panic: kernel diagnostic assertion "len >= 0 && !M_READONLY(m)" failed: file "/syzkaller/managers/main/kernel/sys/kern/uipc_mbuf.c", line 1384 Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND * 66460 37161 0 0 0x4000000 0 syz-executor.6 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:440 panic(ffffffff8254c243) at panic+0x161 sys/kern/subr_prf.c:202 __assert(ffffffff825bc0e6,ffffffff825cea0d,568,ffffffff8255f800) at __assert+0x25 sys/kern/subr_prf.c:161 m_align(fffffd8068c08e00,ffffffd3) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385 bpf_movein(ffff80002e7f3610,ffff800000d10200,ffff80002e7f3378,ffff80002e7f3278) at bpf_movein+0x25e sys/net/bpf.c:228 bpfwrite(31700,ffff80002e7f3610,5) at bpfwrite+0x128 sys/net/bpf.c:648 spec_write(ffff80002e7f3470) at spec_write+0xcb sys/kern/spec_vnops.c:309 VOP_WRITE(fffffd807c254a50,ffff80002e7f3610,5,fffffd807f7d8960) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245 vn_write(fffffd806a1fe1e0,ffff80002e7f3610,1) at vn_write+0x19c sys/kern/vfs_vnops.c:414 dofilewritev(ffff80002169a548,3,ffff80002e7f3610,1,ffff80002e7f3710) at dofilewritev+0x19c sys/kern/sys_generic.c:381 sys_pad_pwrite(ffff80002169a548,ffff80002e7f36b8,ffff80002e7f3710) at sys_pad_pwrite+0x92 sys_pwrite sys/kern/vfs_syscalls.c:3354 [inline] sys_pad_pwrite(ffff80002169a548,ffff80002e7f36b8,ffff80002e7f3710) at sys_pad_pwrite+0x92 sys/kern/vfs_syscalls.c:3426 syscall(ffff80002e7f3780) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x6cc4c4175b0, count: 2 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 *cpu0: kernel diagnostic assertion "len >= 0 && !M_READONLY(m)" failed: file "/syzkaller/managers/main/kernel/sys/kern/uipc_mbuf.c", line 1384 ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:440 panic(ffffffff8254c243) at panic+0x161 sys/kern/subr_prf.c:202 __assert(ffffffff825bc0e6,ffffffff825cea0d,568,ffffffff8255f800) at __assert+0x25 sys/kern/subr_prf.c:161 m_align(fffffd8068c08e00,ffffffd3) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385 bpf_movein(ffff80002e7f3610,ffff800000d10200,ffff80002e7f3378,ffff80002e7f3278) at bpf_movein+0x25e sys/net/bpf.c:228 bpfwrite(31700,ffff80002e7f3610,5) at bpfwrite+0x128 sys/net/bpf.c:648 spec_write(ffff80002e7f3470) at spec_write+0xcb sys/kern/spec_vnops.c:309 VOP_WRITE(fffffd807c254a50,ffff80002e7f3610,5,fffffd807f7d8960) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245 vn_write(fffffd806a1fe1e0,ffff80002e7f3610,1) at vn_write+0x19c sys/kern/vfs_vnops.c:414 dofilewritev(ffff80002169a548,3,ffff80002e7f3610,1,ffff80002e7f3710) at dofilewritev+0x19c sys/kern/sys_generic.c:381 sys_pad_pwrite(ffff80002169a548,ffff80002e7f36b8,ffff80002e7f3710) at sys_pad_pwrite+0x92 sys_pwrite sys/kern/vfs_syscalls.c:3354 [inline] sys_pad_pwrite(ffff80002169a548,ffff80002e7f36b8,ffff80002e7f3710) at