Messages in this thread | | | Date | Tue, 20 Oct 2009 08:14:15 +0200 | From | Ingo Molnar <> | Subject | Re: Withdraw: [PATCH] x86-64: fix another kernel data leak to 32-bit processes |
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* 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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