panic: m_copym0: short mbuf chain Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *215808 91465 0 0x12 0 0 sshd db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff821cb89c) at panic+0x15c sys/kern/subr_prf.c:207 m_copym(fffffd805985cd00,274,1ec,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff8000009f5320) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805dace198,9,fffffd805985cc00,0,0,ffff80001d7a8870) at tcp_usrreq+0xa54 sosend(fffffd805dace198,0,ffff80001d7785d8,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:549 dofilewritev(ffff80001d7a8870,4,ffff80001d7785d8,0,ffff80001d7786c0) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d7a8870,ffff80001d778670,ffff80001d7786c0) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d778740) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffea7b0, 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(ffffffff821cb89c) at panic+0x15c sys/kern/subr_prf.c:207 m_copym(fffffd805985cd00,274,1ec,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff8000009f5320) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805dace198,9,fffffd805985cc00,0,0,ffff80001d7a8870) at tcp_usrreq+0xa54 sosend(fffffd805dace198,0,ffff80001d7785d8,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:549 dofilewritev(ffff80001d7a8870,4,ffff80001d7785d8,0,ffff80001d7786c0) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d7a8870,ffff80001d778670,ffff80001d7786c0) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d778740) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffea7b0, count: -10 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80001d7780a0 rbx 0xffff80001d778150 rdx 0x2 rcx 0 rax 0x1 r8 0xffffffff81d602ef kprintf+0x15f r9 0x1 r10 0x2 r11 0xdc24cb3a4a682d02 r12 0x3000000008 r13 0xffff80001d7780b0 r14 0x100 r15 0x1 rip 0xffffffff82006a18 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff80001d778090 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (sshd) pid=215808 stat=onproc flags process=12 proc=0 pri=24, usrpri=50, nice=20 forw=0xffffffffffffffff, list=0xffff80001d7a8ae0,0xffff80001d7a8610 process=0xffff8000ffff83b0 user=0xffff80001d773000, vmspace=0xfffffd806bc0abb0 estcpu=0, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 76240 390178 20491 0 2 0x2 syz-executor.1 67914 114910 20491 0 2 0x2 syz-executor.0 20491 461220 79412 0 2 0x2 syz-fuzzer 20491 147686 79412 0 2 0x4000002 syz-fuzzer 20491 301685 79412 0 3 0x4000082 thrsleep syz-fuzzer 20491 39552 79412 0 3 0x4000082 thrsleep syz-fuzzer 20491 220611 79412 0 3 0x4000082 thrsleep syz-fuzzer 20491 177064 79412 0 3 0x4000082 thrsleep syz-fuzzer 20491 349876 79412 0 3 0x4000082 thrsleep syz-fuzzer 20491 189203 79412 0 3 0x4000082 thrsleep syz-fuzzer 79412 399143 91465 0 3 0x10008a pause ksh *91465 215808 87093 0 7 0x12 sshd 60391 22911 1 0 3 0x100083 ttyin getty 87093 367490 1 0 3 0x80 select sshd 91142 53942 18621 73 3 0x100090 kqread syslogd 18621 333767 1 0 3 0x100082 netio syslogd 17107 524279 1 77 3 0x100090 poll dhclient 1039 162192 1 0 3 0x80 poll dhclient 32185 265939 0 0 3 0x14200 bored smr 99332 500245 0 0 3 0x14200 pgzero zerothread 99203 391677 0 0 3 0x14200 aiodoned aiodoned 95725 404172 0 0 3 0x14200 syncer update 87591 421934 0 0 3 0x14200 cleaner cleaner 8213 275900 0 0 3 0x14200 reaper reaper 69766 453551 0 0 3 0x14200 pgdaemon pagedaemon 49241 203278 0 0 3 0x14200 bored crynlk 83272 110535 0 0 3 0x14200 bored crypto 82452 157780 0 0 3 0x40014200 acpi0 acpi0 70088 352789 0 0 3 0x14200 bored softnet 95319 502695 0 0 3 0x14200 bored systqmp 7117 160842 0 0 3 0x14200 bored systq 17879 247692 0 0 3 0x40014200 bored softclock 88576 468331 0 0 3 0x40014200 idle0 1 98853 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 9458 6327K 6456K 78643K 10587 0 pcb 13 8K 8K 78643K 13 0 rtable 105 3K 3K 78643K 193 0 ifaddr 44 10K 10K 78643K 50 0 counters 21 16K 16K 78643K 21 0 ioctlops 0 0K 2K 78643K 15 0 iov 0 0K 12K 78643K 1 0 mount 1 1K 1K 78643K 1 0 vnodes 1218 77K 77K 78643K 1231 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 5K 78643K 4 0 VM map 2 0K 0K 78643K 2 0 sem 4 0K 0K 78643K 4 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1809 195K 288K 78643K 12938 0 file desc 4 9K 25K 78643K 62 0 proc 48 38K 63K 78643K 361 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 186 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 122 23K 23K 78643K 1007 0 UVM aobj 14 2K 2K 78643K 14 