login: panic: Data modified on freelist: word 5 of object 0xffff8000006a0300 size 0x100 previous type devbuf (0xd != 0xdeadbeef) Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *517431 73207 0 0 0x4000000 0 syz-executor.0 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic() at panic+0x15c sys/kern/subr_prf.c:207 malloc(100,2,a) at malloc+0xa23 sys/kern/kern_malloc.c:331 bpfopen(21700,1,2000,ffff8000ffff8ed8) at bpfopen+0xb5 sys/net/bpf.c:360 spec_open_clone(ffff800014926478) at spec_open_clone+0x241 sys/kern/spec_vnops.c:737 spec_open(ffff800014926478) at spec_open+0x40e VOP_OPEN(fffffd8036cdb750,1,fffffd803f7c6c00,ffff8000ffff8ed8) at VOP_OPEN+0x6a sys/kern/vfs_vops.c:154 vn_open(ffff8000149266c8,1,0) at vn_open+0x4eb sys/kern/vfs_vnops.c:186 doopenat(ffff8000ffff8ed8,ffffff9c,20000040,0,0,ffff8000149268c0) at doopenat+0x28b sys/kern/vfs_syscalls.c:1157 syscall(ffff800014926940) at syscall+0x507 sys/arch/amd64/amd64/trap.c:555 Xsyscall(6,0,ffffffffffffffa2,0,4,c37754ec010) at Xsyscall+0x128 end of kernel end trace frame: 0xc399d215c30, count: 4 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 5 of object 0xffff8000006a0300 size 0x100 previous type devbuf (0xd != 0xdeadbeef) ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic() at panic+0x15c sys/kern/subr_prf.c:207 malloc(100,2,a) at malloc+0xa23 sys/kern/kern_malloc.c:331 bpfopen(21700,1,2000,ffff8000ffff8ed8) at bpfopen+0xb5 sys/net/bpf.c:360 spec_open_clone(ffff800014926478) at spec_open_clone+0x241 sys/kern/spec_vnops.c:737 spec_open(ffff800014926478) at spec_open+0x40e VOP_OPEN(fffffd8036cdb750,1,fffffd803f7c6c00,ffff8000ffff8ed8) at VOP_OPEN+0x6a sys/kern/vfs_vops.c:154 vn_open(ffff8000149266c8,1,0) at vn_open+0x4eb sys/kern/vfs_vnops.c:186 doopenat(ffff8000ffff8ed8,ffffff9c,20000040,0,0,ffff8000149268c0) at doopenat+0x28b sys/kern/vfs_syscalls.c:1157 syscall(ffff800014926940) at syscall+0x507 sys/arch/amd64/amd64/trap.c:555 Xsyscall(6,0,ffffffffffffffa2,0,4,c37754ec010) at Xsyscall+0x128 end of kernel end trace frame: 0xc399d215c30, count: -11 ddb>