panic: Data modified on freelist: word 4 of object 0xffff800000a5d000 size 0xb1 previous type free (0x0 != 0xdeafbead) Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 395798 8608 0 0 0 0 syz-executor.0 * 14138 8608 0 0 0x4000000 1K syz-executor.0 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff821ec175) at panic+0x15c sys/kern/subr_prf.c:207 malloc(b1,5,1) at malloc+0xa23 sys/kern/kern_malloc.c:331 route_output(fffffd806320a600,fffffd8063cdc800,0,0) at route_output+0x1b3 sys/net/rtsock.c:706 route_usrreq(fffffd8063cdc800,9,fffffd806320a600,0,0,ffff800020ac6eb8) at route_usrreq+0x36f sys/net/rtsock.c:275 sosend(fffffd8063cdc800,0,ffff800021bab380,0,0,80) at sosend+0x671 sys/kern/uipc_socket.c:549 sendit(ffff800020ac6eb8,5,ffff800021bab460,0,ffff800021bab540) at sendit+0x52b sys/kern/uipc_syscalls.c:657 sys_sendto(ffff800020ac6eb8,ffff800021bab4f8,ffff800021bab540) at sys_sendto+0x80 sys/kern/uipc_syscalls.c:522 syscall(ffff800021bab5c0) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff800021bab5c0) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x26c60715400, count: 5 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{1}> ddb{1}> set $lines = 0 ddb{1}> set $maxwidth = 0 ddb{1}> show panic Data modified on freelist: word 4 of object 0xffff800000a5d000 size 0xb1 previous type free (0x0 != 0xdeafbead) ddb{1}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff821ec175) at panic+0x15c sys/kern/subr_prf.c:207 malloc(b1,5,1) at malloc+0xa23 sys/kern/kern_malloc.c:331 route_output(fffffd806320a600,fffffd8063cdc800,0,0) at route_output+0x1b3 sys/net/rtsock.c:706 route_usrreq(fffffd8063cdc800,9,fffffd806320a600,0,0,ffff800020ac6eb8) at route_usrreq+0x36f sys/net/rtsock.c:275 sosend(fffffd8063cdc800,0,ffff800021bab380,0,0,80) at sosend+0x671 sys/kern/uipc_socket.c:549 sendit(ffff800020ac6eb8,5,ffff800021bab460,0,ffff800021bab540) at sendit+0x52b sys/kern/uipc_syscalls.c:657 sys_sendto(ffff800020ac6eb8,ffff800021bab4f8,ffff800021bab540) at sys_sendto+0x80 sys/kern/uipc_syscalls.c:522 syscall(ffff800021bab5c0) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline] syscall(ffff800021bab5c0) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x26c60715400, count: -10 ddb{1}> show registers rdi 0xffffffff811a6057 db_enter+0x17 rsi 0x77a6 __ALIGN_SIZE+0x67a6 rbp 0xffff800021baaf50 rbx 0xffff800021bab000 rdx 0x77a7 __ALIGN_SIZE+0x67a7 rcx 0xffff800020b90000 rax 0xffff800020b90000 r8 0xffffffff8124a8ef kprintf+0x16f r9 0x1 r10 0x25 r11 0xdd5d1303d19bee2d r12 0x3000000008 r13 0xffff800021baaf60 r14 0x100 r15 0x1 rip 0xffffffff811a6058 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff800021baaf40 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{1}> show proc PROC (syz-executor.0) pid=14138 stat=onproc flags process=0 proc=4000000 pri=32, usrpri=76, nice=20 forw=0xffffffffffffffff, list=0xffff800020ac6288,0xffff800020ac7138 process=0xffff800020a927a0 