kprobes/x86: Use copy_from_kernel_nofault() to read from unsafe address

In the Linux kernel, the following vulnerability has been resolved:

kprobes/x86: Use copy_from_kernel_nofault() to read from unsafe address

Read from an unsafe address with copy_from_kernel_nofault() in

arch_adjust_kprobe_addr() because this function is used before checking

the address is in text or not. Syzcaller bot found a bug and reported

the case if user specifies inaccessible data area,

arch_adjust_kprobe_addr() will cause a kernel panic.

[ mingo: Clarified the comment. ]