sys_pad_pwrite+0x92 sys/kern/vfs_syscalls.c:3426 syscall(ffff80002e7f3780) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x6cc4c4175b0, count: -13 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff80002e7f30a0 rbx 0x18 rdx 0xffff800000c0a780 rcx 0 rax 0xffff80002169a548 r8 0 r9 0x8080808080808080 r10 0x1ca265e49dbf18ca r11 0x1993b662cf01fd19 r12 0 r13 0xffffffd3 r14 0 r15 0x1 rip 0xffffffff811d4e78 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff80002e7f3090 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (syz-executor.6) pid=66460 stat=onproc flags process=0 proc=4000000 pri=32, usrpri=82, nice=20 forw=0xffffffffffffffff, list=0xffff80002169b268,0xffff80002169a7f8 process=0xffff8000ffffbb60 user=0xffff80002e7ee000, vmspace=0xfffffd8074abf010 estcpu=36, cpticks=1, pctcpu=0.0 user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 7813 169375 54831 0 2 0 syz-executor.0 46240 501804 48917 0 2 0 syz-executor.7 46240 294585 48917 0 3 0x4000080 fsleep syz-executor.7 37161 495376 70622 0 2 0 syz-executor.6 *37161 66460 70622 0 7 0x4000000 syz-executor.6 40291 515700 97802 0 2 0 syz-executor.5 40291 361825 97802 0 3 0x4000080 fsleep syz-executor.5 76073 81905 49502 0 2 0 syz-executor.1 76073 296870 49502 0 3 0x4000080 fsleep syz-executor.1 82621 130662 34123 0 3 0x80 nanoslp syz-executor.3 82621 381942 34123 0 2 0x4000000 syz-executor.3 82621 93832 34123 0 3 0x4000080 fsleep syz-executor.3 49502 358672 14680 0 2 0x482 syz-executor.1 70622 133694 14680 0 3 0x82 nanoslp syz-executor.6 48917 253804 14680 0 3 0x82 nanoslp syz-executor.7 95058 470581 1 0 3 0x100083 ttyin getty 25420 499469 0 0 3 0x14200 acct acct 34123 246989 14680 0 3 0x82 nanoslp syz-executor.3 97802 332974 14680 0 3 0x82 nanoslp syz-executor.5 22559 142330 14680 0 2 0x2 syz-executor.4 39228 13491 14680 0 2 0x482 syz-executor.2 24018 194412 0 0 3 0x14200 bored sosplice 54831 138306 14680 0 3 0x82 nanoslp syz-executor.0 14680 31092 65057 0 3 0x82 thrsleep syz-fuzzer 14680 295582 65057 0 2 0x4000002 syz-fuzzer 14680 343574 65057 0 3 0x4000082 thrsleep syz-fuzzer 14680 448055 65057 0 3 0x4000082 thrsleep syz-fuzzer 14680 38014 65057 0 3 0x4000082 thrsleep syz-fuzzer 14680 332258 65057 0 3 0x4000082 kqread syz-fuzzer 14680 495627 65057 0 3 0x4000082 thrsleep syz-fuzzer 14680 284589 65057 0 3 0x4000082 thrsleep syz-fuzzer 14680 482162 65057 0 3 0x4000082 thrsleep syz-fuzzer 65057 126555 4352 0 3 0x10008a sigsusp ksh 4352 420052 76688 0 3 0x9a kqread sshd 76688 157803 1 0 3 0x88 kqread sshd 71341 83111 51255 73 3 0x100090 kqread syslogd 51255 411219 1 0 3 0x100082 netio syslogd 27419 226394 1 0 3 0x100080 kqread resolvd 42097 343897 18210 77 3 0x100092 kqread dhcpleased 19978 507932 18210 77 3 0x100092 kqread dhcpleased 18210 69904 1 0 3 0x80 