UPROBE case2: calling usb_make_str_desc(buf, 64, NULL) - expect NULL-deref panic
Fatal user address access from kernel mode from sysctl at ffffffff809d7740


Fatal trap 12: page fault while in kernel mode
cpuid = 4; lapic id = 4
fault virtual address	= 0x0
fault code		= supervisor read data, page not present
instruction pointer	= 0x8:0xffffffff809d7740
stack pointer	        = 0x10:0xfffff80117f2b740
frame pointer	        = 0x10:0xfffff80117f2b768
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 0, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 1376
current thread          = pri 6 
kernel: type 12 trap, code=0

CPU4 stopping CPUs: 0x0000002f
 stopped
Stopped at      strlen: cmpb    $0,(%rdi)
db> 
(usb_make_str_desc → strlen(NULL) at sys/bus/u4b/usb_util.c:228;
 guest wedged in DDB; reset with-src afterwards — guest_dirty 0)