panic: m_copym0: short mbuf chain Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *130405 56081 0 0x12 0 0 sshd db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic(ffffffff821cb38a) at panic+0x15c sys/kern/subr_prf.c:207 m_copym(fffffd806b7ed500,53c,39c,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff8000009f5760) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805dabf328,9,fffffd806b7ed400,0,0,ffff80001d7a7760) at tcp_usrreq+0xa54 sosend(fffffd805dabf328,0,ffff80001d7aeb28,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:549 dofilewritev(ffff80001d7a7760,4,ffff80001d7aeb28,0,ffff80001d7aec10) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d7a7760,ffff80001d7aebc0,ffff80001d7aec10) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d7aec90) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffe7130, 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(ffffffff821cb38a) at panic+0x15c sys/kern/subr_prf.c:207 m_copym(fffffd806b7ed500,53c,39c,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff8000009f5760) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805dabf328,9,fffffd806b7ed400,0,0,ffff80001d7a7760) at tcp_usrreq+0xa54 sosend(fffffd805dabf328,0,ffff80001d7aeb28,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:549 dofilewritev(ffff80001d7a7760,4,ffff80001d7aeb28,0,ffff80001d7aec10) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d7a7760,ffff80001d7aebc0,ffff80001d7aec10) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d7aec90) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffe7130, count: -10 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80001d7ae5f0 rbx 0xffff80001d7ae6a0 rdx 0x2 rcx 0 rax 0x1 r8 0xffffffff814d294f kprintf+0x15f r9 0x1 r10 0x2 r11 0x33e3aec6b7fc8e78 r12 0x3000000008 r13 0xffff80001d7ae600 r14 0x100 r15 0x1 rip 0xffffffff8138da68 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff80001d7ae5e0 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (sshd) pid=130405 stat=onproc flags process=12 proc=0 pri=24, usrpri=50, nice=20 forw=0xffffffffffffffff, list=0xffff80001d7a74f0,0xffff80001d7a7020 process=0xffff8000ffff8ae0 user=0xffff80001d7a9000, 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 38599 214594 92551 0 2 0 syz-executor.1 38599 90468 92551 0 2 0x4000000 syz-executor.1 1435 511096 1 0 3 0x82 nanosleep getty 45726 294908 0 0 3 0x14200 bored sosplice 92551 210691 28246 0 3 0x82 nanosleep syz-executor.1 93108 452741 28246 0 2 0x2 syz-executor.0 28246 70284 49518 0 3 0x82 thrsleep syz-fuzzer 28246 245276 49518 0 3 0x4000082 nanosleep syz-fuzzer 28246 196808 49518 0 3 0x4000082 thrsleep syz-fuzzer 28246 397106 49518 0 3 0x4000082 thrsleep syz-fuzzer 28246 131061 49518 0 3 0x4000082 thrsleep syz-fuzzer 28246 135389 49518 0 2 0x4000002 syz-fuzzer 28246 515840 49518 0 3 0x4000082 thrsleep syz-fuzzer 28246 407728 49518 0 3 0x4000082 thrsleep syz-fuzzer 49518 231605 56081 0 3 0x10008a pause ksh *56081 130405 91175 0 7 0x12 sshd 91175 413775 1 0 3 0x80 select sshd 44723 361533 4266 73 3 0x100090 kqread syslogd 4266 241624 1 0 3 0x100082 netio syslogd 27183 104155 1 77 3 0x100090 poll dhclient 56171 407070 1 0 3 0x80 poll dhclient 5210 176866 0 0 3 0x14200 bored smr 91863 385792 0 0 2 0x14200 zerothread 45834 218789 0 0 3 0x14200 