Re: [patch 2.6.13-rc4] fix get_user_pages bug

Linus Torvalds
2005-08-02T03:45:52Z

On Tue, 2 Aug 2005, Nick Piggin wrote:
>
> Surely this introduces integrity problems when `force` is not set?

"force" changes how we test the vma->vm_flags, that was always the
meaning from a security standpoint (and that hasn't changed).

The old code had this "lookup_write = write && !force;" thing because
there it used "force" to _clear_ the write bit test, and that was what
caused the race in the first place - next time around we would accept a
non-writable page, even if it hadn't actually gotten COW'ed.

So no, the patch doesn't introduce integrity problems by ignoring "force".
Quite the reverse - it _removes_ the integrity problems by ignoring it
there. That's kind of the whole point.

Linus