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    SubjectRe: [PATCH] x86, x86_64: Fix checks for userspace address limit

    * Linus Torvalds <> wrote:

    > On Mon, May 16, 2011 at 4:42 AM, Ingo Molnar <> wrote:
    > >
    > > Hm, something tickles me about this area that we would reintroduce a security
    > > hole, that we really wanted to treat the last page of user-space as some sort
    > > of guard page but i cannot quite remember it why ...
    > >
    > > IIRC Linus wrote bits of this so i'm Cc:-ing him just in case he remembers.
    > No, I suspect the patch is correct, and it's just a bug. I think it
    > comes from the "get_user_X()" cases that afaik use "jae" because they
    > add one less than the size (and thus avoid it entirely for the
    > single-byte case). See "getuser.S" in the same directory.
    > But right now I think I need to do a 2.6.39 release later today (after
    > I get some sleep), so doing it as a stable patch (presumably going
    > back to pretty much the beginning of time) is probably the right
    > thing.

    Absolutely - we had this for a long time so it's not a regression and there is
    very little gain from trying to squeeze this fix in so close to v2.6.39 - and
    there are nonzero risks, considering how widely used assembly code this

    I've queued it up for v2.6.40 with your Acked-by.



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