syzbot
malloc: free list modified: temp
Status:
upstream: reported on 2026/07/30 07:12
Reported-by: syzbot+271fd4fa6077bd7a1121@syzkaller.appspotmail.com
First crash: 21d, last: 21d
Sample crash report:
panic: Data modified on freelist: word 6 of object 0xffff800001615400 size 0x2d8 previous type temp (0x6a6af916 != 0xdeafbead)
Stopped at db_enter+0x25: addq $0x8,%rsp
TID PID UID PRFLAGS PFLAGS CPU COMMAND
335310 82338 0 0x2 0 1 syz-executor
*240947 11057 0 0x102004 0 0K sh
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff8347eaeb) at panic+0x1e5 sys/kern/subr_prf.c:198
malloc(2d8,7f,1) at malloc+0xdb6 sys/kern/kern_malloc.c:357
exec_elf_makecmds(ffff800031387a18,ffff80002a29de60) at exec_elf_makecmds+0x366 sys/kern/exec_elf.c:633
check_exec(ffff800031387a18,ffff80002a29de60) at check_exec+0x43d sys/kern/kern_exec.c:218
sys_execve(ffff800031387a18,ffff80002a29e320,ffff80002a29e270) at sys_execve+0x19b sys/kern/kern_exec.c:332
syscall(ffff80002a29e320) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a29e320) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x77427fde7230, 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{0}>
ddb{0}> set $lines = 0
ddb{0}> set $maxwidth = 0
ddb{0}> show panic
*cpu0: Data modified on freelist: word 6 of object 0xffff800001615400 size 0x2d8 previous type temp (0x6a6af916 != 0xdeafbead)
ddb{0}> show kasan
No such command
ddb{0}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff8347eaeb) at panic+0x1e5 sys/kern/subr_prf.c:198
malloc(2d8,7f,1) at malloc+0xdb6 sys/kern/kern_malloc.c:357
exec_elf_makecmds(ffff800031387a18,ffff80002a29de60) at exec_elf_makecmds+0x366 sys/kern/exec_elf.c:633
check_exec(ffff800031387a18,ffff80002a29de60) at check_exec+0x43d sys/kern/kern_exec.c:218
sys_execve(ffff800031387a18,ffff80002a29e320,ffff80002a29e270) at sys_execve+0x19b sys/kern/kern_exec.c:332
syscall(ffff80002a29e320) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a29e320) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x77427fde7230, count: -8
ddb{0}> show registers
rdi 0
rsi 0x1
rbp 0xffff80002a29d9e0
rbx 0xffffffff838f7e07 cpu_info_full_primary+0x2e07
rdx 0
rcx 0xffff800031387a18
rax 0xffffffff838f6ff0 cpu_info_full_primary+0x1ff0
r8 0x101010101010101
r9 0x8080808080808080
r10 0xd4941baf5a9574d9
r11 0xbf0f687e12828dcb
r12 0xffffffff838f7c08 cpu_info_full_primary+0x2c08
r13 0
r14 0
r15 0x1
rip 0xffffffff83265d25 db_enter+0x25
cs 0x8
rflags 0x246
rsp 0xffff80002a29d9d0
ss 0x10
db_enter+0x25: addq $0x8,%rsp
ddb{0}> show proc
PROC (sh) tid=240947 pid=11057 tcnt=1 stat=onproc
flags process=102004<INEXEC,SINGLEUNWIND,PLEDGE> proc=0
runpri=79, usrpri=86, slppri=32, nice=20
