panic: Data modified on freelist: word 4 of object 0xffff80000148d340 size 0x30 previous type free (0x0 != 0xdeafbead) Stopped at db_enter+0x25: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 447971 99152 0 0 0 1 syz-executor *133099 34576 0 0x2 0 0 syz-executor db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83338fae) at panic+0x1e5 sys/kern/subr_prf.c:198 malloc(30,7f,9) at malloc+0xcf8 sys/kern/kern_malloc.c:353 dopselect(ffff80002a2b8a78,32,7716ff1ec760,0,0,ffff80002a2b79a0,e62153af80085998,ffff80002a2b7a40) at dopselect+0xe4 sys/kern/sys_generic.c:615 sys_pselect(ffff80002a2b8a78,ffff80002a2b7af0,ffff80002a2b7a40) at sys_pselect+0x25a sys/kern/sys_generic.c:589 syscall(ffff80002a2b7af0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80002a2b7af0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7716ff1ec710, count: 8 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: Data modified on freelist: word 4 of object 0xffff80000148d340 size 0x30 previous type free (0x0 != 0xdeafbead) ddb{0}> trace db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438 panic(ffffffff83338fae) at panic+0x1e5 sys/kern/subr_prf.c:198 malloc(30,7f,9) at malloc+0xcf8 sys/kern/kern_malloc.c:353 dopselect(ffff80002a2b8a78,32,7716ff1ec760,0,0,ffff80002a2b79a0,e62153af80085998,ffff80002a2b7a40) at dopselect+0xe4 sys/kern/sys_generic.c:615 sys_pselect(ffff80002a2b8a78,ffff80002a2b7af0,ffff80002a2b7a40) at sys_pselect+0x25a sys/kern/sys_generic.c:589 syscall(ffff80002a2b7af0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80002a2b7af0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7716ff1ec710, count: -7 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff80002a2b74d0 rbx 0xffffffff837fdddf cpu_info_full_primary+0x2ddf rdx 0 rcx 0xffff80002a2b8a78 rax 0xffffffff837fcff0 cpu_info_full_primary+0x1ff0 r8 0x101010101010101 r9 0x8080808080808080 r10 0x213a303777ed9806 r11 0x92001a29360ce984 r12 0xffffffff837fdbe0 cpu_info_full_primary+0x2be0 r13 0 r14 0 r15 0x1 rip 0xffffffff82fe3e75 db_enter+0x25 cs 0x8 rflags 0x246 rsp 0xffff80002a2b74c0 ss 0x10 db_enter+0x25: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor) tid=133099 pid=34576 tcnt=1 stat=onproc flags process=2 proc=0 runpri=52, usrpri=52, slppri=24, nice=20 wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0 forw=0xffffffffffffffff, list=0xffff80002a2b82b0,0xffff80002a2b94e8 process=0xffff80002a2c1878 user=0xffff80002a2b2000, vmspace=0xfffffd806e3df1f8 estcpu=2, cpticks=41, pctcpu=0.23, user=3, sys=37, intr=1 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 99152 447971 37657 0 7 0 syz-executor 80940 511444 18977 0 3 0x80 fsleep syz-executor 80940 89464 18977 0 2 0x4000000 syz-executor 3694 33935 4582 0 2 0 syz-executor 86430 339147 62033 0 2 0 syz-executor 86430 363779 62033 0 2 0x4000000 syz-executor 38058 274514 34576 0 2 0x2 syz-executor 62033 497993 34576 0 3 0x82 nanoslp syz-executor 37657 21866 34576 0 3 0x82 nanoslp syz-executor 18977 247920 34576 0 3 0x82 nanoslp syz-executor 4582 217609 34576 0 3 0x82 nanoslp syz-executor 2674 399336 34576 0 3 0x2 biowait syz-executor 57781 124284 34576 0 3 0x82 nanoslp syz-executor 88494 238931 34576 0 3 0x82 piperd syz-executor *34576 133099 91321 0 7 0x2 syz-executor 91321 