user=0xffff800021ba6000, vmspace=0xfffffd806e9afa18 estcpu=36, cpticks=3, pctcpu=0.0 user=0, sys=2, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 81964 466404 72173 0 2 0 syz-executor.1 8608 395798 57350 0 7 0 syz-executor.0 * 8608 14138 57350 0 7 0x4000000 syz-executor.0 84079 39437 0 0 3 0x14200 bored sosplice 72173 43204 59214 0 3 0x82 nanosleep syz-executor.1 57350 484791 59214 0 3 0x82 nanosleep syz-executor.0 59214 405403 88695 0 3 0x82 thrsleep syz-fuzzer 59214 265961 88695 0 3 0x4000082 nanosleep syz-fuzzer 59214 464963 88695 0 3 0x4000082 kqread syz-fuzzer 59214 2475 88695 0 3 0x4000082 thrsleep syz-fuzzer 59214 179434 88695 0 3 0x4000082 thrsleep syz-fuzzer 59214 330826 88695 0 3 0x4000082 thrsleep syz-fuzzer 59214 285366 88695 0 3 0x4000082 thrsleep syz-fuzzer 59214 418462 88695 0 3 0x4000082 thrsleep syz-fuzzer 59214 329393 88695 0 3 0x4000082 thrsleep syz-fuzzer 59214 167748 88695 0 3 0x4000082 thrsleep syz-fuzzer 88695 139756 48504 0 3 0x10008a pause ksh 48504 40325 76137 0 3 0x92 select sshd 80053 314951 1 0 3 0x100083 ttyin getty 76137 31386 1 0 3 0x80 select sshd 95931 247530 10920 74 3 0x100092 bpf pflogd 10920 230762 1 0 3 0x80 netio pflogd 67479 225836 58670 73 3 0x100090 kqread syslogd 58670 151250 1 0 3 0x100082 netio syslogd 71356 511019 1 77 3 0x100090 poll dhclient 26180 105899 1 0 3 0x80 poll dhclient 66887 349757 0 0 3 0x14200 bored smr 39539 162808 0 0 3 0x14200 pgzero zerothread 55297 465820 0 0 3 0x14200 aiodoned aiodoned 57310 250920 0 0 3 0x14200 syncer update 56536 262176 0 0 3 0x14200 cleaner cleaner 36643 100702 0 0 3 0x14200 reaper reaper 61606 224924 0 0 3 0x14200 pgdaemon pagedaemon 67970 87706 0 0 3 0x14200 bored crynlk 32011 118383 0 0 3 0x14200 bored crypto 39751 103776 0 0 3 0x40014200 acpi0 acpi0 27687 154567 0 0 3 0x40014200 idle1 69777 478993 0 0 3 0x14200 bored softnet 80261 463279 0 0 3 0x14200 bored systqmp 45303 249657 0 0 3 0x14200 bored systq 55327 517874 0 0 3 0x40014200 bored softclock 82331 39401 0 0 3 0x40014200 idle0 1 190130 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{1}> show all locks CPU 1: exclusive mutex /syzkaller/managers/multicore/kernel/sys/kern/kern_malloc.c:104 r = 0 (0xffffffff82501ea0) #0 witness_lock+0x52e sys/kern/subr_witness.c:1164 #1 mtx_enter_try+0x102 #2 mtx_enter+0x4b sys/kern/kern_lock.c:266 #3 malloc+0x23b sys/kern/kern_malloc.c:209 #4 route_output+0x1b3 sys/net/rtsock.c:706 #5 route_usrreq+0x36f sys/net/rtsock.c:275 #6 sosend+0x671 sys/kern/uipc_socket.c:549 #7 sendit+0x52b sys/kern/uipc_syscalls.c:657 #8 sys_sendto+0x80 sys/kern/uipc_syscalls.c:522 #9 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline] #9 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 #10 Xsyscall+0x128 Process 8608 (syz-executor.0) thread 0xffff800020ac6eb8 (14138) exclusive kernel_lock &kernel_lock r = 0 (0xffffffff826848b0) #0 witness_lock+0x52e sys/kern/subr_witness.c:1164 #1 solock+0x66 sys/kern/uipc_socket2.c:292 #2 sosend+0x559 sys/kern/uipc_socket.c:537 #3 sendit+0x52b sys/kern/uipc_syscalls.c:657 #4 sys_sendto+0x80 sys/kern/uipc_syscalls.c:522 #5 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline] #5 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 #6 Xsyscall+0x128 exclusive mutex /syzkaller/managers/multicore/kernel/sys/kern/kern_malloc.c:104 r = 0 (0xffffffff82501ea0) #0 witness_lock+0x52e sys/kern/subr_witness.c:1164 #1 mtx_enter_try+0x102 #2 mtx_enter+0x4b sys/kern/kern_lock.c:266 #3 malloc+0x23b sys/kern/kern_malloc.c:209 #4 route_output+0x1b3 sys/net/rtsock.c:706 #5 route_usrreq+0x36f sys/net/rtsock.c:275 #6 sosend+0x671 sys/kern/uipc_socket.c:549 #7 sendit+0x52b sys/kern/uipc_syscalls.c:657 #8 sys_sendto+0x80 sys/kern/uipc_syscalls.c:522 #9 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:102 [inline] #9 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 #10 Xsyscall+0x128 ddb{1}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 9542 6550K 8732K 78643K 13189 0 pcb 13 8K 8K 78643K 79 0 rtable 107 3K 3K 78643K 318 0 ifaddr 83 15K 16K 78643K 138 0 counters 43 33K 34K 78643K 63 0 ioctlops 0 0K 4K 78643K 1485 0 iov 0 0K 16K 78643K 65 0 mount 1 1K 1K 78643K 1 0 vnodes 1235 78K 78K 78643K 1900 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 5K 78643K 5 0 VM map 2 1K 1K 78643K 2 0 sem 12 0K 1K 78643K 81 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1809 196K 290K 78643K 12766 0 file desc 6 17K 25K 78643K 406 0 sigio 0 0K 0K 78643K 16 0 proc 62 63K 95K 78643K 490 0 subproc 32 2K 2K 78643K 34 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 0 0K 1K 78643K 251 0 in_multi 52 2K 3K 78643K 138 0 ether_multi 1 0K 0K 78643K 9 0 mrt 0 0K 0K 78643K 4 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 43 201K 201K 78643K 43 0 exec 0 0K 1K 78643K 241 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 126 71K 71K 78643K 2200 0 UVM aobj 18 2K 2K 78643K 19 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 41 0 NDP 14 0K 0K 78643K 28 0 temp 140 3026K 3120K 78643K 7286 0 kqueue 3 4K 8K 78643K 22 0 SYN cache 2 16K 16K 78643K 2 0 ddb{1}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle arp 64 7 0 1 1 0 1 1 0 8 0 plcache 128 20 0 0 1 0 1 1 0 8 0 rtpcb 80 62 0 59 1 0 1 1 0 8 0 rtentry 112 51 0 6 2 0 2 2 0 8 0 unpcb 120 322 0 310 1 0 1 1 0 8 0 syncache 264 6 0 6 2 2 0 1 0 8 0 sackhl 24 2 0 2 1 0 1 1 0 8 1 tcpqe 32 5 0 5 1 1 0 1 0 8 0 tcpcb 544 155 0 151 2 1 1 2 0 8 0 inpcb 280 513 0 506 3 1 2 2 0 8 1 rttmr 72 2 0 2 1 1 0 1 0 8 0 nd6 48 7 0 0 1 0 1 1 0 8 0 pkpcb 40 2 0 2 1 1 0 1 0 8 0 pffrag 232 3 0 2 1 0 1 1 0 482 0 pffrnode 88 3 0 2 1 0 1 1 0 8 0 pffrent 40 123 0 88 1 0 1 1 0 8 0 pfosfp 40 846 0 423 5 0 5 5 0 8 0 pfosfpen 112 1428 0 714 21 0 21 21 0 8 0 pfstitem 24 51 0 8 1 0 1 1 0 8 0 pfstkey 112 51 0 8 2 0 2 2 0 8 0 pfstate 328 51 0 7 4 0 4 4 0 8 0 pfrule 1360 21 0 16 2 1 1 2 