panic: Data modified on freelist: word 4 of object 0xffff800000a10000 size 0x800 previous type free (0x0 != 0xdeadbeef) Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *111331 86584 0 0 0x4000000 0 syz-executor.1 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff821a93c9) at panic+0x15c sys/kern/subr_prf.c:207 malloc(800,7f,1) at malloc+0xa23 sys/kern/kern_malloc.c:331 knote_attach(fffffd805db63380) at knote_attach+0xaf sys/kern/kern_event.c:1119 kqueue_register(fffffd805d71da28,ffff80001e43e960,ffff8000ffff2290) at kqueue_register+0x36c sys/kern/kern_event.c:680 sys_kevent(ffff8000ffff2290,ffff80001e43eb08,ffff80001e43eb50) at sys_kevent+0x2b1 sys/kern/kern_event.c:522 syscall(ffff80001e43ebd0) at syscall+0x507 sys/arch/amd64/amd64/trap.c:555 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x87f7fe051c0, count: 7 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 Data modified on freelist: word 4 of object 0xffff800000a10000 size 0x800 previous type free (0x0 != 0xdeadbeef) ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff821a93c9) at panic+0x15c sys/kern/subr_prf.c:207 malloc(800,7f,1) at malloc+0xa23 sys/kern/kern_malloc.c:331 knote_attach(fffffd805db63380) at knote_attach+0xaf sys/kern/kern_event.c:1119 kqueue_register(fffffd805d71da28,ffff80001e43e960,ffff8000ffff2290) at kqueue_register+0x36c sys/kern/kern_event.c:680 sys_kevent(ffff8000ffff2290,ffff80001e43eb08,ffff80001e43eb50) at sys_kevent+0x2b1 sys/kern/kern_event.c:522 syscall(ffff80001e43ebd0) at syscall+0x507 sys/arch/amd64/amd64/trap.c:555 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x87f7fe051c0, count: -8 ddb> show registers rdi 0xffffffff81c29ac7 db_enter+0x17 rsi 0x7e63 __ALIGN_SIZE+0x6e63 rbp 0xffff80001e43e6c0 rbx 0xffff80001e43e770 rdx 0x7e64 __ALIGN_SIZE+0x6e64 rcx 0xffff80001f63f000 rax 0xffff80001f63f000 r8 0xffff80001e43e680 r9 0x1 r10 0xffff8000009f7180 r11 0xea38f1f288441743 r12 0x3000000008 r13 0xffff80001e43e6d0 r14 0x100 r15 0x1 rip 0xffffffff81c29ac8 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff80001e43e6b0 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (syz-executor.1) pid=111331 stat=onproc flags process=0 proc=4000000 pri=86, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff8000ffff3650,0xffffffff825498a0 process=0xffff8000ffff6378 user=0xffff80001e439000, vmspace=0xfffffd806bc09cc0 estcpu=36, cpticks=2, pctcpu=0.0 user=0, sys=2, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 86584 220316 94604 0 2 0 syz-executor.1 *86584 111331 94604 0 7 0x4000000 syz-executor.1 94604 120317 98924 0 3 0x82 nanosleep syz-executor.1 50914 298598 98924 0 3 0x82 nanosleep syz-executor.0 98924 504715 94741 0 3 0x82 thrsleep