panic: Data modified on freelist: word 4 of object 0xffff800000a6e000 size 0x2000 previous type free (0x0 != 0xdead4110) Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 183022 85222 0 0 0 0 syz-executor.1 *463111 24051 0 0 0x4000000 1K syz-executor.0 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff821c7ca8) at panic+0x15c sys/kern/subr_prf.c:207 malloc(2000,29,1) at malloc+0xa23 sys/kern/kern_malloc.c:331 unveil_check_component(ffff800020ac9650,ffff800023bab7a8,fffffd8066a0e0e8) at unveil_check_component+0x103 unveil_save_traversed_vnode sys/kern/kern_unveil.c:85 [inline] unveil_check_component(ffff800020ac9650,ffff800023bab7a8,fffffd8066a0e0e8) at unveil_check_component+0x103 sys/kern/kern_unveil.c:818 namei(ffff800023bab7a8) at namei+0x432 sys/kern/vfs_lookup.c:221 sys_unveil(ffff800020ac9650,ffff800023bab8f8,ffff800023bab940) at sys_unveil+0x240 sys/kern/vfs_syscalls.c:1015 syscall(ffff800023bab9c0) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline] syscall(ffff800023bab9c0) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72627d40f20, 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{1}> ddb{1}> set $lines = 0 ddb{1}> set $maxwidth = 0 ddb{1}> show panic Data modified on freelist: word 4 of object 0xffff800000a6e000 size 0x2000 previous type free (0x0 != 0xdead4110) ddb{1}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff821c7ca8) at panic+0x15c sys/kern/subr_prf.c:207 malloc(2000,29,1) at malloc+0xa23 sys/kern/kern_malloc.c:331 unveil_check_component(ffff800020ac9650,ffff800023bab7a8,fffffd8066a0e0e8) at unveil_check_component+0x103 unveil_save_traversed_vnode sys/kern/kern_unveil.c:85 [inline] unveil_check_component(ffff800020ac9650,ffff800023bab7a8,fffffd8066a0e0e8) at unveil_check_component+0x103 sys/kern/kern_unveil.c:818 namei(ffff800023bab7a8) at namei+0x432 sys/kern/vfs_lookup.c:221 sys_unveil(ffff800020ac9650,ffff800023bab8f8,ffff800023bab940) at sys_unveil+0x240 sys/kern/vfs_syscalls.c:1015 syscall(ffff800023bab9c0) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline] syscall(ffff800023bab9c0) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x72627d40f20, count: -8 ddb{1}> show registers rdi 0xffffffff81de4b67 db_enter+0x17 rsi 0x71cc __ALIGN_SIZE+0x61cc rbp 0xffff800023bab4e0 rbx 0xffff800023bab590 rdx 0x71cd __ALIGN_SIZE+0x61cd rcx 0xffff800020b7c000 rax 0xffff800020b7c000 r8 0xffffffff817df38f kprintf+0x16f r9 0x1 r10 0x25 r11 0x7ec5cf19c50e8cd8 r12 0x3000000008 r13 0xffff800023bab4f0 r14 0x100 r15 0x1 rip 0xffffffff81de4b68 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff800023bab4d0 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{1}> show proc PROC (syz-executor.0) pid=463111 stat=onproc flags process=0 proc=4000000 