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 *391647 98914 0 0 0x4000000 0 syz-executor.4 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:440 panic(ffffffff8254be5b) at panic+0x161 sys/kern/subr_prf.c:202 __assert(ffffffff825bbf89,ffffffff825cdd9d,568,ffffffff8255ec6a) at __assert+0x25 sys/kern/subr_prf.c:161 m_align(fffffd80684fe900,ffffffeb) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385 bpf_movein(ffff800027f335c8,ffff800000bf8800,ffff800027f33328,ffff800027f33228) at bpf_movein+0x25e sys/net/bpf.c:228 bpfwrite(41700,ffff800027f335c8,1) at bpfwrite+0x128 sys/net/bpf.c:648 spec_write(ffff800027f33420) at spec_write+0xcb sys/kern/spec_vnops.c:309 VOP_WRITE(fffffd8073332b08,ffff800027f335c8,1,fffffd807f7d8480) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245 vn_write(fffffd8067d9f978,ffff800027f335c8,0) at vn_write+0x152 sys/kern/vfs_vnops.c:414 dofilewritev(ffff80002161ea80,3,ffff800027f335c8,0,ffff800027f336c0) at dofilewritev+0x19c sys/kern/sys_generic.c:380 sys_write(ffff80002161ea80,ffff800027f33668,ffff800027f336c0) at sys_write+0x83 sys/kern/sys_generic.c:300 syscall(ffff800027f33730) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xa8b00ac8f10, 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(ffffffff8254be5b) at panic+0x161 sys/kern/subr_prf.c:202 __assert(ffffffff825bbf89,ffffffff825cdd9d,568,ffffffff8255ec6a) at __assert+0x25 sys/kern/subr_prf.c:161 m_align(fffffd80684fe900,ffffffeb) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385 bpf_movein(ffff800027f335c8,ffff800000bf8800,ffff800027f33328,ffff800027f33228) at bpf_movein+0x25e sys/net/bpf.c:228 bpfwrite(41700,ffff800027f335c8,1) at bpfwrite+0x128 sys/net/bpf.c:648 spec_write(ffff800027f33420) at spec_write+0xcb sys/kern/spec_vnops.c:309 VOP_WRITE(fffffd8073332b08,ffff800027f335c8,1,fffffd807f7d8480) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245 vn_write(fffffd8067d9f978,ffff800027f335c8,0) at vn_write+0x152 sys/kern/vfs_vnops.c:414 dofilewritev(ffff80002161ea80,3,ffff800027f335c8,0,ffff800027f336c0) at dofilewritev+0x19c sys/kern/sys_generic.c:380 sys_write(ffff80002161ea80,ffff800027f33668,ffff800027f336c0) at sys_write+0x83 sys/kern/sys_generic.c:300 syscall(ffff800027f33730) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xa8b00ac8f10, count: -13 ddb> show registers rdi 0 rsi 0x1 rbp 0xffff800027f33050 rbx 0x30 rdx 0xffff800000bc2600 rcx 0 rax 0xffff80002161ea80 r8 0 r9 0x8080808080808080 r10 0xdafc4fff50aac5fd r11 0x9493992ae9870271 r12 0 r13 0xffffffeb r14 0 r15 0x1 rip 0xffffffff8172f728 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff800027f33040 ss 0x10 db_enter+0x18: addq $0x8,%rsp ddb> show proc PROC (syz-executor.4) pid=391647 stat=onproc flags process=0 proc=4000000 pri=32, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff800028b6c2b0,0xffffffff829b39d0 process=0xffff800024aedb88 user=0xffff800027f2e000, vmspace=0xfffffd807f018660 estcpu=36, cpticks=1, pctcpu=0.0 user=0, sys=1, intr=0 ddb> ps PID TID PPID UID S FLAGS WAIT COMMAND 56883 457330 10465 0 2 0 syz-executor.0 56883 430643 10465 0 3 0x4000080 fifow syz-executor.0 56883 255451 10465 0 3 0x4000080 fsleep syz-executor.0 56883 284320 10465 0 3 