panic: m_copym0: short mbuf chain Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *434664 16268 0 0x12 0 0 sshd db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff823cfca4) at panic+0x164 sys/kern/subr_prf.c:218 m_copym(fffffd806ac1c900,454,384,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff800000ac3760) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805da75008,9,fffffd806ac1c800,0,0,ffff80001d71c760) at tcp_usrreq+0xa54 sosend(fffffd805da75008,0,ffff80001d6cdaa8,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:555 dofilewritev(ffff80001d71c760,4,ffff80001d6cdaa8,0,ffff80001d6cdb90) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d71c760,ffff80001d6cdb40,ffff80001d6cdb90) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d6cdc10) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffed670, count: 5 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 m_copym0: short mbuf chain ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff823cfca4) at panic+0x164 sys/kern/subr_prf.c:218 m_copym(fffffd806ac1c900,454,384,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff800000ac3760) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805da75008,9,fffffd806ac1c800,0,0,ffff80001d71c760) at tcp_usrreq+0xa54 sosend(fffffd805da75008,0,ffff80001d6cdaa8,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:555 dofilewritev(ffff80001d71c760,4,ffff80001d6cdaa8,0,ffff80001d6cdb90) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d71c760,ffff80001d6cdb40,ffff80001d6cdb90) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d6cdc10) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffed670, count: -10 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80001d6cd570 rbx 0xffff80001d6cd620 rdx 0x2 rcx 0 rax 0x1 r8 0xffffffff82040b7f kprintf+0x15f r9 0x1 r10 0x2 r11 0x7661701cee90d9f5 r12 0x3000000008 r13 0xffff80001d6cd580 r14 0x100 r15 0x1 rip 0xffffffff8130eb58 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff80001d6cd560 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (sshd) pid=434664 stat=onproc flags process=12 proc=0 pri=24, usrpri=50, nice=20 forw=0xffffffffffffffff, list=0xffff80001d71d870,0xffff80001d71c290 process=0xffff80001d701238 user=0xffff80001d6c8000, vmspace=0xfffffd806bc0a770 estcpu=0, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 27524 83612 65396 60929 2 0x10 syz-executor.1 27524 149510 65396 60929 3 0x4000090 fsleep syz-executor.1 65396 300442 46604 0 3 0x82 nanosleep syz-executor.1 73522 224479 46604 0 2 0x2 syz-executor.0 46604 345155 34209 0 3 0x82 thrsleep syz-fuzzer 46604 30181 34209 0 3 0x4000082 nanosleep syz-fuzzer 46604 405569 34209 0 3 0x4000082 thrsleep syz-fuzzer 46604 297347 34209 0 3 0x4000082 thrsleep syz-fuzzer 46604 386699 34209 0 3 0x4000082 thrsleep syz-fuzzer 46604 407486 34209 0 2 0x4000002 syz-fuzzer 46604 81153 34209 0 3 0x4000082 thrsleep syz-fuzzer 34209 113835 16268 0 3 0x10008a pause ksh *16268 434664 61026 0 7 0x12 sshd 71179 505647 1 0 3 0x100083 ttyin getty 61026 367952 1 0 3 0x80 select sshd 4758 430843 10089 73 3 0x100090 kqread syslogd 10089 305838 1 0 3 0x100082 