> I looked at this a couple on months back (and posted something to
> security audit about some concerns I had).
>
> Basically... if you pass bogus addresses and pointers to the kernel,
> depending on what OS and version you are running, you might get an
> EFAULT and you might not.
no, it's a quality of implementation issue. Also it's a usability issue,
bugs detected should be reported back to user-space. It's _not_ a valid
excuse that if it's not defined explicitly in POSIX or that other OSs are
less careful.
Also, it can be used by user-space too, if a memory-management software
(such as a C++ wrapped garbage collector or whatever) maps/unmaps certain
areas of memory, the pointer could be invalid because say that page is
marked read-only, but user-space has the right to detect this. Thus such
'temporarily invalid pointers' detected by the kernel as 'invalid pointer'
can be turned into a 'valid pointer' by user-space wrapping functions. (i
dont think there is any such package for Linux right now)
-- mingo
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