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 NDP 6 0K 0K 78643K 10 0 temp 69 3028K 3092K 78643K 1834 0 kqueue 3 4K 6K 78643K 4 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 21 0 19 1 0 1 1 0 8 0 rtentry 112 45 0 1 2 0 2 2 0 8 0 unpcb 120 25 0 17 1 0 1 1 0 8 0 syncache 264 4 0 4 1 1 0 1 0 8 0 tcpqe 32 253 0 253 1 1 0 1 0 8 0 tcpcb 544 12 0 8 1 0 1 1 0 8 0 inpcb 280 42 0 35 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 256 189 0 0 12 0 12 12 0 8 0 art_table 32 190 0 0 2 0 2 2 0 8 0 art_node 16 44 0 4 1 0 1 1 0 8 0 sysvmsgpl 40 6 0 6 1 0 1 1 0 8 1 semapl 112 2 0 0 1 0 1 1 0 8 0 shmpl 112 12 0 0 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1459 0 61 88 0 88 88 0 8 0 ffsino 240 1459 0 61 83 0 83 83 0 8 0 nchpl 144 1736 0 133 60 0 60 60 0 8 0 uvmvnodes 72 1506 0 0 28 0 28 28 0 8 0 vnodes 208 1506 0 0 80 0 80 80 0 8 0 namei 1024 4300 0 4300 1 0 1 1 0 8 1 scxspl 192 4422 0 4422 1 0 1 1 0 8 1 plimitpl 152 16 0 9 1 0 1 1 0 8 0 sigapl 424 248 0 221 4 0 4 4 0 8 0 futexpl 56 604 0 604 1 0 1 1 0 8 1 knotepl 112 63 0 44 1 0 1 1 0 8 0 kqueuepl 144 4 0 2 1 0 1 1 0 8 0 pipelkpl 16 78 0 68 1 0 1 1 0 8 0 pipepl 120 156 0 137 1 0 1 1 0 8 0 fdescpl 432 234 0 221 2 0 2 2 0 8 0 filepl 120 1193 0 1098 4 0 4 4 0 8 1 lockfpl 104 14 0 13 1 0 1 1 0 8 0 lockfspl 48 6 0 5 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 81 1 0 1 1 0 8 0 zombiepl 144 221 0 221 1 0 1 1 0 8 1 processpl 920 248 0 221 4 0 4 4 0 8 0 procpl 624 293 0 259 4 0 4 4 0 8 1 sockpl 400 88 0 71 3 0 3 3 0 8 1 mcl64k 65536 257 0 257 32 0 32 32 0 8 32 mcl16k 16384 2 0 2 1 1 0 1 0 8 0 mcl8k 8192 4 0 4 1 0 1 1 0 8 1 mcl4k 4096 10 0 10 2 1 1 1 0 8 1 mcl2k 2048 70528 0 70471 21 9 12 18 0 8 4 mtagpl 80 4 0 2 2 1 1 1 0 8 0 mbufpl 256 112185 0 112089 24 6 18 22 0 8 8 bufpl 280 3245 0 125 223 0 223 223 0 8 0 anonpl 16 41678 0 28126 68 1 67 67 0 107 12 amapchunkpl 152 1231 0 1105 8 2 6 8 0 158 0 amappl16 192 1207 0 480 45 3 42 45 0 8 5 amappl15 184 9 0 7 1 0 1 1 0 8 0 amappl14 176 27 0 18 1 0 1 1 0 8 0 amappl13 168 28 0 24 1 0 1 1 0 8 0 amappl12 160 7 0 6 1 0 1 1 0 8 0 amappl11 152 45 0 36 1 0 1 1 0 8 0 amappl10 144 15 0 9 1 0 1 1 0 8 0 amappl9 136 376 0 374 1 0 1 1 0 8 0 amappl8 128 332 0 289 2 0 2 2 0 8 0 amappl7 120 114 0 102 1 0 1 1 0 8 0 amappl6 112 25 0 21 1 0 1 1 0 8 0 amappl5 104 185 0 175 1 0 1 1 0 8 0 amappl4 96 420 0 391 1 0 1 1 0 8 0 amappl3 88 102 0 96 1 0 1 1 0 8 0 amappl2 80 1052 0 997 2 0 2 2 0 8 0 amappl1 72 13839 0 13446 22 9 13 17 0 8 4 amappl 80 535 0 497 1 0 1 1 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 13 0 0 1 0 1 1 0 8 0 uaddrrnd 24 234 0 221 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 234 0 221 1 0 1 1 0 8 0 vmmpekpl 168 5848 0 5823 2 0 2 2 0 8 0 vmmpepl 168 35362 0 33658 105 6 99 102 0 357 19 vmsppl 272 233 0 221 2 1 1 2 0 8 0 pdppl 4096 474 0 442 6 1 5 6 0 8 0 pvpl 32 135520 0 119090 162 0 162 162 0 265 28 pmappl 200 233 0 221 1 0 1 1 0 8 0 extentpl 40 53 0 36 1 0 1 1 0 8 0 phpool 112 287 0 21 8 0 8 8 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(ffffffff821cb89c) at panic+0x15c sys/kern/subr_prf.c:207 m_copym(fffffd805985cd00,274,1ec,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff8000009f5320) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805dace198,9,fffffd805985cc00,0,0,ffff80001d7a8870) at tcp_usrreq+0xa54 sosend(fffffd805dace198,0,ffff80001d7785d8,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:549 dofilewritev(ffff80001d7a8870,4,ffff80001d7785d8,0,ffff80001d7786c0) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d7a8870,ffff80001d778670,ffff80001d7786c0) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d778740) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffea7b0, 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(ffffffff821cb89c) at panic+0x15c sys/kern/subr_prf.c:207 m_copym(fffffd805985cd00,274,1ec,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff8000009f5320) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805dace198,9,fffffd805985cc00,0,0,ffff80001d7a8870) at tcp_usrreq+0xa54 sosend(fffffd805dace198,0,ffff80001d7785d8,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:549 dofilewritev(ffff80001d7a8870,4,ffff80001d7785d8,0,ffff80001d7786c0) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d7a8870,ffff80001d778670,ffff80001d7786c0) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d778740) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffea7b0, count: -10