panic: kernel diagnostic assertion "M_DATABUF(m) + M_SIZE(m) >= (m->m_data + m->m_len)" failed: file "/syzkaller/managers/main/kernel/sys/kern/uipc_mbuf.c", line 1335 Stopped at db_enter+0xa: popq %rbp TID PID UID PRFLAGS PFLAGS CPU COMMAND *426535 56486 0 0 0x4000000 0 syz-executor1 db_enter() at db_enter+0xa panic() at panic+0x147 __assert(ffffffff8148a714,ffff800021171ca0,ffffff007e72c504,c) at __assert+0x24 m_copyback(ffffff007e72c4f8,ffffff007e72c400,8,100,100) at m_copyback+0x4a4 swofp_send_error(ffffff007e72c400,ffff800001ad6800,ffff800002acd300,0) at swofp_send_error+0xac swofp_input(ffff800001ad6800,ffff800021171e18) at swofp_input+0x126 switchwrite(ffffff0061ae3d20,ffffff0061ae3d20,ffff800021171ff8) at switchwrite+0x30e spec_write(ffffffff81e3b9a8) at spec_write+0xa0 VOP_WRITE(1,ffffff0061ae3d20,1,ffffff0068f662e0) at VOP_WRITE+0x65 vn_write(ffffff0068f662e0,ffff800021171ff8,1) at vn_write+0x161 dofilewritev(ffff800021172120,1,ffff800021172138,ffff8000210b0290,0) at dofilewritev+0x13e sys_pwritev(ffff8000211721c0,ffff8000210b0290,ffff800021060620) at sys_pwritev+0xbf syscall(0) at syscall+0x3e4 Xsyscall(6,0,ffffffffffffffb8,0,4,c591af090d8) at Xsyscall+0x128 end of kernel end trace frame: 0xc5b64f493d0, count: 1 https://www.openbsd.org/ddb.html describes the minimum info required in bug reports. Insufficient info makes it difficult to find and fix bugs.