183695 41075 0 3 0x10008a sigsusp ksh 41075 88777 64334 0 3 0x98 kqread sshd-session 64334 116838 99123 0 3 0x92 kqread sshd-session 46002 7530 1 0 3 0x100083 ttyin getty 99123 134121 1 0 3 0x88 kqread sshd 94964 481727 59558 74 3 0x1100092 bpf pflogd 59558 508767 1 0 3 0x80 sbwait pflogd 73089 468107 73922 73 3 0x1100090 kqread syslogd 73922 510165 1 0 3 0x100082 sbwait syslogd 77661 295312 1 0 3 0x100080 kqread resolvd 40737 42476 23904 77 3 0x100092 kqread dhcpleased 3928 87048 23904 77 3 0x100092 kqread dhcpleased 23904 503096 1 0 3 0x80 kqread dhcpleased 9613 408800 0 0 3 0x14200 bored smr 6075 303085 0 0 2 0x14200 zerothread 793 249384 0 0 3 0x14200 aiodoned aiodoned 67755 377860 0 0 3 0x14200 syncer update 64931 115285 0 0 3 0x14200 cleaner cleaner 43589 8003 0 0 2 0x14200 reaper 28179 500335 0 0 3 0x14200 pgdaemon pagedaemon 38326 10333 0 0 3 0x14200 bored viomb 2521 466270 0 0 3 0x40014200 acpi0 acpi0 67107 119757 0 0 3 0x40014200 idle1 2604 145442 0 0 3 0x14200 bored softnet7 22046 162868 0 0 3 0x14200 bored softnet6 49938 460022 0 0 3 0x14200 bored softnet5 19371 204316 0 0 3 0x14200 bored softnet4 70705 503607 0 0 3 0x14200 bored softnet3 39498 489097 0 0 3 0x14200 bored softnet2 64617 346533 0 0 3 0x14200 bored softnet1 41316 336085 0 0 3 0x14200 bored softnet0 63442 182364 0 0 3 0x14200 bored systqmp 81950 496230 0 0 3 0x14200 bored systq 94022 462695 0 0 3 0x14200 tmoslp softclockmp 26325 395991 0 0 3 0x40014200 tmoslp softclock 67680 465874 0 0 3 0x40014200 idle0 1 41422 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}> show all locks CPU 0: exclusive mutex /syzkaller/managers/multicore/kernel/sys/kern/kern_malloc.c:96 r = 0 (0xffffffff83863708) #0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline] #0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160 #1 mtx_enter_try+0x1ad sys/kern/kern_lock.c:311 #2 mtx_enter+0x62 sys/kern/kern_lock.c:261 #3 malloc+0x2f2 sys/kern/kern_malloc.c:199 #4 dopselect+0xe4 sys/kern/sys_generic.c:615 #5 sys_pselect+0x25a sys/kern/sys_generic.c:589 #6 syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] #6 syscall+0xbd4 sys/arch/amd64/amd64/trap.c:748 #7 Xsyscall+0x128 Process 99152 (syz-executor) thread 0xffff800033008d18 (447971) Process 2674 (syz-executor) thread 0xffff80002a2b9770 (399336) Process 43589 (reaper) thread 0xffff8000ffffc7d0 (8003) ddb{0}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10194 11023K 11023K 166960K 11274 0 pcb 17 12K 12K 166960K 18 0 rtable 225 7K 8K 166960K 295 0 pf 35 17K 18K 166960K 47 0 ifaddr 43 7K 7K 166960K 45 0 ifgroup 55 2K 2K 166960K 55 0 sysctl 4 1K 9K 166960K 12 0 counters 68 36K 36K 166960K 68 0 ioctlops 0 0K 4K 166960K 1484 0 iov 0 0K 16K 166960K 5 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1336 84K 84K 166960K 1361 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 5K 166960K 4 0 VM map 2 1K 1K 166960K 2 0 sem 5 0K 0K 166960K 5 0 dirhash 12 2K 2K 166960K 12 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 14 49K 89K 166960K 739 0 proc 71 115K 180K 166960K 537 0 subproc 72 4K 4K 166960K 72 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 3 0 in_multi 99 7K 7K 166960K 99 0 ether_multi 1 0K 0K 166960K 1 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 31 