panic: m_zero: M_READONLY Stopped at db_enter+0xa: popq %rbp TID PID UID PRFLAGS PFLAGS CPU COMMAND 472585 93477 65534 0x10 0 1 syz-executor1 *105137 93477 65534 0x10 0x4000000 0K syz-executor1 db_enter() at db_enter+0xa sys/arch/amd64/amd64/db_interface.c:399 panic() at panic+0x147 sys/kern/subr_prf.c:208 m_free(ffffff006eea0500) at m_free+0x17a sys/kern/uipc_mbuf.c:1267 m_freem(ffffffff) at m_freem+0x2d sys/kern/uipc_mbuf.c:525 vio_txeof(ffff800000173000) at vio_txeof+0x104 sys/dev/pv/if_vio.c:1140 vio_start(0) at vio_start+0x3b sys/dev/pv/if_vio.c:723 if_qstart_compat(ffff800000173568) at if_qstart_compat+0x3b sys/net/if.c:679 ifq_serialize(ffff8000001734f0,0) at ifq_serialize+0x126 sys/net/ifq.c:100 if_enqueue(ffffff006a2bb100,ffff800000173290) at if_enqueue+0xd6 ifq_start sys/net/ifq.h:455 [inline] if_enqueue(ffffff006a2bb100,ffff800000173290) at if_enqueue+0xd6 sys/net/if.c:719 ether_output(ffffff006eea0300,ffff800000173290,ffffff006a2bb100,ffff800000025220) at ether_output+0xa4 sys/net/if_ethersubr.c:343 ip_output(ffffff006f2df7a8,ffffff006a2bb100,0,ffffff006eea0700,ffffff00679db808,ac08c4f79d980583) at ip_output+0xed8 sys/netinet/ip_output.c:511 udp_output(1400,ffffff00679db808,0,ffffff006eea0700) at udp_output+0x439 sys/netinet/udp_usrreq.c:1004 sosend(ffffff00750afe10,ffff800021165418,ffff8000211654c0,1000,0,ac08c4f79d980583) at sosend+0x467 sys/kern/uipc_socket.c:513 dofilewritev(ffff8000210a2720,ffff8000211654c0,1000,ffff8000211654d8,f3b149d6588) at dofilewritev+0x13b sys/kern/sys_generic.c:364 end trace frame: 0xffff800021165480, count: 0 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}> show panic m_zero: M_READONLY ddb{0}> trace db_enter() at db_enter+0xa sys/arch/amd64/amd64/db_interface.c:399 panic() at panic+0x147 sys/kern/subr_prf.c:208 m_free(ffffff006eea0500) at m_free+0x17a sys/kern/uipc_mbuf.c:1267 m_freem(ffffffff) at m_freem+0x2d sys/kern/uipc_mbuf.c:525 vio_txeof(ffff800000173000) at vio_txeof+0x104 sys/dev/pv/if_vio.c:1140 vio_start(0) at vio_start+0x3b sys/dev/pv/if_vio.c:723 if_qstart_compat(ffff800000173568) at if_qstart_compat+0x3b sys/net/if.c:679 ifq_serialize(ffff8000001734f0,0) at ifq_serialize+0x126 sys/net/ifq.c:100 if_enqueue(ffffff006a2bb100,ffff800000173290) at if_enqueue+0xd6 ifq_start sys/net/ifq.h:455 [inline] if_enqueue(ffffff006a2bb100,ffff800000173290) at if_enqueue+0xd6 sys/net/if.c:719 ether_output(ffffff006eea0300,ffff800000173290,ffffff006a2bb100,ffff800000025220) at ether_output+0xa4 sys/net/if_ethersubr.c:343 ip_output(ffffff006f2df7a8,ffffff006a2bb100,0,ffffff006eea0700,ffffff00679db808,ac08c4f79d980583) at ip_output+0xed8 sys/netinet/ip_output.c:511 udp_output(1400,ffffff00679db808,0,ffffff006eea0700) at udp_output+0x439 sys/netinet/udp_usrreq.c:1004 sosend(ffffff00750afe10,ffff800021165418,ffff8000211654c0,1000,0,ac08c4f79d980583) at sosend+0x467 sys/kern/uipc_socket.c:513 dofilewritev(ffff8000210a2720,ffff8000211654c0,1000,ffff8000211654d8,f3b149d6588) at dofilewritev+0x13b sys/kern/sys_generic.c:364 sys_write(40,ffff8000210a2720,0) at sys_write+0x6e sys/kern/sys_generic.c:283 syscall(0) at syscall+0x466 mi_syscall sys/sys/syscall_mi.h:99 [inline] syscall(0) at syscall+0x466 sys/arch/amd64/amd64/trap.c:583 Xsyscall(6,0,c,0,3,f38e4ba80d8) at Xsyscall+0x128 end of kernel end trace frame: 0xf3b149d6610, count: -17 ddb{0}> show registers rdi 0xffffffff81e323f0 kprintf_mutex rsi 0xffffffff811b5999 db_enter+0x9 rbp 0xffff800021164f10 rbx 0xffff800021164fb0 rdx 0xffff8000044de000 rcx 0xbf3 rax 0xffff8000044de000 r8 0xffff800021164ee0 r9 0 r10 0 r11 0xffffff006d458e70 r12 0x3000000008 r13 0xffff800021164f20 r14 0x100 r15 0xffffffff81bed177 apollo_pio_rec+0x6e0d rip 0xffffffff811b599a db_enter+0xa cs 0x8 rflags 0x206 rsp 0xffff800021164f10 ss 0x10 db_enter+0xa: popq %rbp ddb{0}> show proc PROC (syz-executor1) pid=105137 stat=onproc flags process=10 proc=4000000 pri=86, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff8000210a24c8,0xffff8000210a39f0 process=0xffff8000210b6668 user=0xffff800021160000, vmspace=0xffffff00659a6740 estcpu=36, cpticks=1, pctcpu=0.0 user=0, sys=1, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 93477 472585 19786 65534 7 0x10 syz-executor1 93477 520777 19786 65534 2 0x4000010 syz-executor1 *93477 105137 19786 65534 7 0x4000010 syz-executor1 93477 180587 19786 65534 3 0x4000090 fsleep syz-executor1 80188 523240 37994 65534 3 0x90 nanosleep syz-executor0 37994 285466 62319 0 3 0x82 wait syz-executor0 19786 180899 45671 65534 3 0x90 nanosleep syz-executor1 45671 489002 62319 0 3 0x82 wait syz-executor1 89746 146750 0 0 3 0x14200 bored sosplice 62319 396356 45648 0 3 0x82 thrsleep syz-fuzzer 62319 514383 45648 0 3 0x4000082 nanosleep syz-fuzzer 62319 89511 45648 0 3 0x4000082 thrsleep syz-fuzzer 62319 386980 45648 0 3 0x4000082 thrsleep syz-fuzzer 62319 123154 45648 0 3 0x4000082 thrsleep syz-fuzzer 62319 162672 45648 0 3 0x4000082 thrsleep syz-fuzzer 62319 363506 45648 0 3 0x4000082 kqread syz-fuzzer 62319 399863 45648 0 3 0x4000082 thrsleep syz-fuzzer 62319 400626 45648 0 3 0x4000082 thrsleep syz-fuzzer 62319 412229 45648 0 3 0x4000082 thrsleep syz-fuzzer 45648 340249 22339 0 3 0x10008a pause ksh 22339 342436 86120 0 3 0x92 select sshd 62087 311600 1 0 3 0x100083 ttyin getty 86120 419767 1 0 3 0x80 select sshd 49345 24053 16923 73 3 0x100090 kqread syslogd 16923 333455 1 0 3 0x100082 netio syslogd 71548 461304 1 77 3 0x100090 poll dhclient 47861 113961 1 0 3 0x80 poll dhclient 64186 94385 0 0 3 0x14200 pgzero zerothread 86257 515237 0 0 3 0x14200 aiodoned aiodoned 3662 95818 0 0 3 0x14200 syncer update 24773 60517 0 0 3 0x14200 cleaner cleaner 34784 23465 0 0 3 0x14200 reaper reaper 7176 129567 0 0 3 0x14200 pgdaemon pagedaemon 80434 217807 0 0 3 0x14200 bored crynlk 86597 343629 0 0 3 0x14200 bored crypto 91695 512620 0 0 3 0x40014200 acpi0 acpi0 2792 458639 0 0 3 0x40014200 idle1 49972 127119 0 0 3 0x14200 bored softnet 5613 158519 0 0 3 0x14200 bored systqmp 23208 312891 0 0 3 0x14200 bored systq 78735 113089 0 0 3 0x40014200 bored softclock 6430 376155 0 0 3 0x40014200 idle0 1 237145 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper