panic: pool_cache_item_magic_check: mbufpl cpu free list modified: item addr 0xfffffd8067d25a00+24 0x62cfa1d8dcb3fbed!=0x9d305c58bee7b1ed Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 326412 34167 0 0x1002 0x4002000 0 syz-fuzzer *346439 72220 0 0x12 0 1 sshd db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398 panic() at panic+0x15c sys/kern/subr_prf.c:207 pool_cache_get(ffffffff8264e7f0) at pool_cache_get+0x323 pool_cache_item_magic_check sys/kern/subr_pool.c:1789 [inline] pool_cache_get(ffffffff8264e7f0) at pool_cache_get+0x323 sys/kern/subr_pool.c:1892 pool_get() at pool_get+0x91 sys/kern/subr_pool.c:572 m_copym(fffffd806253ea00,1080,580,2) at m_copym+0x174 m_get sys/kern/uipc_mbuf.c:250 [inline] m_copym(fffffd806253ea00,1080,580,2) at m_copym+0x174 sys/kern/uipc_mbuf.c:667 tcp_output(ffff800000a7b540) at tcp_output+0x151c sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd806e97a788,9,fffffd806253ea00,0,0,ffff800020ac0ee0) at tcp_usrreq+0xa45 sosend(fffffd806e97a788,0,ffff800020aebd28,0,0,80) at sosend+0x645 sys/kern/uipc_socket.c:524 dofilewritev(ffff800020ac0ee0,4,ffff800020aebd28,0,ffff800020aebe10) at dofilewritev+0x1b7 sys/kern/sys_generic.c:364 sys_write(ffff800020ac0ee0,ffff800020aebdc0,ffff800020aebe10) at sys_write+0x83 sys/kern/sys_generic.c:284 syscall(ffff800020aebe90) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline] syscall(ffff800020aebe90) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555 Xsyscall(6,4,d55d0e1616b,4,4,d58c66dc340) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffdf230, count: 3 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{1}> ddb{1}> set $lines = 0 ddb{1}> set $maxwidth = 0 ddb{1}> show panic pool_cache_item_magic_check: mbufpl cpu free list modified: item addr 0xfffffd8067d25a00+24 0x62cfa1d8dcb3fbed!=0x9d305c58bee7b1ed ddb{1}> 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 pool_cache_get(ffffffff8264e7f0) at pool_cache_get+0x323 pool_cache_item_magic_check sys/kern/subr_pool.c:1789 [inline] pool_cache_get(ffffffff8264e7f0) at pool_cache_get+0x323 sys/kern/subr_pool.c:1892 pool_get() at pool_get+0x91 sys/kern/subr_pool.c:572 m_copym(fffffd806253ea00,1080,580,2) at m_copym+0x174 m_get sys/kern/uipc_mbuf.c:250 [inline] m_copym(fffffd806253ea00,1080,580,2) at m_copym+0x174 sys/kern/uipc_mbuf.c:667 tcp_output(ffff800000a7b540) at tcp_output+0x151c sys/netinet/tcp_output.c:673 tcp_usrreq(fffffd806e97a788,9,fffffd806253ea00,0,0,ffff800020ac0ee0) at tcp_usrreq+0xa45 sosend(fffffd806e97a788,0,ffff800020aebd28,0,0,80) at sosend+0x645 sys/kern/uipc_socket.c:524 dofilewritev(ffff800020ac0ee0,4,ffff800020aebd28,0,ffff800020aebe10) at dofilewritev+0x1b7 sys/kern/sys_generic.c:364 sys_write(ffff800020ac0ee0,ffff800020aebdc0,ffff800020aebe10) at sys_write+0x83 sys/kern/sys_generic.c:284 