Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 20 Sep 2016 13:48:10 -0700 | Subject | Re: [PATCH] fix fault_in_multipages_...() on architectures with no-op access_ok() |
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On Tue, Sep 20, 2016 at 1:38 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > > Not the point. Of course it *would* fail; the problem is that the loop > that would ping each page is never executed.
You're missing the point.
If "access_ok()" is fine with wrapping, then some otehr system call that wraps will successfully do a memcpy_from/to_user() with a wrapped address (and the proper mappings). Which is completely bogus.
So access_ok() should be fixed regardless. An access_ok() that accepts a wrapping address is a bug. End of story.
And once that bug is fixed, the fault_in_multipages..() issue is moot. So it shouldn't be an issue.
Linus
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