pri=86, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff800020ac8018,0xffff800020ac8a08 process=0xffff800020af5180 user=0xffff800023ba6000, vmspace=0xfffffd807f000730 estcpu=36, cpticks=2, pctcpu=0.0 user=0, sys=2, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 85222 183022 77937 0 7 0 syz-executor.1 85222 392906 77937 0 3 0x4000080 lockf syz-executor.1 24051 72558 52449 0 2 0 syz-executor.0 *24051 463111 52449 0 7 0x4000000 syz-executor.0 24051 436370 52449 0 3 0x4000080 fsleep syz-executor.0 65743 13837 0 0 3 0x14200 bored sosplice 77937 452179 70648 0 3 0x82 nanosleep syz-executor.1 52449 438957 70648 0 3 0x82 nanosleep syz-executor.0 70648 98113 16027 0 3 0x82 thrsleep syz-fuzzer 70648 362771 16027 0 3 0x4000082 thrsleep syz-fuzzer 70648 139711 16027 0 3 0x4000082 thrsleep syz-fuzzer 70648 327725 16027 0 3 0x4000082 thrsleep syz-fuzzer 70648 315886 16027 0 3 0x4000082 thrsleep syz-fuzzer 70648 468440 16027 0 3 0x4000082 kqread syz-fuzzer 70648 5159 16027 0 3 0x4000082 thrsleep syz-fuzzer 70648 134920 16027 0 3 0x4000082 thrsleep syz-fuzzer 70648 94328 16027 0 3 0x4000082 thrsleep syz-fuzzer 70648 401043 16027 0 3 0x4000082 thrsleep syz-fuzzer 16027 291106 84460 0 3 0x10008a pause ksh 84460 412535 19827 0 3 0x92 select sshd 61150 396696 1 0 3 0x100083 ttyin getty 19827 111318 1 0 3 0x80 select sshd 26618 484106 57992 74 3 0x100092 bpf pflogd 57992 342384 1 0 3 0x80 netio pflogd 82350 374515 78753 73 3 0x100090 kqread syslogd 78753 344482 1 0 3 0x100082 netio syslogd 59590 372011 1 77 3 0x100090 poll dhclient 86463 256100 1 0 3 0x80 poll dhclient 16217 211527 0 0 2 0x14200 zerothread 33294 514748 0 0 3 0x14200 aiodoned aiodoned 68689 91126 0 0 3 0x14200 syncer update 74258 377235 0 0 3 0x14200 cleaner cleaner 34419 522276 0 0 3 0x14200 reaper reaper 20276 109842 0 0 3 0x14200 pgdaemon pagedaemon 22117 156517 0 0 3 0x14200 bored crynlk 94852 434675 0 0 3 0x14200 bored crypto 54159 59025 0 0 3 0x40014200 acpi0 acpi0 35373 202999 0 0 3 0x40014200 idle1 41089 517634 0 0 3 0x14200 bored softnet 74404 78894 0 0 3 0x14200 bored systqmp 28209 284940 0 0 3 0x14200 bored systq 39268 55792 0 0 3 0x40014200 bored softclock 20505 433517 0 0 3 0x40014200 idle0 70051 481077 0 0 3 0x14200 bored smr 1 247184 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 (0xffffffff824edde0) #0 witness_lock+0x52e sys/kern/subr_witness.c:1163 #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 unveil_check_component+0x103 unveil_save_traversed_vnode sys/kern/kern_unveil.c:85 [inline] #4 unveil_check_component+0x103 sys/kern/kern_unveil.c:818 #5 namei+0x432 sys/kern/vfs_lookup.c:221 #6 sys_unveil+0x240 sys/kern/vfs_syscalls.c:1015 #7 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline] #7 