syscall(ffff800020aebe90) at syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline] syscall(ffff800020aebe90) at syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555 Xsyscall(6,4,d55d0e1616b,4,4,d58c66dc340) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffdf230, count: -12 ddb{1}> show registers rdi 0 rsi 0x1 rbp 0xffff800020aeb6d0 rbx 0xffff800020aeb780 rdx 0xffff800020ac0ee0 rcx 0 rax 0 r8 0xffffffff8182804f kprintf+0x16f r9 0x1 r10 0x25 r11 0xdd737bac48870236 r12 0x3000000008 r13 0xffff800020aeb6e0 r14 0x100 r15 0x1 rip 0xffffffff81d20338 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff800020aeb6c0 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb{1}> show proc PROC (sshd) pid=346439 stat=onproc flags process=12 proc=0 pri=51, usrpri=51, nice=20 forw=0xffffffffffffffff, list=0xffff800020ac0c68,0xffff800020ac13e0 process=0xffff800020a8bc10 user=0xffff800020ae6000, vmspace=0xfffffd806e7d82e8 estcpu=1, cpticks=2, pctcpu=0.4 user=0, sys=2, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 63665 331441 93160 0 2 0 syz-executor.0 63665 490723 93160 0 3 0x4000080 netcon2 syz-executor.0 93160 464917 34167 0 3 0x82 nanosleep syz-executor.0 20565 23551 0 0 3 0x14200 bored sosplice 2540 205479 34167 0 3 0x82 piperd syz-executor.1 34167 184784 91069 0 2 0x81082 syz-fuzzer 34167 451697 91069 0 2 0x4081082 syz-fuzzer 34167 360697 91069 0 2 0x4081082 syz-fuzzer 34167 91676 91069 0 2 0x4081082 syz-fuzzer 34167 5956 91069 0 2 0x4081082 syz-fuzzer 34167 503107 91069 0 2 0x4081082 syz-fuzzer 34167 181442 91069 0 2 0x4081082 syz-fuzzer 34167 326412 91069 0 7 0x4003002 syz-fuzzer 34167 267116 91069 0 2 0x4081082 syz-fuzzer 34167 422188 91069 0 2 0x4081082 syz-fuzzer 91069 411165 72220 0 3 0x10008a pause ksh *72220 346439 1778 0 7 0x12 sshd 55835 374770 1 0 3 0x100083 ttyin getty 1778 277537 1 0 3 0x80 select sshd 56503 377684 93089 74 3 0x100092 bpf pflogd 93089 52275 1 0 3 0x80 netio pflogd 45688 490139 93303 73 3 0x100090 kqread syslogd 93303 280476 1 0 3 0x100082 netio syslogd 42665 459021 1 77 3 0x100090 poll dhclient 75175 501969 1 0 3 0x80 poll dhclient 13197 391768 0 0 3 0x14200 pgzero zerothread 19484 381261 0 0 3 0x14200 aiodoned aiodoned 20032 340515 0 0 3 0x14200 syncer update 60103 388945 0 0 3 0x14200 cleaner cleaner 67529 44169 0 0 3 0x14200 reaper reaper 21065 143702 0 0 3 0x14200 pgdaemon pagedaemon 74463 176688 0 0 3 0x14200 bored crynlk 67985 307887 0 0 3 0x14200 bored crypto 3897 258643 0 0 3 0x40014200 acpi0 acpi0 21579 443966 0 0 3 0x40014200 idle1 78222 363671 0 0 2 0x14200 softnet 62275 423621 0 0 3 0x14200 bored systqmp 54660 59060 0 0 3 0x14200 bored systq 74882 331010 0 0 3 0x40014200 bored softclock 20954 520414 0 0 3 0x40014200 idle0 80000 481157 0 0 3 0x14200 bored smr 1 323925 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{1}> show