aiodoned aiodoned 35965 415815 0 0 3 0x14200 syncer update 28753 249818 0 0 3 0x14200 cleaner cleaner 97914 6378 0 0 3 0x14200 reaper reaper 99864 510684 0 0 3 0x14200 pgdaemon pagedaemon 30815 87408 0 0 3 0x14200 bored crynlk 45672 142360 0 0 3 0x14200 bored crypto 84598 409456 0 0 3 0x40014200 acpi0 acpi0 75698 30954 0 0 3 0x14200 bored softnet 48926 217388 0 0 3 0x14200 bored systqmp 96613 411045 0 0 3 0x14200 bored systq 95281 485568 0 0 3 0x40014200 bored softclock 8980 455773 0 0 3 0x40014200 idle0 1 223234 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 9525 6352K 6613K 78643K 11655 0 pcb 13 22K 30K 78643K 218 0 rtable 100 3K 3K 78643K 514 0 ifaddr 97 19K 19K 78643K 258 0 counters 21 16K 16K 78643K 47 0 ioctlops 0 0K 2K 78643K 48 0 iov 0 0K 16K 78643K 387 0 mount 1 1K 1K 78643K 1 0 vnodes 1229 77K 78K 78643K 1794 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 5K 78643K 8 0 VM map 2 0K 0K 78643K 2 0 sem 12 1K 1K 78643K 16 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1809 195K 288K 78643K 12938 0 file desc 5 13K 25K 78643K 877 0 sigio 0 0K 0K 78643K 16 0 proc 50 38K 55K 78643K 501 0 subproc 32 2K 2K 78643K 34 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 0 0K 0K 78643K 68 0 in_multi 87 3K 4K 78643K 200 0 ether_multi 1 0K 0K 78643K 31 0 mrt 0 0K 0K 78643K 14 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 49 228K 228K 78643K 49 0 exec 0 0K 1K 78643K 298 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 150 137K 137K 78643K 2901 0 UVM aobj 28 2K 2K 78643K 30 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 165 0 NDP 16 0K 0K 78643K 51 0 temp 135 3040K 3104K 78643K 13992 0 kqueue 3 4K 12K 78643K 65 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 9 0 3 1 0 1 1 0 8 0 rtpcb 80 82 0 80 1 0 1 1 0 8 0 rtentry 112 88 0 48 2 0 2 2 0 8 0 unpcb 120 433 0 425 1 0 1 1 0 8 0 syncache 264 14 0 14 5 4 1 1 0 8 1 tcpqe 32 403 0 403 2 2 0 1 0 8 0 tcpcb 544 329 0 325 2 1 1 2 0 8 0 inpcb 280 1665 0 1126 41 2 39 39 0 8 0 rttmr 72 6 0 6 2 2 0 1 0 8 0 nd6 48 13 0 10 1 0 1 1 0 8 0 pkpcb 40 2 0 2 1 1 0 1 0 8 0 art_heap8 4096 2 0 0 2 0 2 2 0 8 0 art_heap4 256 385 0 192 15 1 14 14 0 8 0 art_table 32 387 0 192 2 0 2 2 0 8 0 art_node 16 87 0 49 1 0 1 1 0 8 0 sysvmsgpl 40 51 0 20 1 0 1 1 0 8 0 semupl 112 4 0 4 2 2 0 1 0 8 0 semapl 112 10 0 0 1 0 1 1 0 8 0 shmpl 112 28 0 2 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 2947 0 1553 88 0 88 88 0 8 0 ffsino 240 2947 0 1553 83 0 83 83 0 8 0 nchpl 144 4554 0 2960 60 0 60 60 0 8 0 uvmvnodes 72 3228 0 0 59 0 59 59 0 8 0 vnodes 208 3228 0 0 170 0 170 170 0 8 0 namei 1024 12304 0 12304 3 2 1 1 0 8 1 vcpupl 1984 14 0 0 2 0 2 2 0 8 0 vmpool 528 18 0 4 1 0 1 1 0 8 0 scxspl 192 12545 0 12545 2 1 1 1 0 8 1 plimitpl 152 78 0 71 1 0 1 1 0 8 0 sigapl 424 1067 0 1038 4 0 4 4 0 8 0 futexpl 56 17951 0 17951 3 2 1 1 0 8 1 knotepl 112 152 0 133 1 0 1 1 0 8 0 kqueuepl 144 167 0 163 1 0 1 1 0 8 0 pipelkpl 16 203 0 193 1 0 1 1 0 8 0 pipepl 120 406 0 387 2 0 2 2 0 8 1 fdescpl 432 1050 0 1036 2 0 2 2 0 8 0 filepl 120 6700 0 6606 4 0 4 4 0 8 1 lockfpl 104 232 0 231 1 0 1 1 0 8 0 lockfspl 48 86 0 85 1 0 1 1 0 8 0 sessionpl 112 17 0 8 1 0 1 1 0 8 0 pgrppl 48 25 0 16 1 0 1 1 0 8 0 ucredpl 96 732 0 725 1 0 1 1 0 8 0 zombiepl 144 1038 0 1038 1 0 1 1 0 8 1 processpl 920 