kqread dhcpleased 78330 401200 0 0 3 0x14200 bored smr 54251 190188 0 0 2 0x14200 zerothread 11072 97487 0 0 3 0x14200 aiodoned aiodoned 50435 27013 0 0 3 0x14200 syncer update 51664 500847 0 0 3 0x14200 cleaner cleaner 92631 155518 0 0 3 0x14200 reaper reaper 59620 225289 0 0 3 0x14200 pgdaemon pagedaemon 86486 153152 0 0 3 0x14200 bored viomb 19623 439894 0 0 3 0x40014200 acpi0 acpi0 26207 488207 0 0 3 0x14200 bored softnet 27528 175939 0 0 3 0x14200 bored systqmp 93478 58545 0 0 3 0x14200 bored systq 8403 72058 0 0 2 0x40014200 softclock 15751 464984 0 0 3 0x40014200 idle0 1 230619 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 10210 6491K 7282K 78643K 15141 0 pcb 13 20K 24K 78643K 640 0 rtable 217 8K 10K 78643K 1102 0 ifaddr 90 18K 19K 78643K 609 0 sysctl 2 0K 0K 78643K 4 0 counters 27 17K 17K 78643K 60 0 ioctlops 0 0K 4K 78643K 424 0 iov 0 0K 20K 78643K 426 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 4 0 vnodes 1339 84K 84K 78643K 3026 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 5K 78643K 25 0 VM map 2 0K 0K 78643K 2 0 sem 12 0K 0K 78643K 522 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12548 0 file desc 16 57K 73K 78643K 4020 0 sigio 0 0K 0K 78643K 10 0 proc 59 55K 71K 78643K 896 0 subproc 104 6K 6K 78643K 273 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 0 0K 0K 78643K 119 0 in_multi 88 5K 6K 78643K 379 0 ether_multi 1 0K 0K 78643K 58 0 mrt 1 0K 0K 78643K 4 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 241 1076K 1076K 78643K 241 0 exec 0 0K 2K 78643K 1316 0 tdb 3 0K 0K 78643K 3 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 367 346K 364K 78643K 50008 0 UVM aobj 48 6K 6K 78643K 54 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 183 0 NDP 13 0K 2K 78643K 88 0 temp 133 4695K 4765K 78643K 26271 0 kqueue 12 18K 24K 78643K 197 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 rtpcb 120 158 0 155 2 1 1 2 0 8 0 rtentry 112 277 0 185 4 1 3 4 0 8 0 unpcb 136 2066 0 2053 27 24 3 6 0 8 2 syncache 296 13 0 13 4 4 0 1 0 8 0 tcpqe 32 93 0 93 1 1 0 1 0 8 0 tcpcb 736 2620 0 2616 47 45 2 20 0 8 1 arp 88 45 0 28 1 0 1 1 0 8 0 inpcb 304 13940 0 13927 119 112 7 27 0 8 4 ip6q 72 37 0 37 3 3 0 1 0 8 0 ip6af 40 74 0 74 3 3 0 1 0 8 0 nd6 48 76 0 54 1 0 1 1 0 8 0 pkpcb 40 4 0 4 1 1 0 1 0 8 0 kcovpl 48 21 0 13 1 0 1 1 0 8 0 ppxss 1152 7 0 7 2 2 0 1 0 8 0 pfstscr 40 3 0 2 1 0 1 1 0 8 0 pfosfp 40 3 0 2 1 0 1 1 0 8 0 pfosfpen 112 3 0 2 1 0 1 1 0 8 0 pfrktable 1344 74 0 72 2 1 1 1 0 8 0 pftag 88 1 0 0 1 0 1 1 0 8 0 pfstitem 24 2 0 0 1 0 1 1 0 8 0 pfstkey 112 6 0 4 1 0 1 1 0 8 0 pfstate 320 3 0 2 1 0 1 1 0 8 0 pfrule 1360 148 0 137 2 0 2 2 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 1306 0 954 32 9 23 30 0 8 0 art_table 32 1307 0 954 4 0 4 4 0 8 0 art_node 16 276 0 196 1 0 1 1 0 8 0 sysvmsgpl 