all locks Process 72220 (sshd) thread 0xffff800020ac0ee0 (346439) exclusive rwlock netlock r = 0 (0xffffffff82505ce8) #0 witness_lock+0x52e sys/kern/subr_witness.c:1163 #1 solock+0x5a sys/kern/uipc_socket2.c:282 #2 sosend+0x51b sys/kern/uipc_socket.c:512 #3 dofilewritev+0x1b7 sys/kern/sys_generic.c:364 #4 sys_write+0x83 sys/kern/sys_generic.c:284 #5 syscall+0x4a4 mi_syscall sys/sys/syscall_mi.h:92 [inline] #5 syscall+0x4a4 sys/arch/amd64/amd64/trap.c:555 #6 Xsyscall+0x128 ddb{1}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim Kern Lim devbuf 9544 6422K 7648K 78643K 12329 0 0 pcb 13 8K 9K 78643K 135 0 0 rtable 92 8K 8K 78643K 456 0 0 ifaddr 66 14K 14K 78643K 146 0 0 counters 39 33K 33K 78643K 39 0 0 ioctlops 0 0K 4K 78643K 1484 0 0 iov 0 0K 16K 78643K 70 0 0 mount 1 1K 1K 78643K 1 0 0 vnodes 1227 77K 77K 78643K 1757 0 0 UFS quota 1 32K 32K 78643K 1 0 0 UFS mount 5 36K 36K 78643K 5 0 0 shm 2 1K 5K 78643K 12 0 0 VM map 5 2K 2K 78643K 6 0 0 sem 12 0K 0K 78643K 111 0 0 dirhash 12 2K 2K 78643K 12 0 0 ACPI 1808 196K 290K 78643K 12765 0 0 file desc 5 13K 25K 78643K 458 0 0 sigio 1 0K 0K 78643K 6 0 0 proc 61 63K 95K 78643K 507 0 0 subproc 32 2K 2K 78643K 51 0 0 NFS srvsock 1 0K 0K 78643K 1 0 0 NFS daemon 1 16K 16K 78643K 1 0 0 ip_moptions 0 0K 0K 78643K 40 0 0 in_multi 19 1K 2K 78643K 73 0 0 ether_multi 1 0K 0K 78643K 5 0 0 mrt 0 0K 0K 78643K 2 0 0 ISOFS mount 1 32K 32K 78643K 1 0 0 MSDOSFS mount 1 16K 16K 78643K 1 0 0 ttys 66 291K 291K 78643K 66 0 0 exec 0 0K 1K 78643K 276 0 0 pagedep 1 8K 8K 78643K 1 0 0 inodedep 1 32K 32K 78643K 1 0 0 newblk 1 0K 0K 78643K 1 0 0 VM swap 7 26K 26K 78643K 7 0 0 UVM amap 107 54K 63K 78643K 2520 0 0 UVM aobj 42 2K 2K 78643K 48 0 0 memdesc 1 4K 4K 78643K 1 0 0 crypto data 1 1K 1K 78643K 1 0 0 ip6_options 0 0K 1K 78643K 83 0 0 NDP 16 0K 0K 78643K 40 0 0 temp 192 3556K 3628K 78643K 12657 0 0 kqueue 0 0K 0K 78643K 3 0 0 SYN cache 2 16K 16K 78643K 2 0 0 ddb{1}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle arp 64 15 0 11 1 0 1 1 0 8 0 plcache 128 20 0 0 1 0 1 1 0 8 0 rtpcb 80 41 0 39 1 0 1 1 0 8 0 rtentry 112 81 0 48 2 0 2 2 0 8 0 unpcb 120 390 0 378 1 0 1 1 0 8 0 syncache 264 7 0 7 2 2 0 1 0 8 0 tcpqe 32 6193 0 6193 2 2 0 2 0 8 0 tcpcb 544 194 0 189 1 0 1 1 0 8 0 inpcb 280 1126 0 1117 3 0 3 3 0 8 2 rttmr 72 1 0 1 1 1 0 1 0 8 0 nd6 48 8 0 7 1 0 1 1 0 8 0 ppxss 1128 15 0 15 1 0 1 1 0 8 1 pffrag 232 10 0 10 1 1 0 1 0 482 0 pffrnode 88 10 0 10 1 1 0 1 0 8 0 pffrent 40 149 0 149 1 1 0 1 0 8 0 pfosfp 40 846 0 423 5 0 5 5 0 8 0 pfosfpen 112 1428 0 714 21 0 21 21 0 8 0 pfstitem 24 76 0 5 1 0 1 1 0 8 0 pfstkey 112 76 0 5 3 0 3 3 0 8 0 pfstate 328 76 0 5 6 0 6 6 0 8 0 pfrule 1360 21 0 16 2 1 1 2 0 8 0 art_heap8 4096 3 0 1 3 0 3 3 0 8 1 art_heap4 256 345 0 183 15 2 13 15 0 8 1 art_table 32 348 0 184 2 0 2 2 