wchan=0x0, wmesg=, ps_single=0xffff800031387a18 scnt=0 ecnt=0
forw=0xffffffffffffffff, list=0xffff800031386fb8,0xffff800031387cc0
process=0xffff800045feb038 user=0xffff80002a299000, vmspace=0xfffff1006b1ae218
estcpu=36, cpticks=3, pctcpu=0.0, user=0, sys=3, intr=0
ddb{0}> ps
PID TID PPID UID S PRLAGS PFLAGS WAIT COMMAND
82338 335310 7028 0 7 0x2 0 syz-executor
*11057 240947 26849 0 7 0x102004 0 sh
26849 360669 8676 0 3 0x100002 0x88 sigsusp sh
36913 106321 32368 0 2 0x2 0 ifconfig
58111 454776 67646 0 2 0x100002 0 ndp
32368 235986 24646 0 3 0x100002 0x88 sigsusp sh
73886 1148 95038 32767 2 0x10 0 syz-executor
73886 276025 95038 32767 3 0x10 0x4000080 fsleep syz-executor
67646 310352 29706 0 3 0x100002 0x88 sigsusp sh
88648 420543 89776 32767 2 0x10 0 syz-executor
89776 445576 7028 0 3 0x2 0x80 wait syz-executor
24646 464664 48571 0 3 0 0x80 wait syz-executor
8676 320091 12784 0 3 0 0x80 wait syz-executor
29706 313673 46053 0 3 0 0x80 wait syz-executor
95038 203863 72981 32767 3 0x10 0x80 nanoslp syz-executor
48571 460350 7028 0 3 0x2 0x80 wait syz-executor
25882 418405 32609 32767 3 0x10 0x80 piperd syz-executor
46053 157460 7028 0 3 0x2 0x80 wait syz-executor
72981 54181 7028 0 3 0x2 0x80 wait syz-executor
12784 272164 7028 0 3 0x2 0x80 wait syz-executor
32609 404329 7028 0 3 0x2 0x80 wait syz-executor
7028 184577 39021 0 3 0x2 0x80 nanoslp syz-executor
39021 418553 49069 0 3 0x100002 0x88 sigsusp ksh
49069 419429 93592 0 3 0x10 0x88 kqread sshd-session
93592 370583 26571 0 3 0x12 0x80 kqread sshd-session
68277 273716 1 0 3 0x100003 0x80 ttyin getty
26571 279225 1 0 3 0 0x88 kqread sshd
66812 187425 30348 73 3 0x1100010 0x80 kqread syslogd
30348 92439 1 0 3 0x100002 0x80 sbwait syslogd
40309 231826 1 0 3 0x100000 0x80 kqread resolvd
14 10322 39908 77 3 0x100012 0x80 kqread dhcpleased
14247 410824 39908 77 3 0x100012 0x80 kqread dhcpleased
39908 178890 1 0 3 0 0x80 kqread dhcpleased
33230 425954 0 0 3 0x14000 0x200 bored smr
58115 34594 0 0 2 0x14000 0x200 zerothread
9418 195496 0 0 3 0x14000 0x200 aiodoned aiodoned
25189 82091 0 0 3 0x14000 0x200 syncer update
48137 127941 0 0 3 0x14000 0x200 cleaner cleaner
91462 436397 0 0 3 0x14000 0x200 reaper reaper
24122 489140 0 0 3 0x14000 0x200 pgdaemon pagedaemon
48479 172115 0 0 3 0x14000 0x200 bored viomb
50164 502231 0 0 3 0x14000 0x40000200 acpi0 acpi0
90606 41921 0 0 3 0x14000 0x40000200 idle1
93066 262559 0 0 3 0x14000 0x200 bored softnet1
78246 200328 0 0 3 0x14000 0x200 bored softnet0
93822 355082 0 0 3 0x14000 0x200 smrbar systqmp
3424 337823 0 0 3 0x14000 0x200 bored systq
45465 465571 0 0 3 0x14000 0x200 tmoslp softclockmp
17082 444756 0 0 3 0x14000 0x40000200 tmoslp softclock