syz-fuzzer 98924 159912 94741 0 3 0x4000082 thrsleep syz-fuzzer 98924 150601 94741 0 3 0x4000082 thrsleep syz-fuzzer 98924 315383 94741 0 3 0x4000082 thrsleep syz-fuzzer 98924 176788 94741 0 3 0x4000082 kqread syz-fuzzer 98924 274295 94741 0 3 0x4000082 thrsleep syz-fuzzer 98924 79076 94741 0 3 0x4000082 thrsleep syz-fuzzer 94741 342994 9228 0 3 0x10008a pause ksh 9228 399295 86539 0 3 0x92 select sshd 47845 501335 1 0 3 0x100083 ttyin getty 86539 451949 1 0 3 0x80 select sshd 74007 312010 96871 73 3 0x100090 kqread syslogd 96871 142454 1 0 3 0x100082 netio syslogd 47805 522314 1 77 3 0x100090 poll dhclient 87738 359950 1 0 3 0x80 poll dhclient 55136 439425 0 0 2 0x14200 zerothread 78317 404192 0 0 3 0x14200 aiodoned aiodoned 23629 337226 0 0 3 0x14200 syncer update 31333 45541 0 0 3 0x14200 cleaner cleaner 63007 137176 0 0 3 0x14200 reaper reaper 81999 487692 0 0 3 0x14200 pgdaemon pagedaemon 42579 219584 0 0 3 0x14200 bored crynlk 13177 474269 0 0 3 0x14200 bored crypto 75865 116082 0 0 3 0x40014200 acpi0 acpi0 33520 375202 0 0 3 0x14200 bored softnet 37628 71593 0 0 3 0x14200 bored systqmp 20629 129183 0 0 3 0x14200 bored systq 36786 79792 0 0 3 0x40014200 bored softclock 13948 503072 0 0 3 0x40014200 idle0 43332 448173 0 0 3 0x14200 bored smr 1 103854 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 9455 6453K 6785K 78643K 10674 0 pcb 13 8K 8K 78643K 23 0 rtable 105 3K 3K 78643K 202 0 ifaddr 41 10K 10K 78643K 47 0 counters 19 16K 16K 78643K 19 0 ioctlops 0 0K 2K 78643K 19 0 iov 0 0K 16K 78643K 4 0 mount 1 1K 1K 78643K 1 0 vnodes 1223 77K 77K 78643K 1257 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 1K 78643K 2 0 VM map 2 0K 0K 78643K 2 0 sem 12 0K 0K 78643K 32 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1794 195K 288K 78643K 12646 0 file desc 5 13K 25K 78643K 61 0 sigio 0 0K 0K 78643K 2 0 proc 47 38K 63K 78643K 358 0 subproc 32 2K 2K 78643K 34 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 in_multi 40 2K 2K 78643K 40 0 ether_multi 1 0K 0K 78643K 1 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 37 175K 175K 78643K 37 0 exec 0 0K 1K 78643K 191 0 pagedep 1 8K 8K 78643K 1 0 inodedep 1 32K 32K 78643K 1 0 newblk 1 0K 0K 78643K 1 0 VM swap 7 26K 26K 78643K 7 0 UVM amap 108 21K 22K 78643K 981 0 UVM aobj 8 2K 2K 78643K 8 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 5 0 NDP 5 0K 0K 78643K 10 0 temp 73 3012K 3074K 78643K 3304 0 kqueue 0 0K 0K 78643K 2 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 arp 64 6 0 0 1 0 1 1 0 8 0 rtpcb 80 21 0 19 1 0 1 1 0 8 0 rtentry 112 45 0 1 2 0 2 2 0 8 0 unpcb 120 45 0 37 1 0 1 1 0 8 0 syncache 264 4 0 4 1 1 0 1 0 8 0 tcpqe 32 18 0 18 1 0 1 1 0 8 1 tcpcb 544 40 