0x4000080 fsleep syz-executor.0 66330 243483 38732 0 2 0x480 syz-executor.1 66330 466084 38732 0 3 0x4000080 fsleep syz-executor.1 98914 421931 26585 0 2 0 syz-executor.4 *98914 391647 26585 0 7 0x4000000 syz-executor.4 88255 454814 634 0 2 0x480 syz-executor.7 88255 325926 634 0 3 0x4000080 netcon syz-executor.7 88255 37642 634 0 3 0x4000080 netcon syz-executor.7 88255 479718 634 0 3 0x4000080 fsleep syz-executor.7 39354 247315 67188 0 2 0x2 syz-executor.3 10465 324652 67188 0 3 0x82 nanoslp syz-executor.0 634 105485 67188 0 2 0x482 syz-executor.7 27603 268716 0 0 3 0x14280 nfsidl nfsio 36244 16737 0 0 3 0x14280 nfsidl nfsio 78324 373873 0 0 3 0x14280 nfsidl nfsio 24826 63336 0 0 3 0x14280 nfsidl nfsio 81087 113383 0 0 3 0x14280 nfsidl nfsio 98694 17758 0 0 3 0x14280 nfsidl nfsio 49964 271063 0 0 3 0x14200 bored sosplice 16454 375348 67188 0 2 0x2 syz-executor.6 53847 272912 67188 0 2 0x482 syz-executor.5 26585 515405 67188 0 3 0x82 nanoslp syz-executor.4 38732 391484 67188 0 2 0x482 syz-executor.1 89665 427791 67188 0 2 0x482 syz-executor.2 67188 331006 23099 0 3 0x82 thrsleep syz-fuzzer 67188 372167 23099 0 3 0x4000082 nanoslp syz-fuzzer 67188 424195 23099 0 3 0x4000082 thrsleep syz-fuzzer 67188 2373 23099 0 3 0x4000082 kqread syz-fuzzer 67188 182217 23099 0 3 0x4000082 thrsleep syz-fuzzer 67188 35798 23099 0 3 0x4000082 thrsleep syz-fuzzer 67188 356756 23099 0 3 0x4000082 thrsleep syz-fuzzer 67188 429971 23099 0 3 0x4000082 thrsleep syz-fuzzer 67188 206945 23099 0 3 0x4000082 thrsleep syz-fuzzer 23099 486287 1425 0 3 0x10008a sigsusp ksh 1425 411083 80406 0 3 0x9a poll sshd 21538 104676 1 0 3 0x100083 ttyin getty 80406 519700 1 0 3 0x88 poll sshd 92153 44724 21279 73 3 0x100090 kqread syslogd 21279 200516 1 0 3 0x100082 netio syslogd 75286 264191 1 0 3 0x100080 kqread resolvd 46612 294112 510 77 3 0x100092 kqread dhcpleased 43197 32440 510 77 3 0x100092 kqread dhcpleased 510 164747 1 0 3 0x80 kqread dhcpleased 31943 380432 0 0 3 0x14200 bored smr 29745 214436 0 0 2 0x14200 zerothread 1383 103860 0 0 3 0x14200 aiodoned aiodoned 87561 230387 0 0 3 0x14200 syncer update 19808 254644 0 0 3 0x14200 cleaner cleaner 31627 378 0 0 3 0x14200 reaper reaper 19262 210304 0 0 3 0x14200 pgdaemon pagedaemon 27823 103146 0 0 3 0x14200 bored viomb 83237 441508 0 0 3 0x40014200 acpi0 acpi0 94628 366994 0 0 3 0x14200 bored softnet 58912 409040 0 0 3 0x14200 bored systqmp 52300 396248 0 0 3 0x14200 bored systq 7172 311557 0 0 2 0x40014200 softclock 67204 469251 0 0 3 0x40014200 idle0 1 355720 0 0 3 0x80082 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 10195 6597K 7504K 78643K 15688 0 pcb 13 12K 14K 78643K 213 0 rtable 270 13K 16K 78643K 742 0 ifaddr 87 18K 19K 78643K 288 0 sysctl 2 0K 0K 78643K 2 0 counters 27 17K 17K 78643K 44 0 ioctlops 0 0K 4K 78643K 518 0 iov 0 0K 16K 78643K 151 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 4 0 vnodes 1347 84K 84K 78643K 3019 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 9K 78643K 24 0 VM map 2 0K 0K 78643K 2 0 sem 12 0K 0K 78643K 200 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12548 0 file desc 14 49K 77K 78643K 1186 0 sigio 0 0K 0K 78643K 48 0 proc 61 55K 71K 78643K 643 0 subproc 104 6K 6K 78643K 169 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 ip_moptions 0 0K 0K 78643K 37 0 in_multi 99 6K 6K 78643K 166 0 ether_multi 1 0K 0K 78643K 10 0 mrt 0 0K 0K 78643K 6 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 151 678K 678K 78643K 151 0 exec 0 0K 2K 78643K 953 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 317 211K 1057K 78643K 15686 0 UVM aobj 93 3K 3K 78643K 95 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 ip6_options 0 0K 0K 78643K 18 0 NDP 11 0K 1K 78643K 54 0 temp 129 4699K 4763K 78643K 14127 0 kqueue 10 14K 20K 78643K 72 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 120 226 0 223 5 2 3 3 0 8 2 rtentry 112 179 0 66 4 0 4 4 0 8 0 unpcb 136 1232 0 1217 11 10 1 9 0 8 0 syncache 296 11 0 11 3 3 0 1 0 8 0 tcpqe 32 1 0 1 1 1 0 1 0 8 0 tcpcb 736 199 0 192 9 7 2 8 0 8 0 arp 88 31 0 13 1 0 1 1 0 8 0 inpcb 304 847 0 838 11 5 6 6 0 8 5 nd6 48 43 0 16 1 0 1 1 0 8 0 kcovpl 48 13 0 5 1 0 1 1 0 8 0 ppxss 1152 3 0 3 1 0 1 1 0 8 1 pfstscr 40 6 0 5 1 0 1 1 0 8 0 pfrktable 1344 76 0 65 3 1 2 2 0 8 0 pftag 88 1 0 0 1 0 1 1 0 8 0 pfstitem 24 8 0 6 1 0 1 1 0 8 0 pfstkey 112 12 0 10 1 0 1 1 0 8 0 pfstate 320 6 0 5 1 0 1 1 0 8 0 pfrule 1360 131 0 115 3 1 2 2 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 696 0 226 30 0 30 30 0 8 0 art_table 32 697 0 226 4 0 4 4 0 8 0 art_node 16 178 0 75 1 0 1 1 0 8 0 sysvmsgpl 40 2 0 0 1 0 1 1 0 8 0 semapl 112 198 0 188 1 0 1 1 0 8 0 shmpl 112 92 0 2 4 1 3 3 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 3074 0 1636 91 0 91 91 0 8 0 ffsino 240 3074 0 1636 85 0 85 85 0 8 0 nchpl 144 4763 0 3137 63 0 63 63 0 8 0 uvmvnodes 80 4609 0 0 95 0 95 95 0 8 0 vnodes 224 4609 0 0 272 0 272 272 0 8 0 namei 1024 19480 0 19478 2 1 1 2 0 8 0 vcpupl 1984 9 0 0 2 0 2 2 0 8 0 vmpool 528 12 0 3 1 0 1 1 0 8 0 pfiaddrpl 120 31 0 18 2 1 1 1 0 8 0 scxspl 216 14448 0 14448 10 9 1 8 0 8 1 plimitpl 152 139 0 125 1 0 1 1 0 8 0 sigapl 424 1468 0 1423 7 1 6 6 0 8 0 futexpl 64 11908 0 11904 1 0 1 1 0 8 0 knotepl 112 722 0 648 3 0 3 3 0 8 0 kqueuepl 184 322 0 314 5 3 2 4 0 8 1 pipepl 304 249 0 220 8 5 3 8 0 8 0 fdescpl 432 1448 0 1423 4 0 4 4 0 8 0 filepl 120 11247 0 10999 27 13 14 20 0 8 6 lockfpl 104 561 0 558 2 1 1 2 0 8 0 lockfspl 48 86 0 83 1 0 1 1 0 8 0 sessionpl 144 28 0 12 1 0 1 1 0 8 0 pgrppl 48 48 0 32 1 0 1 1 0 8 0 ucredpl 96 1455 0 1445 1 0 1 1 0 8 0 zombiepl 144 1423 0 1421 1 0 1 1 0 8 0 processpl 1000 1468 0 1421 7 0 7 7 0 8 0 procpl 672 3119 0 3056 8 1 7 7 0 8 1 sosppl 168 11 0 11 2 2 0 1 0 8 0 sockpl 448 2307 0 2280 52 41 11 30 0 8 7 mcl64k 65536 93 0 93 2 1 1 1 0 8 1 mcl16k 16384 18 0 18 3 2 1 1 0 8 1 mcl12k 12288 51 0 51 2 1 1 1 0 8 1 mcl9k 9216 17 0 17 3 2 1 1 0 8 1 mcl8k 8192 80 0 80 2 1 1 1 0 8 1 mcl4k 4096 133 0 133 2 1 1 1 0 8 1 mcl2k2 2112 10 0 10 3 2 1 1 0 8 1 mcl2k 2048 77141 0 77025 19 3 16 16 0 8 0 mtagpl 96 234 0 63 6 1 5 5 0 8 0 mbufpl 256 129506 0 129119 49 17 32 48 0 8 5 bufpl 288 6181 0 143 432 0 432 432 0 8 0 anonpl 24 375250 0 358051 144 24 120 141 0 188 3 amapchunkpl 152 364979 0 364210 4899 4737 162 4423 0 158 129 amappl16 200 3599 0 2986 46 12 34 46 0 8 0 amappl15 192 393 0 384 1 0 1 1 0 8 0 amappl14 184 45 0 42 1 0 1 1 0 8 0 amappl13 176 112 0 110 1 0 1 1 0 8 0 amappl12 