Messages in this thread | | | Date | Sat, 30 May 2009 03:43:39 -0700 | From | "Larry H." <> | Subject | Re: [patch 0/5] Support for sanitization flag in low-level page allocator |
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On 12:39 Sat 30 May , Peter Zijlstra wrote: > > Because zero on allocate kills the very purpose of this patch and it has > > obvious security implications. Like races (in information leak > > scenarios, that is). What happens in-between the release of the page and > > the new allocation that yields the same page? What happens if no further > > allocations happen in a while (that can return the old page again)? > > That's the idea. > > I don't get it, these are in-kernel data leaks, you need to be able to > run kernel code to exploit these, if someone can run kernel code, you've > lost anyhow. > > Why waste time on this?
If there were any hesitations about your lack of understanding in security matters, you just cleared them all with the above statements.
> > > So if you zero on free, the next allocation will reuse the zeroed page. > > > And due to LIFO that is not too far out "often", which makes it likely > > > the page is still in L2 cache. > > > > Thanks for pointing this out clearly, Arjan. > > Thing is, the time between allocation and use is typically orders of > magnitude less than between free and use. > > > Really, get a life, go fix real bugs. Don't make our kernel slower for > wanking rights.
This is exactly the positive attitude, sound and mature response I was expecting from you. Thank you.
Larry
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