0 36 2 0 2 2 0 8 1 inpcb 280 120 0 113 3 0 3 3 0 8 2 nd6 48 4 0 0 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 212 0 0 14 0 14 14 0 8 0 art_table 32 213 0 0 2 0 2 2 0 8 0 art_node 16 44 0 4 1 0 1 1 0 8 0 sysvmsgpl 40 8 0 4 1 0 1 1 0 8 0 semapl 112 30 0 20 1 0 1 1 0 8 0 shmpl 112 6 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino1pl 128 1467 0 64 46 0 46 46 0 8 0 ffsino 240 1467 0 64 83 0 83 83 0 8 0 nchpl 144 1734 0 119 60 0 60 60 0 8 0 uvmvnodes 72 1540 0 0 28 0 28 28 0 8 0 vnodes 208 1540 0 0 82 0 82 82 0 8 0 namei 1024 4262 0 4262 1 0 1 1 0 8 1 vmpool 528 2 0 2 1 0 1 1 0 8 1 scxspl 192 4568 0 4568 1 0 1 1 0 8 1 plimitpl 152 14 0 7 1 0 1 1 0 8 0 sigapl 432 232 0 219 2 0 2 2 0 8 0 futexpl 56 1194 0 1194 1 0 1 1 0 8 1 knotepl 112 70 0 50 1 0 1 1 0 8 0 kqueuepl 104 17 0 14 1 0 1 1 0 8 0 pipepl 112 158 0 139 1 0 1 1 0 8 0 fdescpl 424 233 0 219 2 0 2 2 0 8 0 filepl 120 1345 0 1248 5 0 5 5 0 8 2 lockfpl 104 8 0 7 1 0 1 1 0 8 0 lockfspl 48 4 0 3 1 0 1 1 0 8 0 sessionpl 112 17 0 7 1 0 1 1 0 8 0 pgrppl 48 17 0 7 1 0 1 1 0 8 0 ucredpl 96 54 0 46 1 0 1 1 0 8 0 zombiepl 144 219 0 218 1 0 1 1 0 8 0 processpl 872 247 0 218 4 0 4 4 0 8 0 procpl 632 290 0 254 4 0 4 4 0 8 0 sockpl 384 186 0 169 7 0 7 7 0 8 5 mcl16k 16384 2 0 2 1 0 1 1 0 8 1 mcl4k 4096 11 0 11 2 1 1 1 0 8 1 mcl2k2 2112 2 0 2 1 0 1 1 0 8 1 mcl2k 2048 69332 0 69288 16 2 14 14 0 8 7 mtagpl 80 2 0 2 1 1 0 1 0 8 0 mbufpl 256 109479 0 109406 10 1 9 9 0 8 0 bufpl 280 6211 0 1326 349 0 349 349 0 8 0 anonpl 16 44339 0 25982 92 2 90 90 0 107 16 amapchunkpl 152 1202 0 1050 8 0 8 8 0 158 1 amappl16 192 1398 0 394 63 4 59 63 0 8 8 amappl15 184 50 0 46 1 0 1 1 0 8 0 amappl14 176 26 0 24 1 0 1 1 0 8 0 amappl13 168 8 0 7 1 0 1 1 0 8 0 amappl12 160 18 0 17 2 1 1 1 0 8 0 amappl11 152 46 0 34 1 0 1 1 0 8 0 amappl10 144 21 0 17 1 0 1 1 0 8 0 amappl9 136 565 0 560 1 0 1 1 0 8 0 amappl8 128 117 0 95 1 0 1 1 0 8 0 amappl7 120 91 0 80 1 0 1 1 0 8 0 amappl6 112 52 0 47 1 0 1 1 0 8 0 amappl5 104 165 0 156 1 0 1 1 0 8 0 amappl4 96 444 0 416 1 0 1 1 0 8 0 amappl3 88 114 0 107 1 0 1 1 0 8 0 amappl2 80 1073 0 1003 3 0 3 3 0 8 1 amappl1 72 14072 0 13650 25 9 16 20 0 8 7 amappl 80 512 0 469 1 0 1 1 0 84 0 dma4096 4096 1 0 1 1 1 0 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 64 7 0 0 1 0 1 1 0 8 0 uaddrrnd 24 235 0 221 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 235 0 221 1 0 1 1 0 8 0 vmmpekpl 168 5757 0 5734 2 0 2 2 0 8 0 vmmpepl 168 36544 0 34448 130 4 126 126 0 357 33 vmsppl 272 234 0 221 2 0 2 2 0 8 1 pdppl 4096 476 0 442 6 0 6 6 0 8 1 pvpl 32 135345 0 114031 209 0 209 209 0 265 37 pmappl 200 234 0 221 1 0 1 1 0 8 0 extentpl 40 46 0 29 1 0 1 1 0 8 0 phpool 112 143 0 6 4 0 4 4 0 8 0