148K 148K 166960K 31 0 exec 0 0K 1K 166960K 371 0 fusefs mount 1 32K 32K 166960K 1 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 199 166K 177K 166960K 7433 0 UVM aobj 4 4K 4K 166960K 4 0 pinsyscall 39 78K 100K 166960K 1847 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 NDP 12 0K 2K 166960K 28 0 temp 35 8642K 8706K 166960K 6260 0 kqueue 13 20K 22K 166960K 23 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 40 0 37 1 0 1 1 0 8 0 rtentry 176 99 0 1 5 0 5 5 0 8 0 unpcb 144 34 0 17 1 0 1 1 0 8 0 syncache 336 3 0 3 1 1 0 1 0 8 0 tcpcb 736 9 0 5 1 0 1 1 0 8 0 arp 128 10 0 0 1 0 1 1 0 8 0 inpcb 328 74 0 67 1 0 1 1 0 8 0 nd6 144 19 0 0 1 0 1 1 0 8 0 pkpcb 40 1 0 1 1 0 1 1 0 8 1 kcovpl 48 8 0 0 1 0 1 1 0 8 0 pffrag 232 10 0 0 1 0 1 1 0 482 0 pffrnode 88 7 0 0 1 0 1 1 0 8 0 pffrent 40 14 0 3 1 0 1 1 0 8 0 pfosfp 40 1428 0 1005 5 0 5 5 0 8 0 pfosfpen 112 1428 0 714 21 0 21 21 0 8 0 pfstitem 24 47 0 1 1 0 1 1 0 8 0 pfstkey 128 47 0 1 2 0 2 2 0 8 0 pfstate 384 47 0 1 5 0 5 5 0 8 0 pfrule 1344 21 0 16 2 1 1 2 0 8 0 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 452 0 0 29 0 29 29 0 8 0 art_table 40 454 0 0 5 0 5 5 0 8 0 art_node 32 99 0 11 1 0 1 1 0 8 0 semapl 112 3 0 0 1 0 1 1 0 8 0 shmpl 112 1 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 2165 0 654 95 0 95 95 0 8 0 ffsino 296 2165 0 654 117 0 117 117 0 8 0 nchpl 144 2973 0 1292 63 0 63 63 0 8 0 uvmvnodes 80 2255 0 0 47 0 47 47 0 8 0 vnodes 216 2255 0 0 126 0 126 126 0 8 0 namei 1024 7813 0 7813 1 0 1 1 0 8 1 percpumem 16 49 0 0 1 0 1 1 0 8 0 kstatmem 264 26 0 0 2 0 2 2 0 8 0 scxspl 216 10034 0 10033 3 2 1 2 1 8 0 plimitpl 152 31 0 14 1 0 1 1 0 8 0 sigapl 424 1050 0 999 7 0 7 7 0 8 0 knotepl 120 61 0 0 2 0 2 2 0 8 0 kqueuepl 224 26 0 17 1 0 1 1 0 8 0 pipepl 344 107 0 80 3 0 3 3 0 8 0 fdescpl 528 1028 0 1000 3 0 3 3 0 8 0 filepl 160 2060 0 1852 9 0 9 9 0 8 0 lockfpl 104 10 0 8 1 0 1 1 0 8 0 lockfspl 48 6 0 4 1 0 1 1 0 8 0 sessionpl 144 22 0 13 1 0 1 1 0 8 0 pgrppl 48 31 0 14 1 0 1 1 0 8 0 ucredpl 104 76 0 63 1 0 1 1 0 8 0 zombiepl 144 1000 0 999 3 2 1 1 0 8 0 processpl 1248 1051 0 999 5 0 5 5 0 8 0 procpl 664 1658 0 1604 6 0 6 6 0 8 1 sockpl 752 150 0 123 4 1 3 4 0 8 0 mcl64k 65536 7 0 0 1 0 1 1 0 8 0 mcl16k 16384 5 0 0 1 0 1 1 0 8 0 mcl12k 12288 14 0 0 2 0 2 2 0 8 0 mcl9k 9216 4 0 0 1 0 1 1 0 8 0 mcl8k 8192 19 0 0 3 0 3 3 0 8 0 mcl4k 4096 116 0 0 15 0 15 15 0 8 0 mcl2k2 2112 1 0 0 1 0 1 1 0 8 0 mcl2k 2048 26 0 0 4 0 4 4 0 8 0 mtagpl 96 2 0 0 1 0 1 1 0 8 0 mbufpl 256 165 0 0 10 0 10 10 0 8 0 bufpl 280 3492 0 122 241 0 241 241 0 8 0 anonpl 32 5140 0 0 42 0 42 42 0 246 0 amapchunkpl 152 24056 0 23703 39 15 24 25 0 158 9 amappl16 200 1898 0 1880 5 3 2 5 0 8 0 amappl15 192 14 0 14 1 1 0 1 0 8 0 amappl14 184 126 0 114 1 0 1 1 0 8 0 amappl13 176 9 0 9 2 2 0 1 0 8 0 amappl12 168 1680 0 1652 3 1 2 2 0 8 0 amappl11 160 52 0 38 1 0 1 1 0 8 0 amappl10 152 19 0 19 1 1 0 1 0 8 0 amappl9 144 254 0 254 2 2 0 1 0 8 0 amappl8 136 37 0 35 1 0 1 1 0 8 0 amappl7 128 107 0 95 1 0 1 1 0 8 0 amappl6 120 175 0 172 1 0 1 1 0 8 0 amappl5 112 122 0 112 1 0 1 1 0 8 0 amappl4 104 295 0 275 1 0 1 1 0 8 0 amappl3 96 4978 0 4894 4 1 3 3 0 8 0 amappl2 88 634 0 575 2 0 2 2 0 8 0 amappl1 80 10680 0 10096 15 2 13 15 0 8 0 amappl 88 6695 0 6568 4 0 4 4 