netio syslogd 239 335070 1 77 3 0x100090 poll dhclient 31079 30898 1 0 3 0x80 poll dhclient 41219 181116 0 0 3 0x14200 bored smr 83142 243957 0 0 2 0x14200 zerothread 52326 99228 0 0 3 0x14200 aiodoned aiodoned 305 166535 0 0 3 0x14200 syncer update 71677 377587 0 0 3 0x14200 cleaner cleaner 86304 183928 0 0 3 0x14200 reaper reaper 85989 218779 0 0 3 0x14200 pgdaemon pagedaemon 81220 373601 0 0 3 0x14200 bored crynlk 82541 62272 0 0 3 0x14200 bored crypto 61802 339514 0 0 3 0x40014200 acpi0 acpi0 30329 266091 0 0 3 0x14200 bored softnet 17002 415128 0 0 3 0x14200 bored systqmp 5919 27592 0 0 3 0x14200 bored systq 57528 358164 0 0 3 0x40014200 bored softclock 86592 340184 0 0 3 0x40014200 idle0 1 222461 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb> show all locks No such command ddb> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 9489 6841K 6841K 78643K 10622 0 pcb 13 8K 8K 78643K 13 0 rtable 105 3K 3K 78643K 189 0 ifaddr 39 10K 10K 78643K 41 0 sysctl 2 0K 0K 78643K 2 0 counters 21 16K 16K 78643K 21 0 ioctlops 0 0K 2K 78643K 15 0 iov 0 0K 2K 78643K 10 0 mount 1 1K 1K 78643K 1 0 vnodes 1222 77K 77K 78643K 1240 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 1K 78643K 2 0 VM map 2 0K 0K 78643K 2 0 sem 2 0K 0K 78643K 4 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1809 195K 288K 78643K 12938 0 file desc 5 13K 25K 78643K 53 0 proc 48 38K 54K 78643K 359 0 subproc 32 2K 2K 78643K 34 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 in_multi 33 2K 2K 78643K 33 0 ether_multi 1 0K 0K 78643K 1 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 37 175K 175K 78643K 37 0 exec 0 0K 1K 78643K 181 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 115 21K 22K 78643K 963 0 UVM aobj 3 2K 2K 78643K 3 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 2 0 NDP 9 0K 0K 78643K 9 0 temp 60 3847K 3911K 78643K 1865 0 kqueue 3 4K 9K 78643K 9 0 SYN cache 2 16K 16K 78643K 2 0 ddb> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle arp 64 6 0 0 1 0 1 1 0 8 0 rtpcb 80 19 0 17 1 0 1 1 0 8 0 rtentry 112 45 0 1 2 0 2 2 0 8 0 unpcb 120 23 0 15 1 0 1 1 0 8 0 syncache 264 4 0 4 1 1 0 1 0 8 0 tcpqe 32 69 0 69 1 0 1 1 0 8 1 tcpcb 544 18 0 10 1 0 1 1 0 8 0 inpcb 296 48 0 41 1 0 1 1 0 8 0 nd6 48 6 0 0 1 0 1 1 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 188 0 0 12 0 12 12 0 8 0 art_table 32 189 0 0 2 0 2 2 0 8 0 art_node 16 44 0 4 1 0 1 1 0 8 0 semapl 112 2 0 2 1 0 1 1 0 8 1 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1443 0 46 88 0 88 88 0 8 0 ffsino 240 1443 0 46 83 0 83 83 0 8 0 nchpl 144 1696 0 94 60 0 60 60 0 8 0 uvmvnodes 72 1502 0 0 28 0 28 28 0 8 0 vnodes 208 1502 0 0 80 0 80 80 0 8 0 namei 1024 4217 0 4216 1 0 1 1 0 8 0 scxspl 192 4692 0 4692 1 0 1 1 0 8 1 plimitpl 152 18 0 11 1 0 1 1 0 8 0 sigapl 424 239 0 211 4 0 4 4 0 8 0 futexpl 56 406 0 405 1 0 1 1 0 8 0 knotepl 112 66 0 46 1 0 1 1 0 8 0 kqueuepl 144 8 0 6 1 0 1 1 0 8 0 pipepl 272 75 0 64 1 0 1 1 0 8 0 fdescpl 432 225 0 211 2 0 2 2 0 8 0 filepl 120 1149 0 1052 4 0 4 4 0 8 1 lockfpl 104 5 0 4 1 0 1 1 0 8 0 lockfspl 48 3 0 2 1 0 1 1 0 8 0 sessionpl 112 17 0 7 1 0 1 1 0 8 