23109 94195 0 0 3 0x14000 0x40000200 idle0
1 36812 0 0 3 0x2 0x80 wait init
0 0 -1 0 3 0x10000 0x200 scheduler swapper
ddb{0}> show all locks
CPU 0:
exclusive mutex /syzkaller/managers/setuid/kernel/sys/kern/kern_malloc.c:96 r = 0 (0xffffffff8391bd08)
#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+0x4b4 sys/kern/kern_lock.c:487
#2 malloc+0x2ef sys/kern/kern_malloc.c:200
#3 exec_elf_makecmds+0x366 sys/kern/exec_elf.c:633
#4 check_exec+0x43d sys/kern/kern_exec.c:218
#5 sys_execve+0x19b sys/kern/kern_exec.c:332
#6 syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#6 syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
#7 Xsyscall+0x128
Process 11057 (sh) thread 0xffff800031387a18 (240947)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff839e2bc0)
#0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1 syscall+0xaf4 mi_syscall sys/sys/syscall_mi.h:175 [inline]
#1 syscall+0xaf4 sys/arch/amd64/amd64/trap.c:783
#2 Xsyscall+0x128
exclusive mutex /syzkaller/managers/setuid/kernel/sys/kern/kern_malloc.c:96 r = 0 (0xffffffff8391bd08)
#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+0x4b4 sys/kern/kern_lock.c:487
#2 malloc+0x2ef sys/kern/kern_malloc.c:200
#3 exec_elf_makecmds+0x366 sys/kern/exec_elf.c:633
#4 check_exec+0x43d sys/kern/kern_exec.c:218
#5 sys_execve+0x19b sys/kern/kern_exec.c:332
#6 syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#6 syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
#7 Xsyscall+0x128
Process 93822 (systqmp) thread 0xffff800045ffe530 (355082)
shared rwlock systqmp r = 0 (0xffffffff83964e48)
#0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1 taskq_thread+0x12a sys/kern/kern_task.c:442
#2 proc_trampoline+0x10
ddb{0}> show malloc
Type InUse MemUse HighUse Limit Requests Type Lim
devbuf 11047 12014K 12034K 166960K 12162 0
pcb 17 12K 12K 166960K 17 0
rtable 163 4K 7K 166960K 501 0
pf 27 16K 16K 166960K 44 0
ifaddr 30 5K 7K 166960K 66 0
ifgroup 42 1K 2K 166960K 75 0
sysctl 1 1K 9K 166960K 5 0
counters 66 36K 37K 166960K 82 0
ioctlops 0 0K 4K 166960K 111 0
iov 0 0K 12K 166960K 9 0
mount 1 1K 1K 166960K 1 0
log 0 0K 0K 166960K 4 0
vnodes 1323 83K 83K 166960K 1643 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 12 0K 1K 166960K 22 0
dirhash 12 2K 2K 166960K 15 0
ACPI 1734 201K 291K 166960K 11964 0
file desc 22 78K 125K 166960K 479 0
sigio 0 0K 0K 166960K 6 0
proc 58 99K 196K 166960K 691 0
subproc 54 3K 6K 166960K 351 0
NFS srvsock 1 0K 0K 166960K 1 0
NFS daemon 1 16K 16K 166960K 1 0
ip_moptions 0 0K 0K 166960K 28 0
in_multi 57 4K 7K 166960K 154 0
ether_multi 1 0K 0K 166960K 3 0
mrt 0 0K 0K 166960K 9 0
ISOFS mount 1 32K 32K 166960K 1 0