168 204 0 200 1 0 1 1 0 8 0 amappl11 160 208 0 196 1 0 1 1 0 8 0 amappl10 152 27 0 25 1 0 1 1 0 8 0 amappl9 144 829 0 821 1 0 1 1 0 8 0 amappl8 136 676 0 622 2 0 2 2 0 8 0 amappl7 128 153 0 143 1 0 1 1 0 8 0 amappl6 120 580 0 559 2 1 1 2 0 8 0 amappl5 112 992 0 978 1 0 1 1 0 8 0 amappl4 104 1162 0 1131 2 0 2 2 0 8 0 amappl3 96 460 0 447 1 0 1 1 0 8 0 amappl2 88 796 0 750 3 1 2 3 0 8 0 amappl1 80 28757 0 28215 19 6 13 18 0 8 0 amappl 88 15135 0 14907 8 1 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 94 0 2 2 0 2 2 0 8 0 uaddrrnd 24 1460 0 1426 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 1460 0 1426 1 0 1 1 0 8 0 vmmpekpl 168 14627 0 14574 3 0 3 3 0 8 0 vmmpepl 168 138564 0 136207 131 8 123 126 0 357 7 vmsppl 272 1459 0 1426 4 1 3 3 0 8 0 rwobjpl 24 37966 0 31724 38 0 38 38 0 8 0 pdppl 4096 2926 0 2861 153 80 73 73 0 8 8 pvpl 32 744663 0 723727 240 43 197 238 0 265 7 pmappl 216 1459 0 1426 3 0 3 3 0 8 0 extentpl 40 58 0 38 1 0 1 1 0 8 0 phpool 112 945 0 158 23 0 23 23 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(ffffffff8254be5b) at panic+0x161 sys/kern/subr_prf.c:202 __assert(ffffffff825bbf89,ffffffff825cdd9d,568,ffffffff8255ec6a) at __assert+0x25 sys/kern/subr_prf.c:161 m_align(fffffd80684fe900,ffffffeb) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385 bpf_movein(ffff800027f335c8,ffff800000bf8800,ffff800027f33328,ffff800027f33228) at bpf_movein+0x25e sys/net/bpf.c:228 bpfwrite(41700,ffff800027f335c8,1) at bpfwrite+0x128 sys/net/bpf.c:648 spec_write(ffff800027f33420) at spec_write+0xcb sys/kern/spec_vnops.c:309 VOP_WRITE(fffffd8073332b08,ffff800027f335c8,1,fffffd807f7d8480) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245 vn_write(fffffd8067d9f978,ffff800027f335c8,0) at vn_write+0x152 sys/kern/vfs_vnops.c:414 dofilewritev(ffff80002161ea80,3,ffff800027f335c8,0,ffff800027f336c0) at dofilewritev+0x19c sys/kern/sys_generic.c:380 sys_write(ffff80002161ea80,ffff800027f33668,ffff800027f336c0) at sys_write+0x83 sys/kern/sys_generic.c:300 syscall(ffff800027f33730) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xa8b00ac8f10, 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(ffffffff8254be5b) at panic+0x161 sys/kern/subr_prf.c:202 __assert(ffffffff825bbf89,ffffffff825cdd9d,568,ffffffff8255ec6a) at __assert+0x25 sys/kern/subr_prf.c:161 m_align(fffffd80684fe900,ffffffeb) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385 bpf_movein(ffff800027f335c8,ffff800000bf8800,ffff800027f33328,ffff800027f33228) at bpf_movein+0x25e sys/net/bpf.c:228 bpfwrite(41700,ffff800027f335c8,1) at bpfwrite+0x128 sys/net/bpf.c:648 spec_write(ffff800027f33420) at spec_write+0xcb sys/kern/spec_vnops.c:309 VOP_WRITE(fffffd8073332b08,ffff800027f335c8,1,fffffd807f7d8480) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245 vn_write(fffffd8067d9f978,ffff800027f335c8,0) at vn_write+0x152 sys/kern/vfs_vnops.c:414 dofilewritev(ffff80002161ea80,3,ffff800027f335c8,0,ffff800027f336c0) at dofilewritev+0x19c sys/kern/sys_generic.c:380 sys_write(ffff80002161ea80,ffff800027f33668,ffff800027f336c0) at sys_write+0x83 sys/kern/sys_generic.c:300 syscall(ffff800027f33730) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xa8b00ac8f10, count: -13