslp softclockmp 31073 471880 0 0 3 0x40014200 tmoslp softclock 50979 23921 0 0 3 0x40014200 idle0 1 356796 0 0 3 0x82 wait init 0 0 -1 0 3 0x10010200 scheduler swapper ddb{0}> show all locks CPU 0: exclusive mutex /syzkaller/managers/multicore/kernel/sys/dev/kcov.c:129 r = 0 (0xffffffff8383af00) #0 witness_lock+0x5bb stacktrace_save sys/sys/stacktrace.h:37 [inline] #0 witness_lock+0x5bb sys/kern/subr_witness.c:1160 #1 mtx_enter_try+0x1ad sys/kern/kern_lock.c:298 #2 mtx_enter+0x62 sys/kern/kern_lock.c:255 #3 kcovopen+0x63 sys/dev/kcov.c:306 #4 spec_open_clone+0x287 sys/kern/spec_vnops.c:722 #5 spec_open+0x329 sys/kern/spec_vnops.c:148 #6 VOP_OPEN+0x8b sys/kern/vfs_vops.c:138 #7 vn_open+0x708 sys/kern/vfs_vnops.c:177 #8 doopenat+0x32e sys/kern/vfs_syscalls.c:1137 #9 syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] #9 syscall+0xbc6 sys/arch/amd64/amd64/trap.c:579 #10 Xsyscall+0x128 Process 84429 (syz-executor) thread 0xffff8000fffe27e0 (3612) Process 64650 (syz-executor) thread 0xffff8000fffe2f90 (296722) Process 94177 (syz-executor) thread 0xffff8000ffff07d0 (519795) Process 48752 (syz-executor) thread 0xffff8000ffff02b0 (161888) ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10204 11042K 11475K 166960K 14317 0 pcb 19 12K 12K 166960K 316 0 rtable 84 10K 12K 166960K 752 0 pf 28 16K 82K 166960K 263 0 ifaddr 15 2K 7K 166960K 169 0 ifgroup 35 1K 2K 166960K 296 0 sysctl 4 1K 9K 166960K 14 0 counters 58 35K 37K 166960K 350 0 ioctlops 0 0K 4K 166960K 1756 0 iov 0 0K 24K 166960K 68 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1348 85K 85K 166960K 3151 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 48K 60K 166960K 25 0 VM map 2 1K 1K 166960K 2 0 sem 18 37K 37K 166960K 36 0 dirhash 18 3K 3K 166960K 81 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 15 53K 98K 166960K 3312 0 sigio 0 0K 0K 166960K 35 0 proc 73 91K 140K 166960K 780 0 subproc 74 4K 4K 166960K 113 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 187 0 in_multi 13 1K 7K 166960K 234 0 ether_multi 1 0K 0K 166960K 20 0 mrt 2 0K 0K 166960K 56 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 97 440K 440K 166960K 97 0 exec 0 0K 1K 166960K 541 0 fusefs mount 1 32K 32K 166960K 1 0 pfkey data 0 0K 0K 166960K 1 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 223 160K 168K 166960K 28781 0 UVM aobj 36 2K 4K 166960K 40 0 pinsyscall 40 80K 100K 166960K 4527 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 109 0 NDP 7 0K 2K 166960K 114 0 temp 57 8690K 8799K 166960K 88238 0 kqueue 13 20K 30K 166960K 274 0 SYN cache 2 16K 16K 166960K 2 0 ddb{0}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle plcache 128 26 0 0 1 0 1 1 0 8 0 rtpcb 