MSDOSFS mount 1 16K 16K 166960K 1 0
ttys 79 360K 360K 166960K 79 0
exec 1 0K 1K 166960K 467 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 146K 197K 166960K 4886 0
UVM aobj 72 3K 3K 166960K 72 0
pinsyscall 44 88K 114K 166960K 1715 0
memdesc 1 4K 4K 166960K 1 0
crypto data 1 1K 1K 166960K 1 0
ip6_options 0 0K 0K 166960K 6 0
NDP 17 1K 2K 166960K 41 0
temp 58 9122K 9138K 166960K 5274 0
kqueue 13 20K 28K 166960K 53 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 28 0 0 1 0 1 1 0 8 0
rtpcb 120 49 0 45 1 0 1 1 0 8 0
rtentry 176 167 0 94 6 0 6 6 0 8 2
unpcb 144 133 0 118 2 0 2 2 0 8 1
syncache 336 8 0 8 1 0 1 1 0 8 1
tcpcb 736 176 0 172 7 0 7 7 0 8 6
arp 136 31 0 17 1 0 1 1 0 8 0
ipq 40 1 0 0 1 0 1 1 0 8 0
ipqe 40 2 0 1 1 0 1 1 0 8 0
inpcb 328 483 0 476 10 1 9 10 0 8 8
ip6q 72 1 0 0 1 0 1 1 0 8 0
ip6af 40 1 0 0 1 0 1 1 0 8 0
nd6 152 39 0 28 2 0 2 2 0 8 1
kcovpl 48 39 0 33 1 0 1 1 0 8 0
art_heap8 4096 1 0 0 1 0 1 1 0 8 0
art_heap4 256 663 0 376 30 6 24 30 0 8 6
art_table 40 664 0 376 5 0 5 5 0 8 1
art_node 32 167 0 99 1 0 1 1 0 8 0
sysvmsgpl 40 1 0 1 1 0 1 1 0 8 1
semapl 72 16 0 6 1 0 1 1 0 8 0
shmpl 112 69 0 0 2 0 2 2 0 8 0
dirhash 1024 19 0 2 3 0 3 3 0 8 0
dino2pl 256 1807 0 311 94 0 94 94 0 8 0
ffsino 296 1807 0 311 116 0 116 116 0 8 0
nchpl 144 2210 0 487 64 0 64 64 0 8 0
vnodes 216 2167 0 0 121 0 121 121 0 8 0
namei 1024 7478 0 7477 2 0 2 2 0 8 1
percpumem 16 57 0 8 1 0 1 1 0 8 0
kstatmem 264 37 0 16 2 0 2 2 0 8 0
scxspl 216 7542 0 7542 4 3 1 3 1 8 1
plimitpl 152 115 0 94 2 0 2 2 0 8 0
sigapl 424 710 0 660 7 0 7 7 0 8 0
knotepl 120 343 0 0 11 0 11 11 0 8 0
kqueuepl 224 62 0 53 1 0 1 1 0 8 0
pipepl 344 231 0 204 4 0 4 4 0 8 0
fdescpl 528 694 0 660 4 0 4 4 0 8 1
filepl 160 3083 0 2902 15 0 15 15 0 8 5
lockfpl 104 49 0 47 1 0 1 1 0 8 0
lockfspl 48 18 0 16 1 0 1 1 0 8 0
sessionpl 144 66 0 52 1 0 1 1 0 8 0
pgrppl 48 106 0 85 1 0 1 1 0 8 0
ucredpl 104 302 0 288 1 0 1 1 0 8 0
zombiepl 144 660 0 660 1 0 1 1 0 8 1
processpl 1232 710 0 660 5 0 5 5 0 8 0
procpl 664 967 0 916 6 0 6 6 0 8 1
sosppl 176 2 0 2 1 0 1 1 0 8 1
sockpl 752 669 0 643 15 4 11 15 0 8 8
mcl64k 65536 2 0 0 1 0 1 1 0 8 0
mcl8k 8192 2 0 0 1 0 1 1 0 8 0
mcl4k 4096 115 0 0 15 0 15 15 0 8 0
mcl2k 2048 17 0 0 3 0 3 3 0 8 0
mextrefs 64 17 0 0 1 0 1 1 0 8 0
mtagpl 96 1 0 0 1 0 1 1 0 8 0
mbufpl 256 1212 0 0 76 0 76 76 0 8 0
bufpl 272 2564 0 102 165 0 165 165 0 8 0
anonpl 32 7376 0 0 60 0 60 60 0 247 0
amapchunkpl 152 14290 0 13931 43 0 43 43 0 158 27
amappl16 200 1929 0 1921 15 6 9 14 0 8 8
amappl15 192 2 0 2 1 1 0 1 0 8 0
amappl14 184 470 0 465 1 0 1 1 0 8 0
amappl13 176 160 0 149 1 0 1 1 0 8 0
amappl12 168 944 0 916 2 0 2 2 0 8 0
