panic: kernel diagnostic assertion "M_DATABUF(m) + M_SIZE(m) >= (m->m_data + m->m_len)" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/uipc_mbuf.c", line 1335 Stopped at db_enter+0xa: popq %rbp TID PID UID PRFLAGS PFLAGS CPU COMMAND 463756 74762 0 0 0 0 syz-executor1 *286358 74762 0 0 0x4000000 1K syz-executor1 db_enter() at db_enter+0xa panic() at panic+0x147 __assert(ffffffff81521464,ffff8000210bd980,ffffff00651d1d04,c) at __assert+0x24 m_copyback(ffffff00651d1cf8,ffffff00651d1c00,8,0,0) at m_copyback+0x4e9 swofp_send_error(ffff800001aeb800,ffffff00651d1c00,ffff800001adfb00,ffffffff81b2cc70) at swofp_send_error+0xac swofp_recv_hello(ffffff00651d1c00,ffff800001aeb800) at swofp_recv_hello+0x3f swofp_input(ffff800001aeb800,ffff8000210bdb18) at swofp_input+0xfe switchwrite(ffffff0075dc5c50,ffffff0075dc5c50,ffff8000210bdcf8) at switchwrite+0x30e spec_write(ffffffff81e4c3d0) at spec_write+0xa8 VOP_WRITE(1,ffffff0075dc5c50,1,ffffff0074a5f9d8) at VOP_WRITE+0x65 vn_write(ffffff0074a5f9d8,ffff8000210bdcf8,87) at vn_write+0x161 dofilewritev(ffff8000210bde20,1,ffff8000210bde38,ffff8000210a2bd0,0) at dofilewritev+0x13e sys_pwritev(10c0,ffff8000210a2bd0,0) at sys_pwritev+0xbf syscall(0) at syscall+0x489 end trace frame: 0xffff8000210bdf40, count: 0 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}> show panic kernel diagnostic assertion "M_DATABUF(m) + M_SIZE(m) >= (m->m_data + m->m_len)" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/uipc_mbuf.c", line 1335 ddb{1}> trace db_enter() at db_enter+0xa panic() at panic+0x147 __assert(ffffffff81521464,ffff8000210bd980,ffffff00651d1d04,c) at __assert+0x24m_copyback(ffffff00651d1cf8,ffffff00651d1c00,8,0,0) at m_copyback+0x4e9 swofp_send_error(ffff800001aeb800,ffffff00651d1c00,ffff800001adfb00,ffffffff81b2cc70) at swofp_send_error+0xac swofp_recv_hello(ffffff00651d1c00,ffff800001aeb800) at swofp_recv_hello+0x3f swofp_input(ffff800001aeb800,ffff8000210bdb18) at swofp_input+0xfe switchwrite(ffffff0075dc5c50,ffffff0075dc5c50,ffff8000210bdcf8) at switchwrite+0x30e spec_write(ffffffff81e4c3d0) at spec_write+0xa8 VOP_WRITE(1,ffffff0075dc5c50,1,ffffff0074a5f9d8) at VOP_WRITE+0x65 vn_write(ffffff0074a5f9d8,ffff8000210bdcf8,87) at vn_write+0x161 dofilewritev(ffff8000210bde20,1,ffff8000210bde38,ffff8000210a2bd0,0) at dofilewritev+0x13e sys_pwritev(10c0,ffff8000210a2bd0,0) at sys_pwritev+0xbf syscall(0) at syscall+0x489 Xsyscall(6,0,ffffffffffffffb8,0,4,cc38522a1a0) at Xsyscall+0x128 end of kernel end trace frame: 0xcc66c463cf0, count: -15 ddb{1}> show registers rdi 0xffffffff81e2ec58 kprintf_mutex rsi 0xffffffff81b67d99 db_enter+0x9 rbp 0xffff8000210bd8e0 rbx 0xffff8000210bd980 rdx 0xffff800002ed7000 rcx 0x3dc0 __ALIGN_SIZE+0x2dc0 rax 0xffff800002ed7000 r8 0xffff8000210bd8b0 r9 0x8080808080808080 r10 0 r11 0xffffffff819e6130 x86_bus_space_io_read_1 r12 0x3000000008 r13 0xffff8000210bd8f0 r14 0x100 r15 0xffffffff81bf400f cmd0646_9_tim_udma+0x20bde rip 0xffffffff81b67d9a db_enter+0xa cs 0x8 rflags 0x216 rsp 0xffff8000210bd8e0 ss 0x10 db_enter+0xa: popq %rbp ddb{1}> show proc PROC (syz-executor1) pid=286358 stat=onproc flags process=0 proc=4000000 pri=83, usrpri=83, nice=20 forw=0xffffffffffffffff, list=0xffff8000210a3788,0xffffffff81eac508 process=0xffff8000210b6cc0 user=0xffff8000210b8000, vmspace=0xffffff007ded1d80 estcpu=33, cpticks=1, pctcpu=0.0 user=0, sys=1, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 74762 463756 65445 0 7 0 syz-executor1 74762 345040 65445 0 3 0x4000080 switchread syz-executor1 74762 335737 65445 0 2 0x4000000 syz-executor1 *74762 286358 65445 0 7 0x4000000 syz-executor1 99950 249099 1 0 3 0x100083 ttyin getty 57709 216916 0 0 3 0x14200 bored sosplice 65445 283176 85334 0 3 0x82 nanosleep syz-executor1 35980 48958 85334 0 3 0x82 piperd syz-executor0 85334 94144 64611 0 3 0x82 thrsleep syz-fuzzer 85334 8232 64611 0 3 0x4000082 thrsleep syz-fuzzer 85334 136445 64611 0 3 0x4000082 thrsleep syz-fuzzer 85334 359748 64611 0 3 0x4000082 thrsleep syz-fuzzer 85334 336510 64611 0 3 0x4000082 thrsleep syz-fuzzer 85334 466923 64611 0 3 0x4000082 thrsleep syz-fuzzer 85334 144645 64611 0 3 0x4000082 thrsleep syz-fuzzer 85334 363247 64611 0 3 0x4000082 kqread syz-fuzzer 85334 416249 64611 0 3 0x4000082 thrsleep syz-fuzzer 85334 293991 64611 0 3 0x4000082 thrsleep syz-fuzzer 85334 303126 64611 0 3 0x4000082 thrsleep syz-fuzzer 64611 186375 57807 0 3 0x10008a pause ksh 57807 473925 63829 0 3 0x92 select sshd 63829 179436 1 0 3 0x80 select sshd 39250 401142 15203 73 3 0x100090 kqread syslogd 15203 500713 1 0 3 0x100082 netio syslogd 33222 67254 0 0 3 0x14200 pgzero zerothread 78567 514287 0 0 3 0x14200 aiodoned aiodoned 2772 503321 0 0 3 0x14200 syncer update 11546 213528 0 0 3 0x14200 cleaner cleaner 90871 512219 0 0 3 0x14200 reaper reaper 81402 159823 0 0 3 0x14200 pgdaemon pagedaemon 81541 510588 0 0 3 0x14200 bored crynlk 36174 356207 0 0 3 0x14200 bored crypto 50208 519247 0 0 3 0x40014200 acpi0 acpi0 2130 454761 0 0 3 0x40014200 idle1 69053 182128 0 0 3 0x14200 bored softnet 4156 221074 0 0 3 0x14200 bored systqmp 15446 192575 0 0 3 0x14200 bored systq 30306 94101 0 0 3 0x40014200 bored softclock 10470 45713 0 0 3 0x40014200 idle0 1 501279 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper