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SubjectRe: Withdraw: [PATCH] x86-64: fix another kernel data leak to 32-bit processes

* Jan Beulich <JBeulich@novell.com> wrote:

> >Unfortunately I didn't realize that the other instances of branches
> >to int_ret_from_sys_call also need fixing when preparing the previous
> >similar patch. The issue fixed here was in fact introduced by an
> >earlier patch of mine (295286a89107c353b9677bc604361c537fd6a1c0, i.e.
> >in 2.6.28, but through stable now also present in 2.6.27), making
> >kernel stack contents potentially visible through R8...R11 when an
> >this or earlier syscall got interrupted prior to the handler being
> >able to decrement the stack pointer (such that the space normally
> >used by those registers within pt_regs would get overwritten by the
> >interrupt handler stub).
>
> That analysis wasn't right after all - there's a CLEAR_RREGS in each
> of the modified paths already, so the change is unnecessary (and
> adding redundant code). Please don't apply it.
>
> >While touching the code, I also swapped the branch pairs so that the
> >static branch prediction logic would consider the syscall-number-in-
> >range case the taken path.
>
> If this would seem a worthwhile change, I can re-send it as a
> separate, lower priority patch...

Please do - thanks!

Ingo


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