40 39 0 12 1 0 1 1 0 8 0 semupl 112 3 0 3 1 1 0 1 0 8 0 semapl 112 518 0 508 1 0 1 1 0 8 0 shmpl 112 51 0 6 2 0 2 2 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 6915 0 5471 91 0 91 91 0 8 0 ffsino 240 6915 0 5471 86 0 86 86 0 8 0 nchpl 144 12388 0 10763 62 0 62 62 0 8 0 uvmvnodes 80 5926 0 0 121 0 121 121 0 8 0 vnodes 224 5926 0 0 349 0 349 349 0 8 0 namei 1024 39998 0 39997 3 2 1 2 0 8 0 vcpupl 1984 21 0 0 3 0 3 3 0 8 0 vmpool 528 42 0 21 4 2 2 2 0 8 0 pfiaddrpl 120 26 0 26 3 3 0 1 0 8 0 scxspl 216 38028 0 38028 17 14 3 8 0 8 3 plimitpl 152 501 0 487 1 0 1 1 0 8 0 sigapl 424 4281 0 4239 6 1 5 6 0 8 0 futexpl 64 40588 0 40584 1 0 1 1 0 8 0 knotepl 120 39648 0 39568 11 1 10 10 0 8 7 kqueuepl 184 1057 0 1049 23 19 4 7 0 8 3 pipepl 304 564 0 536 15 12 3 8 0 8 0 fdescpl 432 4266 0 4239 4 0 4 4 0 8 0 filepl 120 34910 0 34666 57 45 12 18 0 8 3 lockfpl 104 3475 0 3471 12 10 2 3 0 8 1 lockfspl 48 1104 0 1100 1 0 1 1 0 8 0 sessionpl 144 37 0 21 1 0 1 1 0 8 0 pgrppl 48 46 0 30 1 0 1 1 0 8 0 ucredpl 96 2824 0 2813 1 0 1 1 0 8 0 zombiepl 144 4239 0 4238 1 0 1 1 0 8 0 processpl 1000 4281 0 4238 6 0 6 6 0 8 0 procpl 672 10346 0 10289 10 4 6 7 0 8 0 sosppl 168 832 0 831 2 1 1 1 0 8 0 sockpl 448 16168 0 16142 244 233 11 40 0 8 8 mcl64k 65536 198 0 198 6 5 1 1 0 8 1 mcl16k 16384 430 0 430 2 1 1 1 0 8 1 mcl12k 12288 183 0 183 6 5 1 1 0 8 1 mcl9k 9216 88 0 88 7 6 1 1 0 8 1 mcl8k 8192 248 0 248 6 5 1 1 0 8 1 mcl4k 4096 315 0 315 6 5 1 1 0 8 1 mcl2k2 2112 17 0 17 10 9 1 1 0 8 1 mcl2k 2048 85847 0 85801 31 24 7 16 0 8 0 mtagpl 96 512 0 494 8 6 2 7 0 8 0 mbufpl 256 176228 0 176012 308 286 22 294 0 8 0 bufpl 288 12531 0 6122 458 0 458 458 0 8 0 anonpl 24 1096821 0 1080621 133 13 120 122 0 188 0 amapchunkpl 152 142301 0 141544 78 39 39 47 0 158 7 amappl16 200 9423 0 8784 42 7 35 36 0 8 1 amappl15 192 1095 0 1090 1 0 1 1 0 8 0 amappl14 184 45 0 43 1 0 1 1 0 8 0 amappl13 176 703 0 700 1 0 1 1 0 8 0 amappl12 168 247 0 243 2 1 1 1 0 8 0 amappl11 160 105 0 93 1 0 1 1 0 8 0 amappl10 152 687 0 681 1 0 1 1 0 8 0 amappl9 144 1201 0 1195 1 0 1 1 0 8 0 amappl8 136 1400 0 1319 3 0 3 3 0 8 0 amappl7 128 703 0 687 1 0 1 1 0 8 0 amappl6 120 961 0 935 2 1 1 2 0 8 0 amappl5 112 4343 0 4325 1 0 1 1 0 8 0 amappl4 104 1589 0 1556 2 0 2 2 0 8 0 amappl3 96 1144 0 1132 1 0 1 1 0 8 0 amappl2 88 1337 0 1290 3 1 2 3 0 8 0 amappl1 80 76819 0 76280 19 6 13 18 0 8 0 amappl 88 49256 0 49012 7 0 7 7 0 92 0 dma4096 4096 1 0 1 1 1 0 1 0 8 0 dma1024 1024 1 0 0 1 0 1 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 72 53 0 6 1 0 1 1 0 8 0 uaddrrnd 24 4308 0 4260 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 4308 0 4260 1 0 1 1 0 8 0 vmmpekpl 168 32155 0 32103 3 0 3 3 0 8 0 vmmpepl 168 387214 0 384684 191 60 131 131 0 357 13 vmsppl 272 4307 0 4260 6 2 4 4 0 8 0 rwobjpl 24 95418 0 87855 