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 337781 32296 0 0x1000 0x4080080 0 syz-executor0 *278183 32296 0 0x1000 0x4080000 1K syz-executor0 db_enter() at db_enter+0xa panic() at panic+0x147 __assert(ffffffff81521464,ffff8000211b3080,ffffff006592c204,c) at __assert+0x24 m_copyback(ffffff006592c1f8,ffffff006592c100,8,0,0) at m_copyback+0x4e9 swofp_send_error(ffff800001af2800,ffffff006592c100,ffff800001ae3e80,ffffffff81b2cc70) at swofp_send_error+0xac swofp_recv_hello(ffffff006592c100,ffff800001af2800) at swofp_recv_hello+0x3f swofp_input(ffff800001af2800,ffff8000211b3218) at swofp_input+0xfe switchwrite(ffffff005fe1e218,ffffff005fe1e218,ffff8000211b33f8) at switchwrite+0x30e spec_write(ffffffff81e4c3d0) at spec_write+0xa8 VOP_WRITE(1,ffffff005fe1e218,1,ffffff0068512e20) at VOP_WRITE+0x65 vn_write(ffffff0068512e20,ffff8000211b33f8,87) at vn_write+0x161 dofilewritev(ffff8000211b3520,1,ffff8000211b3538,ffff8000210a24c8,0) at dofilewritev+0x13e sys_pwritev(10c0,ffff8000210a24c8,0) at sys_pwritev+0xbf syscall(0) at syscall+0x489 end trace frame: 0xffff8000211b3640, 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,ffff8000211b3080,ffffff006592c204,c) at __assert+0x24m_copyback(ffffff006592c1f8,ffffff006592c100,8,0,0) at m_copyback+0x4e9 swofp_send_error(ffff800001af2800,ffffff006592c100,ffff800001ae3e80,ffffffff81b2cc70) at swofp_send_error+0xac swofp_recv_hello(ffffff006592c100,ffff800001af2800) at swofp_recv_hello+0x3f swofp_input(ffff800001af2800,ffff8000211b3218) at swofp_input+0xfe switchwrite(ffffff005fe1e218,ffffff005fe1e218,ffff8000211b33f8) at switchwrite+0x30e spec_write(ffffffff81e4c3d0) at spec_write+0xa8 VOP_WRITE(1,ffffff005fe1e218,1,ffffff0068512e20) at VOP_WRITE+0x65 vn_write(ffffff0068512e20,ffff8000211b33f8,87) at vn_write+0x161 dofilewritev(ffff8000211b3520,1,ffff8000211b3538,ffff8000210a24c8,0) at dofilewritev+0x13e sys_pwritev(10c0,ffff8000210a24c8,0) at sys_pwritev+0xbf syscall(0) at syscall+0x489 Xsyscall(6,0,ffffffffffffffb8,0,4,b82895a71a0) at Xsyscall+0x128 end of kernel end trace frame: 0xb84ab6f3770, count: -15 ddb{1}> show registers rdi 0xffffffff81e2ec58 kprintf_mutex rsi 0xffffffff81b67d99 db_enter+0x9 rbp 0xffff8000211b2fe0 rbx 0xffff8000211b3080 rdx 0xffff800000ed6000 rcx 0x3786 __ALIGN_SIZE+0x2786 rax 0xffff800000ed6000 r8 0xffff8000211b2fb0 r9 0x8080808080808080 r10 0 r11 0xffffffff819e6130 x86_bus_space_io_read_1 r12 0x3000000008 r13 0xffff8000211b2ff0 r14 0x100 r15 0xffffffff81bf400f cmd0646_9_tim_udma+0x20bde rip 0xffffffff81b67d9a db_enter+0xa cs 0x8 rflags 0x202 rsp 0xffff8000211b2fe0 ss 0x10 db_enter+0xa: popq %rbp ddb{1}> show proc PROC (syz-executor0) pid=278183 stat=onproc flags process=1000 proc=4080000 pri=80, usrpri=80, nice=20 forw=0xffffffffffffffff, list=0xffff8000210a39e0,0xffffffff81eac508 process=0xffff8000210b6cb8 user=0xffff8000211ae000, vmspace=0xffffff007ed77430 estcpu=30, cpticks=2, pctcpu=0.0 user=0, sys=2, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 32296 483328 32364 0 3 0x3000 suspend syz-executor0 32296 337781 32364 0 7 0x4081080 syz-executor0 32296 380943 32364 0 2 0x4081080 syz-executor0 *32296 278183 32364 0 7 0x4081000 syz-executor0 65302 87631 1 0 3 0x100083 ttyin getty 28424 205280 0 0 3 0x14200 bored sosplice 572 23795 7407 0 3 0x82 piperd syz-executor1 32364 39317 7407 0 3 0x82 nanosleep syz-executor0 7407 337547 18301 0 3 0x82 thrsleep syz-fuzzer 7407 353317 18301 0 3 0x4000082 thrsleep syz-fuzzer 7407 363622 18301 0 3 0x4000082 thrsleep syz-fuzzer 7407 215392 18301 0 3 0x4000082 kqread syz-fuzzer 7407 53665 18301 0 3 0x4000082 thrsleep syz-fuzzer 7407 454498 18301 0 3 0x4000082 thrsleep syz-fuzzer 7407 488 18301 0 3 0x4000082 thrsleep syz-fuzzer 7407 238958 18301 0 3 0x4000082 thrsleep syz-fuzzer 7407 458546 18301 0 3 0x4000082 thrsleep syz-fuzzer 7407 377887 18301 0 3 0x4000082 thrsleep syz-fuzzer 7407 279463 18301 0 3 0x4000082 thrsleep syz-fuzzer 18301 232085 60529 0 3 0x10008a pause ksh 60529 102088 96372 0 3 0x92 select sshd 96372 141898 1 0 3 0x80 select sshd 42899 303278 38463 73 3 0x100090 kqread syslogd 38463 289842 1 0 3 0x100082 netio syslogd 62667 491041 1 77 3 0x100090 poll dhclient 28735 101840 1 0 3 0x80 poll dhclient 59266 180218 0 0 3 0x14200 pgzero zerothread 87833 468422 0 0 3 0x14200 aiodoned aiodoned 90866 20749 0 0 3 0x14200 syncer update 20990 391553 0 0 3 0x14200 cleaner cleaner 38168 50406 0 0 3 0x14200 reaper reaper 64000 303616 0 0 3 0x14200 pgdaemon pagedaemon 78021 283779 0 0 3 0x14200 bored crynlk 29901 345811 0 0 3 0x14200 bored crypto 50326 100035 0 0 3 0x40014200 acpi0 acpi0 35389 365804 0 0 3 0x40014200 idle1 58023 395127 0 0 3 0x14200 bored softnet 10779 316680 0 0 3 0x14200 bored systqmp 48263 506800 0 0 3 0x14200 bored systq 46069 67966 0 0 3 0x40014200 bored softclock 36042 368432 0 0 3 0x40014200 idle0 1 65636 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper