panic: Data modified on freelist: word 4 of object 0xffff800000bf6800 size 0x194 previous type counters (0x6563 != 0xdead4110) Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *134399 4265 0 0 0x4000000 0 syz-executor.6 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff8256db42) at panic+0x161 sys/kern/subr_prf.c:202 malloc(194,e,1) at malloc+0xa85 sys/kern/kern_malloc.c:363 sys_ioctl(ffff8000ffff8548,ffff80002e9910d8,ffff80002e991130) at sys_ioctl+0x2b1 syscall(ffff80002e9911a0) at syscall+0x447 sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xdd52b848f20, count: 9 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: Data modified on freelist: word 4 of object 0xffff800000bf6800 size 0x194 previous type counters (0x6563 != 0xdead4110) ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff8256db42) at panic+0x161 sys/kern/subr_prf.c:202 malloc(194,e,1) at malloc+0xa85 sys/kern/kern_malloc.c:363 sys_ioctl(ffff8000ffff8548,ffff80002e9910d8,ffff80002e991130) at sys_ioctl+0x2b1 syscall(ffff80002e9911a0) at syscall+0x447 sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xdd52b848f20, count: -6 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80002e990e20 rbx 0xffff800000bf6800 rdx 0xffff800000bcd500 rcx 0 rax 0xffff8000ffff8548 r8 0x101010101010101 r9 0x8080808080808080 r10 0xca13041f91b47e33 r11 0x8660feca50605ed0 r12 0 r13 0x51 r14 0 r15 0x1 rip 0xffffffff815e76a8 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff80002e990e10 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (syz-executor.6) pid=134399 stat=onproc flags process=0 proc=4000000 pri=32, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff8000216f17a0,0xffff800021781a50 process=0xffff80002170cfb8 user=0xffff80002e98c000, vmspace=0xfffffd805c27f558 estcpu=36, cpticks=1, pctcpu=0.0 user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 39985 310657 44291 0 3 0x80 nanoslp syz-executor.3 39985 201049 44291 0 3 0x4000080 fsleep syz-executor.3 63717 89784 3139 0 2 0 syz-executor.1 63717 100395 3139 0 3 0x4000080 fsleep syz-executor.1 98950 396657 39622 0 2 0 syz-executor.4 98950 43589 39622 0 3 0x4000080 fsleep syz-executor.4 37591 375413 56579 0 2 0 syz-executor.0 37591 392515 56579 0 3 0x4000080 fsleep syz-executor.0 4265 394253 68611 0 2 0 syz-executor.6 * 4265 134399 68611 0 7 0x4000000 syz-executor.6 44291 311843 25657 0 3 0x82 nanoslp syz-executor.3 16140 338520 25657 0 3 0x82 nanoslp syz-executor.2 70753 187865 25657 0 3 0x2 biowait syz-executor.5 39622 355957 25657 0 3 0x82 nanoslp syz-executor.4 23821 238475 1 0 3 0x100083 ttyin getty 3139 77155 25657 0 3 0x82 nanoslp syz-executor.1 32286 447463 0 0 3 0x14280 nfsidl nfsio 99402 315557 0 0 3 0x14280 nfsidl nfsio 65671 352063 0 0 3 0x14280 nfsidl nfsio 73594 265852 0 0 3 0x14280 nfsidl nfsio 13081 274500 0 0 3 0x14280 nfsidl nfsio 76793 40912 0 0 3 0x14280 nfsidl nfsio 48924 331589 0 0 3 0x14280 nfsidl nfsio 71408 167149 0 0 3 0x14280 nfsidl nfsio 46928 388178 0 0 3 0x14280 nfsidl nfsio 81967 196470 0 0 3 0x14280 nfsidl nfsio 24168 349318 0 0 3 0x14280 nfsidl nfsio 61355 31045 0 0 3 0x14280 nfsidl nfsio 61218 472900 0 0 3 0x14280 nfsidl nfsio 5396 164913 0 0 3 0x14280 nfsidl nfsio 96689 179122 0 0 3 0x14280 nfsidl nfsio 24100 314369 0 0 3 0x14280 nfsidl nfsio 35360 202569 0 0 3 0x14280 nfsidl nfsio 95977 52851 0 0 3 0x14280 nfsidl nfsio 27594 147372 0 0 3 0x14280 nfsidl nfsio 51067 243180 0 0 3 0x14280 nfsidl nfsio 95597 143756 0 0 3 0x14200 acct acct 15561 34736 25657 0 3 0x82 nanoslp syz-executor.7 68611 335663 25657 0 3 0x82 nanoslp syz-executor.6 40239 329835 0 0 3 0x14200 bored sosplice 56579 303373 25657 0 3 0x82 nanoslp syz-executor.0 25657 366710 49384 0 3 0x82 thrsleep syz-fuzzer 25657 375644 49384 0 3 0x4000082 nanoslp syz-fuzzer 25657 305559 49384 0 3 0x4000082 thrsleep syz-fuzzer 25657 194877 49384 0 3 0x4000082 thrsleep syz-fuzzer 25657 145139 49384 0 3 0x4000082 wait syz-fuzzer 25657 284475 49384 0 3 0x4000082 wait syz-fuzzer 25657 420518 49384 0 3 0x4000082 kqread syz-fuzzer 25657 412044 49384 0 3 0x4000082 wait syz-fuzzer 25657 498947 49384 0 3 0x4000082 thrsleep syz-fuzzer 25657 254735 49384 0 3 0x4000082 wait syz-fuzzer 25657 369152 49384 0 3 0x4000082 wait syz-fuzzer 25657 199487 49384 0 3 0x4000082 wait syz-fuzzer 25657 173973 49384 0 3 0x4000082 wait syz-fuzzer 25657 435396 49384 0 3 0x4000082 wait syz-fuzzer 49384 518427 6745 0 3 0x10008a sigsusp ksh 6745 444738 21754 0 3 0x9a kqread sshd 21754 4054 1 0 3 0x88 kqread sshd 18569 316091 19768 73 3 0x1100090 kqread syslogd 19768 336154 1 0 3 0x100082 netio syslogd 92744 338653 1 0 3 0x100080 kqread resolvd 92436 196880 80205 77 3 0x100092 kqread dhcpleased 70003 308703 80205 77 3 0x100092 kqread dhcpleased 80205 256915 1 0 3 0x80 kqread dhcpleased 6316 283418 0 0 3 0x14200 bored smr 44331 359824 0 0 2 0x14200 zerothread 17045 271603 0 0 3 0x14200 aiodoned aiodoned 98191 337227 0 0 3 0x14200 syncer update 24347 64424 0 0 3 0x14200 cleaner cleaner 435 516469 0 0 3 0x14200 reaper reaper 86302 292319 0 0 3 0x14200 pgdaemon pagedaemon 8956 339246 0 0 3 0x14200 bored viomb 41982 349694 0 0 3 0x40014200 acpi0 acpi0 68799 506907 0 0 3 0x14200 bored softnet 6384 112961 0 0 3 0x14200 bored softnet 7605 124456 0 0 3 0x14200 bored softnet 9455 206449 0 0 3 0x14200 bored softnet 51484 346704 0 0 3 0x14200 bored systqmp 64564 202354 0 0 3 0x14200 bored systq 80951 12231 0 0 3 0x40014200 bored softclock 97762 91041 0 0 3 0x40014200 idle0 1 53590 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 10207 6432K 7143K 78643K 19617 0 pcb 13 18K 20K 78643K 943 0 rtable 211 17K 19K 78643K 2710 0 ifaddr 99 21K 21K 78643K 595 0 sysctl 3 1K 1K 78643K 3 0 counters 26 17K 17K 78643K 102 0 ioctlops 0 0K 4K 78643K 6526 0 iov 0 0K 20K 78643K 561 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 4 0 vnodes 1330 83K 83K 78643K 3630 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 9K 78643K 63 0 VM map 2 0K 0K 78643K 2 0 sem 12 0K 0K 78643K 392 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12548 