amappl11 160 5 0 5 2 2 0 1 0 8 0
amappl10 152 61 0 51 1 0 1 1 0 8 0
amappl9 144 270 0 270 1 1 0 1 0 8 0
amappl8 136 115 0 114 1 0 1 1 0 8 0
amappl7 128 162 0 150 1 0 1 1 0 8 0
amappl6 120 203 0 198 1 0 1 1 0 8 0
amappl5 112 98 0 90 1 0 1 1 0 8 0
amappl4 104 290 0 273 1 0 1 1 0 8 0
amappl3 96 2730 0 2643 5 1 4 4 0 8 1
amappl2 88 577 0 523 2 0 2 2 0 8 0
amappl1 80 12591 0 12021 18 0 18 18 0 8 2
amappl 88 4061 0 3931 5 0 5 5 0 92 0
uvmvnodes 80 101 0 0 3 0 3 3 0 8 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 71 0 0 2 0 2 2 0 8 0
uaddrrnd 24 694 0 660 1 0 1 1 0 8 0
uaddrbest 32 2 0 0 1 0 1 1 0 8 0
uaddr 24 694 0 660 1 0 1 1 0 8 0
vmmpekpl 168 8188 0 8138 3 0 3 3 0 8 0
vmmpepl 168 53877 0 52145 113 0 113 113 0 357 30
vmsppl 488 693 0 660 7 1 6 6 0 8 0
rwobjpl 80 18084 0 17101 26 0 26 26 0 8 3
pdppl 4096 1395 0 1320 133 42 91 97 0 8 16
pvpl 32 13436 0 0 109 0 109 109 0 265 0
pmappl 256 693 0 660 4 1 3 3 0 8 0
extentpl 40 46 0 28 1 0 1 1 0 8 0
phpool 112 539 0 51 15 0 15 15 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(ffffffff8347eaeb) at panic+0x1e5 sys/kern/subr_prf.c:198
malloc(2d8,7f,1) at malloc+0xdb6 sys/kern/kern_malloc.c:357
exec_elf_makecmds(ffff800031387a18,ffff80002a29de60) at exec_elf_makecmds+0x366 sys/kern/exec_elf.c:633
check_exec(ffff800031387a18,ffff80002a29de60) at check_exec+0x43d sys/kern/kern_exec.c:218
sys_execve(ffff800031387a18,ffff80002a29e320,ffff80002a29e270) at sys_execve+0x19b sys/kern/kern_exec.c:332
syscall(ffff80002a29e320) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a29e320) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x77427fde7230, count: -8
ddb{0}> machine ddbcpu 1
Stopped at x86_ipi_db+0x27: addq $0x8,%rsp
x86_ipi_db(ffff80002999dff0) 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
__mp_lock(ffffffff839e23c0) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:142 [inline]
__mp_lock(ffffffff839e23c0) at __mp_lock+0x192 sys/kern/kern_lock.c:173
syscall(ffff80002a3522e0) at syscall+0xaf4 mi_syscall sys/sys/syscall_mi.h:175 [inline]
syscall(ffff80002a3522e0) at syscall+0xaf4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7b46777276e0, count: 9
ddb{1}> trace
x86_ipi_db(ffff80002999dff0) 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
__mp_lock(ffffffff839e23c0) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:142 [inline]
__mp_lock(ffffffff839e23c0) at __mp_lock+0x192 sys/kern/kern_lock.c:173
syscall(ffff80002a3522e0) at syscall+0xaf4 mi_syscall sys/sys/syscall_mi.h:175 [inline]
syscall(ffff80002a3522e0) at syscall+0xaf4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7b46777276e0, count: -6
Struck through repros no longer work on HEAD.