46 0 46 46 0 8 0 pdppl 4096 8622 0 8541 268 183 85 85 0 8 4 pvpl 32 1935021 0 1914850 298 102 196 259 0 265 8 pmappl 216 4307 0 4260 3 0 3 3 0 8 0 extentpl 40 58 0 38 1 0 1 1 0 8 0 phpool 112 1603 0 802 32 6 26 31 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:440 panic(ffffffff8254c243) at panic+0x161 sys/kern/subr_prf.c:202 __assert(ffffffff825bc0e6,ffffffff825cea0d,568,ffffffff8255f800) at __assert+0x25 sys/kern/subr_prf.c:161 m_align(fffffd8068c08e00,ffffffd3) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385 bpf_movein(ffff80002e7f3610,ffff800000d10200,ffff80002e7f3378,ffff80002e7f3278) at bpf_movein+0x25e sys/net/bpf.c:228 bpfwrite(31700,ffff80002e7f3610,5) at bpfwrite+0x128 sys/net/bpf.c:648 spec_write(ffff80002e7f3470) at spec_write+0xcb sys/kern/spec_vnops.c:309 VOP_WRITE(fffffd807c254a50,ffff80002e7f3610,5,fffffd807f7d8960) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245 vn_write(fffffd806a1fe1e0,ffff80002e7f3610,1) at vn_write+0x19c sys/kern/vfs_vnops.c:414 dofilewritev(ffff80002169a548,3,ffff80002e7f3610,1,ffff80002e7f3710) at dofilewritev+0x19c sys/kern/sys_generic.c:381 sys_pad_pwrite(ffff80002169a548,ffff80002e7f36b8,ffff80002e7f3710) at sys_pad_pwrite+0x92 sys_pwrite sys/kern/vfs_syscalls.c:3354 [inline] sys_pad_pwrite(ffff80002169a548,ffff80002e7f36b8,ffff80002e7f3710) at sys_pad_pwrite+0x92 sys/kern/vfs_syscalls.c:3426 syscall(ffff80002e7f3780) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x6cc4c4175b0, count: -13 ddb> machine ddbcpu 1 No such command ddb> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:440 panic(ffffffff8254c243) at panic+0x161 sys/kern/subr_prf.c:202 __assert(ffffffff825bc0e6,ffffffff825cea0d,568,ffffffff8255f800) at __assert+0x25 sys/kern/subr_prf.c:161 m_align(fffffd8068c08e00,ffffffd3) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385 bpf_movein(ffff80002e7f3610,ffff800000d10200,ffff80002e7f3378,ffff80002e7f3278) at bpf_movein+0x25e sys/net/bpf.c:228 bpfwrite(31700,ffff80002e7f3610,5) at bpfwrite+0x128 sys/net/bpf.c:648 spec_write(ffff80002e7f3470) at spec_write+0xcb sys/kern/spec_vnops.c:309 VOP_WRITE(fffffd807c254a50,ffff80002e7f3610,5,fffffd807f7d8960) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245 vn_write(fffffd806a1fe1e0,ffff80002e7f3610,1) at vn_write+0x19c sys/kern/vfs_vnops.c:414 dofilewritev(ffff80002169a548,3,ffff80002e7f3610,1,ffff80002e7f3710) at dofilewritev+0x19c sys/kern/sys_generic.c:381 sys_pad_pwrite(ffff80002169a548,ffff80002e7f36b8,ffff80002e7f3710) at sys_pad_pwrite+0x92 sys_pwrite sys/kern/vfs_syscalls.c:3354 [inline] sys_pad_pwrite(ffff80002169a548,ffff80002e7f36b8,ffff80002e7f3710) at sys_pad_pwrite+0x92 sys/kern/vfs_syscalls.c:3426 syscall(ffff80002e7f3780) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x6cc4c4175b0, count: -13