120 100 0 97 1 0 1 1 0 8 0 rtentry 176 246 0 229 6 2 4 6 0 8 0 unpcb 144 589 0 572 2 1 1 2 0 8 0 syncache 336 5 0 5 2 2 0 1 0 8 0 tcpcb 736 396 0 391 1 0 1 1 0 8 0 arp 128 40 0 36 1 0 1 1 0 8 0 inpcb 328 1396 0 1386 5 3 2 2 0 8 0 nd6 144 40 0 38 1 0 1 1 0 8 0 pkpcb 40 7 0 7 3 3 0 1 0 8 0 kcovpl 48 12 0 4 1 0 1 1 0 8 0 mppekey 1024 1 0 1 1 1 0 1 0 8 0 ppxss 1192 108 0 108 3 2 1 1 0 8 1 pppxif 1504 19 0 19 3 3 0 1 0 8 0 pffrag 232 11 0 10 2 1 1 1 0 482 0 pffrnode 88 9 0 8 2 1 1 1 0 8 0 pffrent 40 17 0 15 2 1 1 1 0 8 0 pfosfp 40 1430 0 1006 5 0 5 5 0 8 0 pfosfpen 112 1430 0 714 21 0 21 21 0 8 0 pfrktable 1344 2 0 0 1 0 1 1 0 8 0 pfanchor 1288 1 0 1 1 1 0 1 0 8 0 pftag 88 3 0 0 1 0 1 1 0 8 0 pfstitem 24 162 0 129 1 0 1 1 0 8 0 pfstkey 128 162 0 129 4 0 4 4 0 8 0 pfstate 384 162 0 129 11 1 10 11 0 8 0 pfrule 1344 51 0 35 3 1 2 2 0 8 0 rttmr 136 16 0 16 3 3 0 1 0 8 0 art_heap8 4096 3 0 1 3 1 2 3 0 8 0 art_heap4 256 1138 0 1042 30 19 11 29 0 8 1 art_table 32 1141 0 1043 4 2 2 4 0 8 0 art_node 16 239 0 228 1 0 1 1 0 8 0 sysvmsgpl 40 12 0 8 1 0 1 1 0 8 0 semupl 112 2 0 2 2 2 0 1 0 8 0 semapl 112 28 0 12 1 0 1 1 0 8 0 shmpl 112 37 0 4 1 0 1 1 0 8 0 dirhash 1024 64 0 43 3 0 3 3 0 8 0 dino2pl 256 6228 0 4714 96 0 96 96 0 8 0 ffsino 288 6228 0 4714 109 0 109 109 0 8 0 nchpl 144 9862 0 9300 63 38 25 63 0 8 0 rtmask 32 27 0 27 4 3 1 1 0 8 1 uvmvnodes 80 3125 0 0 64 0 64 64 0 8 0 vnodes 216 3125 0 0 174 0 174 174 0 8 0 namei 1024 25629 0 25629 2 1 1 1 0 8 1 percpumem 16 190 0 146 1 0 1 1 0 8 0 kstatmem 264 182 0 164 3 1 2 3 0 8 0 acpiwqpl 32 1 0 1 1 0 1 1 1 8 1 scsiplug 72 12 0 12 8 8 0 1 0 8 0 scxspl 216 32165 0 32164 12 11 1 8 1 8 0 plimitpl 152 183 0 166 1 0 1 1 0 8 0 sigapl 424 3614 0 3565 8 2 6 7 0 8 0 knotepl 120 562 0 0 16 0 16 16 0 8 0 kqueuepl 224 414 0 405 2 1 1 2 0 8 0 pipepl 336 188 0 161 4 1 3 3 0 8 0 fdescpl 520 3588 0 3559 3 0 3 3 0 8 0 filepl 160 10228 0 10010 10 0 10 10 0 8 0 lockfpl 104 523 0 521 1 0 1 1 0 8 0 lockfspl 48 226 0 224 1 0 1 1 0 8 0 sessionpl 144 31 0 22 1 0 1 1 0 8 0 pgrppl 48 57 0 40 1 0 1 1 0 8 0 ucredpl 104 1304 0 1290 1 0 1 1 0 8 0 zombiepl 144 4462 0 4461 3 2 1 1 0 8 0 processpl 1240 3614 0 3565 6 1 5 5 0 8 0 procpl 656 7651 0 7594 7 1 6 6 0 8 0 srpgc 96 29 0 29 7 7 0 1 0 8 0 sosppl 168 40 0 40 4 4 0 1 0 8 0 sockpl 728 2110 0 2079 7 3 4 5 0 8 0 mcl64k 65536 5 0 0 1 0 1 1 0 8 0 mcl16k 16384 3 0 0 1 0 1 1 0 8 0 mcl12k 12288 5 0 0 1 0 1 1 0 8 0 mcl9k 9216 6 0 0 1 0 1 1 0 8 0 mcl8k 8192 13 0 0 2 0 2 2 0 8 0 mcl4k 4096 109 0 0 14 0 14 14 0 8 0 mcl2k2 2112 2 0 0 1 0 1 1 0 8 0 mcl2k 2048 15 0 0 2 0 2 2 0 8 0 mtagpl 96 53 0 0 2 0 2 2 0 8 0 mbufpl 256 1191 0 0 74 0 74 74 0 8 0 bufpl 280 9381 0 3239 439 0 439 439 