1067 0 1038 4 0 4 4 0 8 0 procpl 624 2142 0 2105 5 1 4 4 0 8 0 sosppl 128 15 0 15 3 2 1 1 0 8 1 sockpl 400 2209 0 1662 58 2 56 56 0 8 1 mcl64k 65536 74 0 72 3 2 1 2 0 8 0 mcl16k 16384 6 0 6 3 2 1 1 0 8 1 mcl12k 12288 31 0 31 4 3 1 1 0 8 1 mcl9k 9216 13 0 13 3 2 1 1 0 8 1 mcl8k 8192 30 0 30 4 3 1 1 0 8 1 mcl4k 4096 71 0 71 5 4 1 1 0 8 1 mcl2k2 2112 11 0 11 4 3 1 1 0 8 1 mcl2k 2048 69713 0 69643 22 13 9 18 0 8 0 mtagpl 80 65 0 32 2 1 1 1 0 8 0 mbufpl 256 117009 0 116516 37 2 35 35 0 8 0 bufpl 280 5344 0 137 372 0 372 372 0 8 0 anonpl 16 107256 0 92058 92 25 67 77 0 107 4 amapchunkpl 152 5281 0 5145 29 16 13 20 0 158 7 amappl16 192 5108 0 4272 62 18 44 54 0 8 0 amappl15 184 1 0 0 1 0 1 1 0 8 0 amappl14 176 28 0 21 1 0 1 1 0 8 0 amappl13 168 1315 0 1308 1 0 1 1 0 8 0 amappl12 160 14 0 12 1 0 1 1 0 8 0 amappl11 152 50 0 40 1 0 1 1 0 8 0 amappl10 144 21 0 17 1 0 1 1 0 8 0 amappl9 136 371 0 370 1 0 1 1 0 8 0 amappl8 128 359 0 313 2 0 2 2 0 8 0 amappl7 120 107 0 95 1 0 1 1 0 8 0 amappl6 112 25 0 18 1 0 1 1 0 8 0 amappl5 104 562 0 550 1 0 1 1 0 8 0 amappl4 96 1272 0 1247 1 0 1 1 0 8 0 amappl3 88 593 0 587 1 0 1 1 0 8 0 amappl2 80 7593 0 7526 2 0 2 2 0 8 0 amappl1 72 27145 0 26740 24 15 9 17 0 8 0 amappl 80 2376 0 2329 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 29 0 2 1 0 1 1 0 8 0 uaddrrnd 24 1068 0 1040 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 1068 0 1040 1 0 1 1 0 8 0 vmmpekpl 168 10675 0 10645 2 0 2 2 0 8 0 vmmpepl 168 128293 0 126338 134 42 92 105 0 357 3 vmsppl 272 1067 0 1040 3 1 2 2 0 8 0 pdppl 4096 2142 0 2094 8 1 7 7 0 8 0 pvpl 32 314147 0 296711 203 41 162 177 0 265 16 pmappl 200 1067 0 1040 2 0 2 2 0 8 0 extentpl 40 53 0 36 1 0 1 1 0 8 0 phpool 112 346 0 37 9 0 9 9 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(ffffffff821cb38a) at panic+0x15c sys/kern/subr_prf.c:207 m_copym(fffffd806b7ed500,53c,39c,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff8000009f5760) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805dabf328,9,fffffd806b7ed400,0,0,ffff80001d7a7760) at tcp_usrreq+0xa54 sosend(fffffd805dabf328,0,ffff80001d7aeb28,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:549 dofilewritev(ffff80001d7a7760,4,ffff80001d7aeb28,0,ffff80001d7aec10) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d7a7760,ffff80001d7aebc0,ffff80001d7aec10) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d7aec90) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffe7130, 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(ffffffff821cb38a) at panic+0x15c sys/kern/subr_prf.c:207 m_copym(fffffd806b7ed500,53c,39c,2) at m_copym+0x553 sys/kern/uipc_mbuf.c:695 tcp_output(ffff8000009f5760) at tcp_output+0x154d sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd805dabf328,9,fffffd806b7ed400,0,0,ffff80001d7a7760) at tcp_usrreq+0xa54 sosend(fffffd805dabf328,0,ffff80001d7aeb28,0,0,80) at sosend+0x669 sys/kern/uipc_socket.c:549 dofilewritev(ffff80001d7a7760,4,ffff80001d7aeb28,0,ffff80001d7aec10) at dofilewritev+0x1ab sys/kern/sys_generic.c:365 sys_write(ffff80001d7a7760,ffff80001d7aebc0,ffff80001d7aec10) at sys_write+0x83 sys/kern/sys_generic.c:285 syscall(ffff80001d7aec90) at syscall+0x507 sys/arch/amd64/amd64/trap.c:570 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffe7130, count: -10