0 pgrppl 48 17 0 7 1 0 1 1 0 8 0 ucredpl 96 88 0 80 1 0 1 1 0 8 0 zombiepl 144 211 0 211 1 0 1 1 0 8 1 processpl 928 239 0 211 4 0 4 4 0 8 0 procpl 624 265 0 230 3 0 3 3 0 8 0 sockpl 400 90 0 73 2 0 2 2 0 8 0 mcl9k 9216 1 0 1 1 0 1 1 0 8 1 mcl4k 4096 11 0 11 2 1 1 1 0 8 1 mcl2k2 2112 1 0 1 1 0 1 1 0 8 1 mcl2k 2048 91728 0 91679 17 3 14 14 0 8 7 mtagpl 96 15 0 2 2 1 1 1 0 8 0 mbufpl 256 144904 0 144771 11 2 9 9 0 8 0 bufpl 280 3254 0 125 224 0 224 224 0 8 0 anonpl 16 37974 0 22282 67 1 66 66 0 107 2 amapchunkpl 152 1049 0 870 9 0 9 9 0 158 1 amappl16 192 1017 0 201 43 0 43 43 0 8 2 amappl15 184 11 0 8 1 0 1 1 0 8 0 amappl14 176 24 0 18 1 0 1 1 0 8 0 amappl13 168 38 0 34 1 0 1 1 0 8 0 amappl12 160 11 0 10 2 1 1 1 0 8 0 amappl11 152 46 0 37 1 0 1 1 0 8 0 amappl10 144 21 0 15 1 0 1 1 0 8 0 amappl9 136 350 0 349 1 0 1 1 0 8 0 amappl8 128 290 0 265 1 0 1 1 0 8 0 amappl7 120 109 0 95 1 0 1 1 0 8 0 amappl6 112 19 0 17 1 0 1 1 0 8 0 amappl5 104 165 0 154 1 0 1 1 0 8 0 amappl4 96 426 0 396 1 0 1 1 0 8 0 amappl3 88 104 0 95 1 0 1 1 0 8 0 amappl2 80 970 0 902 2 0 2 2 0 8 0 amappl1 72 14067 0 13654 23 7 16 17 0 8 7 amappl 80 508 0 457 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 2 0 0 1 0 1 1 0 8 0 uaddrrnd 24 225 0 211 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 225 0 211 1 0 1 1 0 8 0 vmmpekpl 168 5696 0 5670 2 0 2 2 0 8 0 vmmpepl 168 35020 0 33110 115 5 110 110 0 357 26 vmsppl 272 224 0 211 2 0 2 2 0 8 1 pdppl 4096 456 0 422 6 0 6 6 0 8 1 pvpl 32 128845 0 110243 160 0 160 160 0 265 7 pmappl 200 224 0 211 1 0 1 1 0 8 0 extentpl 40 53 0 36 1 0 1 1 0 8 0 phpool 112 235 0 8 7 0 7 7 0 8 0 ddb> machine ddbcpu 0 No such command ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff823cfca4) at panic+0x164 sys/kern/subr_prf.c:218 m_copym(fffffd806ac1c900,454,384,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff800000ac3760) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805da75008,9,fffffd806ac1c800,0,0,ffff80001d71c760) at tcp_usrreq+0xa54 sosend(fffffd805da75008,0,ffff80001d6cdaa8,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:555 dofilewritev(ffff80001d71c760,4,ffff80001d6cdaa8,0,ffff80001d6cdb90) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d71c760,ffff80001d6cdb40,ffff80001d6cdb90) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d6cdc10) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffed670, count: -10 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff823cfca4) at panic+0x164 sys/kern/subr_prf.c:218 m_copym(fffffd806ac1c900,454,384,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff800000ac3760) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805da75008,9,fffffd806ac1c800,0,0,ffff80001d71c760) at tcp_usrreq+0xa54 sosend(fffffd805da75008,0,ffff80001d6cdaa8,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:555 dofilewritev(ffff80001d71c760,4,ffff80001d6cdaa8,0,ffff80001d6cdb90) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d71c760,ffff80001d6cdb40,ffff80001d6cdb90) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d6cdc10) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffed670, count: -10