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 3 0 0 1 0 1 1 0 8 0 uaddrrnd 24 1028 0 1000 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 1028 0 1000 1 0 1 1 0 8 0 vmmpekpl 168 8438 0 8403 2 0 2 2 0 8 0 vmmpepl 168 65188 0 63442 95 9 86 87 0 357 4 vmsppl 488 1027 0 999 5 1 4 5 0 8 0 rwobjpl 80 19711 0 16592 64 0 64 64 0 8 0 pdppl 4096 2064 0 1998 110 38 72 84 0 8 6 pvpl 32 11598 0 0 95 1 94 94 0 265 0 pmappl 256 1027 0 999 3 1 2 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 282 0 42 8 0 8 8 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(ffffffff83338fae) at panic+0x1e5 sys/kern/subr_prf.c:198 malloc(30,7f,9) at malloc+0xcf8 sys/kern/kern_malloc.c:353 dopselect(ffff80002a2b8a78,32,7716ff1ec760,0,0,ffff80002a2b79a0,e62153af80085998,ffff80002a2b7a40) at dopselect+0xe4 sys/kern/sys_generic.c:615 sys_pselect(ffff80002a2b8a78,ffff80002a2b7af0,ffff80002a2b7a40) at sys_pselect+0x25a sys/kern/sys_generic.c:589 syscall(ffff80002a2b7af0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80002a2b7af0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:748 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7716ff1ec710, count: -7 ddb{0}> machine ddbcpu 1 Stopped at x86_ipi_db+0x27: addq $0x8,%rsp x86_ipi_db(ffff8000299edff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 mtx_enter(ffffffff838636f8) at mtx_enter+0xd2 sys/kern/kern_lock.c:264 malloc(20,62,2) at malloc+0x2f2 sys/kern/kern_malloc.c:199 amap_alloc1(40,2,0) at amap_alloc1+0x291 sys/uvm/uvm_amap.c:353 amap_copy(fffffd80720085d0,fffffd806abfb750,2,1,5e78c05b000,5e78c05b001) at amap_copy+0x24b sys/uvm/uvm_amap.c:-1 uvm_fault_check(ffff80003b8451f0,ffff80003b845228,ffff80003b845260,0) at uvm_fault_check+0x930 uvmfault_amapcopy sys/uvm/uvm_fault.c:249 [inline] uvm_fault_check(ffff80003b8451f0,ffff80003b845228,ffff80003b845260,0) at uvm_fault_check+0x930 sys/uvm/uvm_fault.c:784 uvm_fault(fffffd80720085d0,5e78c05b000,0,1) at uvm_fault+0x106 sys/uvm/uvm_fault.c:677 upageflttrap(ffff80003b845380,5e78c05bfa0) at upageflttrap+0xa9 sys/arch/amd64/amd64/trap.c:192 usertrap(ffff80003b845380) at usertrap+0x3c6 sys/arch/amd64/amd64/trap.c:605 recall_trap() at recall_trap+0x8 end of kernel end trace frame: 0x71a7ffb11790, count: 3 ddb{1}> trace x86_ipi_db(ffff8000299edff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 mtx_enter(ffffffff838636f8) at mtx_enter+0xd2 sys/kern/kern_lock.c:264 malloc(20,62,2) at malloc+0x2f2 sys/kern/kern_malloc.c:199 amap_alloc1(40,2,0) at amap_alloc1+0x291 sys/uvm/uvm_amap.c:353 amap_copy(fffffd80720085d0,fffffd806abfb750,2,1,5e78c05b000,5e78c05b001) at amap_copy+0x24b sys/uvm/uvm_amap.c:-1 uvm_fault_check(ffff80003b8451f0,ffff80003b845228,ffff80003b845260,0) at uvm_fault_check+0x930 uvmfault_amapcopy sys/uvm/uvm_fault.c:249 [inline] uvm_fault_check(ffff80003b8451f0,ffff80003b845228,ffff80003b845260,0) at uvm_fault_check+0x930 sys/uvm/uvm_fault.c:784 uvm_fault(fffffd80720085d0,5e78c05b000,0,1) at uvm_fault+0x106 sys/uvm/uvm_fault.c:677 upageflttrap(ffff80003b845380,5e78c05bfa0) at upageflttrap+0xa9 sys/arch/amd64/amd64/trap.c:192 usertrap(ffff80003b845380) at usertrap+0x3c6 sys/arch/amd64/amd64/trap.c:605 recall_trap() at recall_trap+0x8 end of kernel end trace frame: 0x71a7ffb11790, count: -12