0 file desc 15 53K 73K 78643K 11151 0 sigio 0 0K 0K 78643K 350 0 proc 60 59K 83K 78643K 1465 0 subproc 104 6K 6K 78643K 364 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 2 0K 1K 78643K 9078 0 in_multi 81 5K 6K 78643K 1564 0 ether_multi 1 0K 0K 78643K 442 0 mrt 1 0K 0K 78643K 13 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 163 731K 731K 78643K 163 0 exec 0 0K 2K 78643K 1506 0 tdb 3 0K 0K 78643K 3 0 pagedep 1 8K 8K 78643K 1 0 inodedep 1 32K 32K 78643K 1 0 newblk 1 0K 0K 78643K 1 0 VM swap 8 62K 62K 78643K 8 0 UVM amap 362 384K 400K 78643K 58461 0 UVM aobj 131 4K 4K 78643K 131 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 107 0 NDP 14 0K 2K 78643K 150 0 temp 136 4718K 5742K 78643K 75943 0 kqueue 13 18K 25K 78643K 685 0 SYN cache 2 16K 16K 78643K 2 0 ddb> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle rtpcb 120 850 0 847 12 11 1 3 0 8 0 rtentry 112 893 0 808 4 1 3 4 0 8 0 unpcb 144 5131 0 5118 49 48 1 10 0 8 0 syncache 296 38 0 38 9 9 0 1 0 8 0 sackhl 24 1 0 1 1 1 0 1 0 8 0 tcpqe 32 307 0 307 5 5 0 1 0 8 0 tcpcb 736 5108 0 5104 82 81 1 18 0 8 0 arp 88 60 0 45 1 0 1 1 0 8 0 ipq 40 1 0 1 1 1 0 1 0 8 0 ipqe 40 4 0 4 1 1 0 1 0 8 0 inpcb 320 26205 0 26194 201 191 10 23 0 8 8 ip6q 72 2 0 2 1 1 0 1 0 8 0 ip6af 40 4 0 4 1 1 0 1 0 8 0 nd6 48 96 0 76 1 0 1 1 0 8 0 pkpcb 40 82 0 82 3 3 0 1 0 8 0 kcovpl 48 28 0 20 1 0 1 1 0 8 0 ppxss 1160 32 0 32 6 6 0 1 0 8 0 pfstscr 40 33 0 33 2 2 0 1 0 8 0 pfosfp 40 4 0 3 2 1 1 1 0 8 0 pfosfpen 112 4 0 3 2 1 1 1 0 8 0 pfrktable 1344 97 0 92 3 2 1 1 0 8 0 pfanchor 1280 84 0 34 6 1 5 5 0 8 0 pftag 88 20 0 16 1 0 1 1 0 8 0 pfqueue 264 4 0 4 2 2 0 1 0 8 0 pfstitem 24 46 0 46 1 1 0 1 0 8 0 pfstkey 120 87 0 87 2 2 0 1 0 8 0 pfstate 336 45 0 45 2 2 0 1 0 8 0 pfrule 1360 134 0 108 5 2 3 3 0 8 0 art_heap8 4096 519 0 517 3 1 2 3 0 8 0 art_heap4 256 4822 0 4421 45 19 26 32 0 8 0 art_table 32 5341 0 4938 6 2 4 5 0 8 0 art_node 16 892 0 818 1 0 1 1 0 8 0 sysvmsgpl 40 81 0 71 1 0 1 1 0 8 0 semapl 112 390 0 380 1 0 1 1 0 8 0 shmpl 112 128 0 0 4 0 4 4 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 14101 0 12645 92 0 92 92 0 8 0 ffsino 240 14101 0 12645 86 0 86 86 0 8 0 nchpl 144 27506 0 25855 63 1 62 63 0 8 0 uvmvnodes 80 5926 0 0 121 0 121 121 0 8 0 vnodes 216 5926 0 0 330 0 330 330 0 8 0 namei 1024 92844 0 92843 4 3 1 2 0 8 0 vcpupl 2048 19 0 0 3 0 3 3 0 8 0 vmpool 536 38 0 19 2 0 2 2 0 8 0 pfiaddrpl 120 35 0 28 3 2 1 1 0 8 0 kstatmem 264 180 0 152 5 2 3 3 0 8 0 scsiplug 72 3 0 3 1 1 0 1 0 8 0 scxspl 216 78485 0 78484 18 17 1 8 0 8 0 plimitpl 152 471 0 457 1 0 1 1 0 8 0 sigapl 424 11424 0 11358 8 0 8 8 0 8 0 futexpl 64 108572 0 108568 1 0 1 1 0 8 0 knotepl 120 95566 0 95485 26 23 3 7 0 8 0 kqueuepl 184 2735 0 2726 32 31 1 4 0 8 0 pipepl 288 2133 0 2103 56 53 3 9 0 8 0 fdescpl 432 11386 0 11360 5 1 4 4 0 8 0 filepl 120 74863 0 74615 71 59 12 17 0 8 4 lockfpl 104 2009 0 2006 5 4 1 2 0 8 0 lockfspl 48 593 0 590 1 0 1 1 0 8 0 sessionpl 144 44 0 28 1 0 1 1 0 8 0 pgrppl 