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 210 0 2 13 0 13 13 0 8 0 art_table 32 211 0 2 2 0 2 2 0 8 0 art_node 16 50 0 9 1 0 1 1 0 8 0 sysvmsgpl 40 36 0 21 1 0 1 1 0 8 0 semapl 112 75 0 65 1 0 1 1 0 8 0 shmpl 112 17 0 1 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino1pl 128 1945 0 538 46 0 46 46 0 8 0 ffsino 272 1945 0 538 95 0 95 95 0 8 0 nchpl 144 2697 0 1076 61 0 61 61 0 8 0 uvmvnodes 72 2610 0 0 48 0 48 48 0 8 0 vnodes 208 2610 0 0 138 0 138 138 0 8 0 namei 1024 7799 0 7799 1 0 1 1 0 8 1 percpumem 16 42 0 10 1 0 1 1 0 8 0 vcpupl 1984 6 0 0 1 0 1 1 0 8 0 vmpool 560 8 0 2 1 0 1 1 0 8 0 scsiplug 64 1 0 1 1 1 0 1 0 8 0 scxspl 192 8295 0 8295 10 7 3 7 0 8 3 plimitpl 152 39 0 31 1 0 1 1 0 8 0 sigapl 424 622 0 589 4 0 4 4 0 8 0 futexpl 56 7416 0 7416 1 0 1 1 0 8 1 knotepl 112 74 0 55 1 0 1 1 0 8 0 kqueuepl 144 53 0 51 1 0 1 1 0 8 0 pipelkpl 48 139 0 129 1 0 1 1 0 8 0 pipepl 120 278 0 259 1 0 1 1 0 8 0 fdescpl 496 606 0 589 3 0 3 3 0 8 0 filepl 152 4005 0 3902 6 0 6 6 0 8 2 lockfpl 104 78 0 77 1 0 1 1 0 8 0 lockfspl 48 35 0 34 1 0 1 1 0 8 0 sessionpl 112 18 0 7 1 0 1 1 0 8 0 pgrppl 48 26 0 15 1 0 1 1 0 8 0 ucredpl 96 354 0 345 1 0 1 1 0 8 0 zombiepl 144 589 0 589 1 0 1 1 0 8 1 processpl 960 622 0 589 5 0 5 5 0 8 0 procpl 624 1410 0 1367 4 0 4 4 0 8 0 sosppl 128 11 0 11 2 2 0 1 0 8 0 sockpl 400 902 0 880 7 3 4 6 0 8 1 mcl64k 65536 19 0 0 3 0 3 3 0 8 0 mcl16k 16384 1 0 0 1 0 1 1 0 8 0 mcl12k 12288 4 0 0 1 0 1 1 0 8 0 mcl9k 9216 2 0 0 1 0 1 1 0 8 0 mcl8k 8192 6 0 0 1 0 1 1 0 8 0 mcl4k 4096 5 0 0 1 0 1 1 0 8 0 mcl2k2 2112 3 0 0 1 0 1 1 0 8 0 mcl2k 2048 164 0 0 20 0 20 20 0 8 0 mtagpl 80 293 0 0 6 0 6 6 0 8 0 mbufpl 256 1020 0 0 63 0 63 63 0 8 0 bufpl 280 4778 0 178 329 0 329 329 0 8 0 anonpl 16 69950 0 52198 81 1 80 80 0 124 7 amapchunkpl 152 3153 0 3004 14 3 11 11 0 158 4 amappl16 192 2829 0 1861 50 0 50 50 0 8 1 amappl15 184 4 0 2 1 0 1 1 0 8 0 amappl14 176 213 0 212 2 1 1 1 0 8 0 amappl13 168 26 0 24 1 0 1 1 0 8 0 amappl12 160 12 0 11 1 0 1 1 0 8 0 amappl11 152 77 0 59 1 0 1 1 0 8 0 amappl10 144 177 0 170 1 0 1 1 0 8 0 amappl9 136 395 0 391 1 0 1 1 0 8 0 amappl8 128 338 0 303 2 0 2 2 0 8 0 amappl7 120 281 0 268 1 0 1 1 0 8 0 amappl6 112 30 0 25 2 1 1 1 0 8 0 amappl5 104 512 0 494 1 0 1 1 0 8 0 amappl4 96 501 0 467 2 1 1 2 0 8 0 amappl3 88 327 0 322 1 0 1 1 0 8 0 amappl2 80 3916 0 3846 3 1 2 3 0 8 0 amappl1 72 22117 0 21685 25 15 10 20 0 8 0 amappl 80 1674 0 1624 2 0 2 2 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 18 0 1 1 0 1 1 0 8 0 uaddrrnd 24 614 0 591 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 614 0 591 1 0 1 1 0 8 0 vmmpekpl 168 8599 0 8568 2 0 2 2 0 8 0 vmmpepl 168 79573 0 77370 125 26 99 118 0 357 3 vmsppl 368 613 0 591 3 0 3 3 0 8 1 pdppl 4096 1236 0 1188 7 0 7 7 0 8 0 pvpl 32 225874 0 204960 194 3 191 191 0 265 20 pmappl 232 613 0 591 2 0 2 2 0 8 0 extentpl 40 46 0 29 1 0 1 1 0 8 0 phpool 112 229 0 7 7 0 7 7 0 8 0