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 #8 Xsyscall+0x128 Process 24051 (syz-executor.0) thread 0xffff800020ac9650 (463111) exclusive kernel_lock &kernel_lock r = 0 (0xffffffff8265aa08) #0 witness_lock+0x52e sys/kern/subr_witness.c:1163 #1 syscall+0x400 mi_syscall sys/sys/syscall_mi.h:83 [inline] #1 syscall+0x400 sys/arch/amd64/amd64/trap.c:570 #2 Xsyscall+0x128 exclusive mutex /syzkaller/managers/multicore/kernel/sys/kern/kern_malloc.c:104 r = 0 (0xffffffff824edde0) #0 witness_lock+0x52e sys/kern/subr_witness.c:1163 #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 unveil_check_component+0x103 unveil_save_traversed_vnode sys/kern/kern_unveil.c:85 [inline] #4 unveil_check_component+0x103 sys/kern/kern_unveil.c:818 #5 namei+0x432 sys/kern/vfs_lookup.c:221 #6 sys_unveil+0x240 sys/kern/vfs_syscalls.c:1015 #7 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline] #7 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:570 #8 Xsyscall+0x128 ddb{1}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 9509 6539K 7305K 78643K 11043 0 pcb 13 8K 9K 78643K 84 0 rtable 95 4K 4K 78643K 313 0 ifaddr 60 12K 12K 78643K 117 0 counters 39 33K 33K 78643K 39 0 ioctlops 0 0K 4K 78643K 1476 0 iov 0 0K 32K 78643K 25 0 mount 1 1K 1K 78643K 1 0 vnodes 1232 77K 78K 78643K 1374 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 5K 78643K 3 0 VM map 2 1K 1K 78643K 2 0 sem 11 1K 1K 78643K 15 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1809 196K 290K 78643K 12766 0 file desc 6 17K 25K 78643K 154 0 sigio 0 0K 0K 78643K 6 0 proc 62 71K 95K 78643K 446 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 0K 78643K 27 0 in_multi 31 2K 2K 78643K 70 0 ether_multi 1 0K 0K 78643K 3 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 55 254K 254K 78643K 55 0 exec 0 0K 1K 78643K 222 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 117 24K 24K 78643K 1446 0 UVM aobj 15 2K 2K 78643K 15 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 19 0 NDP 10 0K 0K 78643K 26 0 temp 123 3018K 3082K 78643K 4220 0 kqueue 3 4K 9K 78643K 21 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 6 0 2 1 0 1 1 0 8 0 plcache 128 20 0 0 1 0 1 1 0 8 0 rtpcb 80 27 0 25 1 0 1 1 0 8 0 rtentry 112 53 0 17 2 0 2 2 0 8 0 unpcb 120 124 0 114 1 0 1 1 0 8 0 syncache 264 4 0 4 1 1 0 1 0 8 0 tcpqe 32 306 0 306 1 1 0 1 0 8 0 tcpcb 544 65 0 61 1 0 1 1 0 8 0 inpcb 280 451 0 443 3 0 3 3 0 8 2 nd6 48 6 0 4 1 0 1 1 0 8 0 ppxss 1128 3 0 3 1 0 1 1 0 8 1 pffrag 232 77 0 77 1 0 1 1 0 482 1 pffrnode 88 77 0 77 1 0 1 1 0 8 1 pffrent 40 154 0 154 1 0 1 1 0 8 1 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 34 0 2 1 0 1 1 0 8 0 pfstkey 112 34 0 2 1 0 1 1 0 8 0 pfstate 328 34 0 2 3 0 3 3 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 256 278 0 82 14 0 14 14 0 8 1 art_table 32 279 0 82 2 0 2 2 0 8 0 art_node 16 52 0 18 1 0 1 1 0 8 0 sysvmsgpl 40 89 0 56 1 0 1 1 0 8 0 semupl 112 3 0 3 1 0 1 1 0 8 1 semapl 112 11 0 2 1 0 1 1 0 8 0 shmpl 112 13 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino1pl 128 1629 0 222 46 0 46 46 0 8 0 ffsino 272 1629 0 222 95 0 95 95 0 8 0 nchpl 144 2060 0 440 61 0 61 61 0 8 0 uvmvnodes 72 1777 0 0 33 0 33 33 0 8 0 vnodes 208 1777 0 0 94 0 94 94 0 8 0 namei 1024 5711 0 5709 1 0 1 1 0 8 0 percpumem 16 30 0 0 1 0 1 1 0 8 0 scxspl 192 5584 0 5584 8 4 4 7 0 8 4 plimitpl 152 19 0 11 1 0 1 1 0 8 0 sigapl 432 353 0 337 3 1 2 3 0 8 0 futexpl 56 3570 0 3569 1 0 1 1 0 8 0 knotepl 112 70 0 51 1 0 1 1 0 8 0 kqueuepl 104 49 0 47 1 0 1 1 0 8 0 pipelkpl 48 115 0 105 1 0 1 1 0 8 0 pipepl 120 230 0 211 2 1 1 2 0 8 0 fdescpl 496 354 0 337 3 0 3 3 0 8 0 filepl 152 2615 0 2512 7 1 6 7 0 8 2 lockfpl 104 30 0 27 1 0 1 1 0 8 0 lockfspl 48 13 0 11 1 0 1 1 0 8 0 sessionpl 112 18 0 7 1 0 1 1 0 8 0 pgrppl 48 22 0 11 1 0 1 1 0 8 0 ucredpl 96 301 0 292 1 0 1 1 0 8 0 zombiepl 144 337 0 337 1 0 1 1 0 8 1 processpl 896 370 0 337 4 0 4 4 0 8 0 procpl 632 673 0 628 5 0 5 5 0 8 0 srpgc 64 2 0 2 1 0 1 1 0 8 1 sosppl 128 3 0 3 1 0 1 1 0 8 1 sockpl 400 604 0 584 6 1 5 5 0 8 3 mcl64k 65536 6 0 0 1 0 1 1 0 8 0 mcl16k 16384 1 0 0 1 0 1 1 0 8 0 mcl12k 12288 3 0 0 1 0 1 1 0 8 0 mcl9k 9216 1 0 0 1 0 1 1 0 8 0 mcl8k 8192 4 0 0 1 0 1 1 0 8 0 mcl4k 4096 6 0 0 1 0 1 1 0 8 0 mcl2k2 2112 1 0 0 1 0 1 1 0 8 0 mcl2k 2048 168 0 0 20 0 20 20 0 8 0 mtagpl 80 18 0 0 1 0 1 1 0 8 0 mbufpl 256 209 0 0 14 1 13 13 0 8 0 bufpl 280 6555 0 1341 373 0 373 373 0 8 0 anonpl 16 50281 0 33758 72 1 71 71 0 125 4 amapchunkpl 152 1837 0 1656 8 0 8 8 0 158 0 amappl16 192 1603 0 743 49 1 48 48 0 8 5 amappl15 184 182 0 174 1 0 1 1 0 8 0 amappl14 176 90 0 85 1 0 1 1 0 8 0 amappl12 160 9 0 9 2 2 0 1 0 8 0 amappl11 152 54 0 39 1 0 1 1 0 8 0 amappl10 144 15 0 8 1 0 1 1 0 8 0 amappl9 136 603 0 599 1 0 1 1 0 8 0 amappl8 128 129 0 105 1 0 1 1 0 8 0 amappl7 120 104 0 93 1 0 1 1 0 8 0 amappl6 112 54 0 50 1 0 1 1 0 8 0 amappl5 104 138 0 124 1 0 1 1 0 8 0 amappl4 96 606 0 575 1 0 1 1 0 8 0 amappl3 88 182 0 172 1 0 1 1 0 8 0 amappl2 80 2000 0 1915 3 1 2 3 0 8 0 amappl1 72 17656 0 17193 25 15 10 20 0 8 0 amappl 80 926 0 875 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 14 0 0 1 0 1 1 0 8 0 uaddrrnd 24 354 0 337 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 354 0 337 1 0 1 1 0 8 0 vmmpekpl 168 6766 0 6735 2 0 2 2 0 8 0 vmmpepl 168 50705 0 48558 121 10 111 114 0 357 17 vmsppl 368 353 0 337 2 0 2 2 0 8 0 pdppl 4096 715 0 674 6 0 6 6 0 8 0 pvpl 32 165188 0 144835 173 1 172 172 0 265 7 pmappl 232 353 0 337 2 1 1 2 0 8 0 extentpl 40 46 0 29 1 0 1 1 0 8 0 phpool 112 171 0 5 5 0 5 5 0 8 0