48 187 0 171 1 0 1 1 0 8 0 ucredpl 104 4629 0 4614 1 0 1 1 0 8 0 zombiepl 144 11360 0 11358 2 1 1 1 0 8 0 processpl 1000 11424 0 11358 9 0 9 9 0 8 0 procpl 672 26429 0 26345 20 12 8 9 0 8 0 sosppl 168 44 0 44 7 7 0 1 0 8 0 sockpl 456 32280 0 32256 556 545 11 36 0 8 7 mcl64k 65536 378 0 378 11 10 1 1 0 8 1 mcl16k 16384 103 0 103 16 16 0 1 0 8 0 mcl12k 12288 1055 0 1055 6 5 1 1 0 8 1 mcl9k 9216 132 0 132 17 17 0 1 0 8 0 mcl8k 8192 555 0 555 7 6 1 1 0 8 1 mcl4k 4096 1067 0 1067 4 3 1 1 0 8 1 mcl2k2 2112 75 0 75 10 9 1 1 0 8 1 mcl2k 2048 91636 0 91559 28 17 11 17 0 8 0 mtagpl 96 810 0 460 13 4 9 10 0 8 0 mbufpl 256 227303 0 226740 94 56 38 58 0 8 0 bufpl 288 17888 0 11484 458 0 458 458 0 8 0 anonpl 24 1966603 0 1950807 210 95 115 126 0 188 6 amapchunkpl 152 170821 0 170202 73 46 27 39 0 158 0 amappl16 200 27979 0 27353 117 83 34 46 0 8 0 amappl15 192 3645 0 3635 1 0 1 1 0 8 0 amappl14 184 2214 0 2207 1 0 1 1 0 8 0 amappl13 176 2671 0 2663 1 0 1 1 0 8 0 amappl12 168 69 0 65 1 0 1 1 0 8 0 amappl11 160 1432 0 1416 1 0 1 1 0 8 0 amappl10 152 995 0 994 1 0 1 1 0 8 0 amappl9 144 2666 0 2663 1 0 1 1 0 8 0 amappl8 136 1268 0 1159 4 0 4 4 0 8 0 amappl7 128 363 0 341 1 0 1 1 0 8 0 amappl6 120 2552 0 2541 2 1 1 2 0 8 0 amappl5 112 6687 0 6676 1 0 1 1 0 8 0 amappl4 104 5796 0 5762 2 1 1 2 0 8 0 amappl3 96 34193 0 34138 2 0 2 2 0 8 0 amappl2 88 3296 0 3257 2 0 2 2 0 8 0 amappl1 80 275351 0 274724 20 5 15 19 0 8 1 amappl 88 57453 0 57281 5 0 5 5 0 92 0 dma4096 4096 1 0 1 1 1 0 1 0 8 0 dma1024 1024 1 0 0 1 0 1 1 0 8 0 dma256 256 6 0 6 1 1 0 1 0 8 0 dma128 128 253 0 253 1 1 0 1 0 8 0 dma64 64 6 0 6 1 1 0 1 0 8 0 dma32 32 7 0 7 1 1 0 1 0 8 0 dma16 16 18 0 17 1 0 1 1 0 8 0 aobjpl 72 130 0 0 3 0 3 3 0 8 0 uaddrrnd 24 11424 0 11379 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 11424 0 11379 1 0 1 1 0 8 0 vmmpekpl 168 75881 0 75831 3 0 3 3 0 8 0 vmmpepl 168 1079121 0 1076554 233 108 125 134 0 357 1 vmsppl 272 11423 0 11379 5 1 4 4 0 8 0 rwobjpl 24 255873 0 248167 52 4 48 49 0 8 0 pdppl 4096 22854 0 22777 447 364 83 83 0 8 6 pvpl 32 3812032 0 3791916 369 176 193 255 0 265 18 pmappl 216 11423 0 11379 4 1 3 3 0 8 0 extentpl 40 56 0 38 1 0 1 1 0 8 0 phpool 112 1454 0 636 25 0 25 25 0 8 0 ddb> machine ddbcpu 0 No such command ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff8256db42) at panic+0x161 sys/kern/subr_prf.c:202 malloc(194,e,1) at malloc+0xa85 sys/kern/kern_malloc.c:363 sys_ioctl(ffff8000ffff8548,ffff80002e9910d8,ffff80002e991130) at sys_ioctl+0x2b1 syscall(ffff80002e9911a0) at syscall+0x447 sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xdd52b848f20, count: -6 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:437 panic(ffffffff8256db42) at panic+0x161 sys/kern/subr_prf.c:202 malloc(194,e,1) at malloc+0xa85 sys/kern/kern_malloc.c:363 sys_ioctl(ffff8000ffff8548,ffff80002e9910d8,ffff80002e991130) at sys_ioctl+0x2b1 syscall(ffff80002e9911a0) at syscall+0x447 sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xdd52b848f20, count: -6