0 8 0 anonpl 32 10641 0 0 86 0 86 86 0 246 0 amapchunkpl 152 97237 0 96793 51 28 23 30 0 158 0 amappl16 200 6564 0 6528 54 51 3 25 0 8 0 amappl15 192 11 0 11 2 2 0 1 0 8 0 amappl14 184 128 0 116 1 0 1 1 0 8 0 amappl13 176 6 0 6 1 1 0 1 0 8 0 amappl12 168 4309 0 4282 3 1 2 2 0 8 0 amappl11 160 52 0 38 1 0 1 1 0 8 0 amappl10 152 17 0 15 2 1 1 1 0 8 0 amappl9 144 314 0 314 2 2 0 1 0 8 0 amappl8 136 58 0 55 1 0 1 1 0 8 0 amappl7 128 121 0 109 1 0 1 1 0 8 0 amappl6 120 216 0 213 2 1 1 1 0 8 0 amappl5 112 150 0 140 1 0 1 1 0 8 0 amappl4 104 339 0 319 1 0 1 1 0 8 0 amappl3 96 21676 0 21583 5 1 4 4 0 8 0 amappl2 88 708 0 645 2 0 2 2 0 8 0 amappl1 80 22177 0 21591 16 2 14 14 0 8 0 amappl 88 27772 0 27622 6 1 5 5 0 92 0 dma65536 65536 1 0 1 1 1 0 1 0 8 0 dma16384 16384 1 0 1 1 1 0 1 0 8 0 dma4096 4096 2 0 2 2 2 0 1 0 8 0 dma1024 1024 2 0 1 1 0 1 1 0 8 0 dma512 512 1 0 1 1 1 0 1 0 8 0 dma256 256 7 0 7 2 2 0 1 0 8 0 dma128 128 259 0 259 6 6 0 1 0 8 0 dma64 64 8 0 8 3 3 0 1 0 8 0 dma32 32 7 0 7 1 1 0 1 0 8 0 dma16 16 19 0 18 1 0 1 1 0 8 0 aobjpl 72 39 0 4 1 0 1 1 0 8 0 uaddrrnd 24 3588 0 3559 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 3588 0 3559 1 0 1 1 0 8 0 vmmpekpl 168 24800 0 24744 3 0 3 3 0 8 0 vmmpepl 168 214039 0 212206 123 32 91 106 0 357 0 vmsppl 480 3587 0 3559 7 3 4 5 0 8 0 rwobjpl 72 50663 0 46576 85 9 76 79 0 8 0 pdppl 4096 7183 0 7118 115 44 71 85 0 8 6 pvpl 32 18731 0 0 153 2 151 151 0 265 0 pmappl 256 3587 0 3559 4 1 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 472 0 77 12 0 12 12 0 8 0 ddb{0}> machine ddbcpu 0 Invalid cpu 0 ddb{0}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83466a0b) at panic+0x1e5 sys/kern/subr_prf.c:198 __assert(ffffffff83413bf2,ffffffff8335262f,132,ffffffff833f1155) at __assert+0x29 sys/kern/subr_prf.c:-1 kcovopen(113d4,1,2000,ffff8000fffe27e0) at kcovopen+0x14f kd_lookup sys/dev/kcov.c:478 [inline] kcovopen(113d4,1,2000,ffff8000fffe27e0) at kcovopen+0x14f sys/dev/kcov.c:306 spec_open_clone(ffff80002a30feb8) at spec_open_clone+0x287 sys/kern/spec_vnops.c:722 spec_open(ffff80002a30feb8) at spec_open+0x329 sys/kern/spec_vnops.c:148 VOP_OPEN(fffffd8072b13018,1,fffffd80097fb7b8,ffff8000fffe27e0) at VOP_OPEN+0x8b sys/kern/vfs_vops.c:138 vn_open(ffff80002a310108,1,0) at vn_open+0x708 sys/kern/vfs_vnops.c:177 doopenat(ffff8000fffe27e0,ffffff9c,200000000080,0,0,ffff80002a3102b0) at doopenat+0x32e sys/kern/vfs_syscalls.c:1137 syscall(ffff80002a310360) at syscall+0xbc6 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80002a310360) at syscall+0xbc6 sys/arch/amd64/amd64/trap.c:579 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x8b923d4abb0, count: -11 ddb{0}> machine ddbcpu 1