0 8 0 art_node 16 80 0 49 1 0 1 1 0 8 0 sysvmsgpl 40 15 0 8 1 0 1 1 0 8 0 semupl 112 2 0 2 1 1 0 1 0 8 0 semapl 112 107 0 97 1 0 1 1 0 8 0 shmpl 112 46 0 6 2 0 2 2 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino1pl 128 2138 0 734 46 0 46 46 0 8 0 ffsino 272 2138 0 734 96 1 95 95 0 8 0 nchpl 144 3013 0 1404 61 0 61 61 0 8 0 uvmvnodes 72 2584 0 0 47 0 47 47 0 8 0 vnodes 208 2584 0 0 136 0 136 136 0 8 0 namei 1024 9894 0 9894 2 1 1 1 0 8 1 percpumem 16 30 0 0 1 0 1 1 0 8 0 vcpupl 1984 3 0 0 1 0 1 1 0 8 0 vmpool 552 4 0 1 2 1 1 1 0 8 0 scxspl 192 9521 0 9521 11 10 1 7 0 8 1 plimitpl 152 52 0 44 1 0 1 1 0 8 0 sigapl 432 655 0 640 3 1 2 3 0 8 0 futexpl 56 11870 0 11870 1 0 1 1 0 8 1 knotepl 112 140 0 121 1 0 1 1 0 8 0 kqueuepl 104 130 0 128 1 0 1 1 0 8 0 pipepl 112 568 0 549 2 1 1 1 0 8 0 fdescpl 488 656 0 640 3 0 3 3 0 8 0 filepl 152 6087 0 5981 7 1 6 6 0 8 1 lockfpl 104 201 0 200 1 0 1 1 0 8 0 lockfspl 48 69 0 68 1 0 1 1 0 8 0 sessionpl 112 19 0 8 1 0 1 1 0 8 0 pgrppl 48 25 0 14 1 0 1 1 0 8 0 ucredpl 96 966 0 957 1 0 1 1 0 8 0 zombiepl 144 640 0 640 3 2 1 1 0 8 1 processpl 896 672 0 640 4 0 4 4 0 8 0 procpl 632 1706 0 1664 5 0 5 5 0 8 1 srpgc 64 2 0 2 1 1 0 1 0 8 0 sosppl 128 16 0 16 1 1 0 1 0 8 0 sockpl 384 1567 0 1544 7 1 6 6 0 8 3 mcl64k 65536 10 0 0 2 0 2 2 0 8 0 mcl16k 16384 6 0 0 1 0 1 1 0 8 0 mcl12k 12288 7 0 0 1 0 1 1 0 8 0 mcl9k 9216 2 0 0 1 0 1 1 0 8 0 mcl8k 8192 17 0 0 3 0 3 3 0 8 0 mcl4k 4096 12 0 0 2 0 2 2 0 8 0 mcl2k2 2112 2 0 0 1 0 1 1 0 8 0 mcl2k 2048 222 0 0 26 0 26 26 0 8 0 mtagpl 80 88 0 0 2 0 2 2 0 8 0 mbufpl 256 494 0 0 29 0 29 29 0 8 0 bufpl 256 7720 0 1317 401 0 401 401 0 8 0 anonpl 16 83841 0 66121 92 5 87 90 0 124 10 amapchunkpl 152 4273 0 4161 19 9 10 12 0 158 5 amappl16 192 3620 0 2596 68 8 60 64 0 8 8 amappl15 184 4 0 3 1 0 1 1 0 8 0 amappl14 176 33 0 31 2 1 1 1 0 8 0 amappl12 160 71 0 68 1 0 1 1 0 8 0 amappl11 152 206 0 190 1 0 1 1 0 8 0 amappl10 144 10 0 8 1 0 1 1 0 8 0 amappl9 136 632 0 626 1 0 1 1 0 8 0 amappl8 128 183 0 156 1 0 1 1 0 8 0 amappl7 120 45 0 39 1 0 1 1 0 8 0 amappl6 112 227 0 215 1 0 1 1 0 8 0 amappl5 104 209 0 193 1 0 1 1 0 8 0 amappl4 96 866 0 836 1 0 1 1 0 8 0 amappl3 88 197 0 191 1 0 1 1 0 8 0 amappl2 80 4315 0 4243 4 2 2 3 0 8 0 amappl1 72 24608 0 24162 26 16 10 20 0 8 0 amappl 80 1968 0 1928 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 17 0 17 1 1 0 1 0 8 0 aobjpl 64 47 0 6 1 0 1 1 0 8 0 uaddrrnd 24 660 0 640 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 660 0 640 1 0 1 1 0 8 0 vmmpekpl 168 9394 0 9357 2 0 2 2 0 8 0 vmmpepl 168 88339 0 86176 175 42 133 134 0 357 34 vmsppl 368 655 0 640 2 0 2 2 0 8 0 pdppl 4096 1327 0 1285 7 1 6 6 0 8 0 pvpl 32 259735 0 238841 225 19 206 209 0 265 25 pmappl 232 659 0 641 3 1 2 2 0 8 0 extentpl 40 41 0 26 1 0 1 1 0 8 0 phpool 112 597 0 8 17 0 17 17 0 8 0