Re: Ugly rmap NULL ptr deref oopsie on hibernate (was Linux2.6.34-rc3)

From: Borislav Petkov
Date: Wed Apr 07 2010 - 03:29:16 EST

From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Tue, Apr 06, 2010 at 04:27:42PM -0700

> No, you're mis-reading the asm. It's again the first iteration, and the
> code above it is again the end of the loop. And %rax is once more a kernel
> pointer, not the return value of 'page_referenced_one()'.
> So it once more is 'anon_vma->' that is crap, but now it's not
> NULL, it's that very odd 0x002e2e2e002e2e2e pattern (the %r13 has had 0x20
> subtracted from it, so that LSB of "0x0e" is actually _also_ a 0x2e).

No, maybe I expressed myself wrong (it was late an' all) - I was
basically trying to confirm your assessment that anon_vma->
is crap but the code had changed since I had added the debugging 'if
(!anon_vma->' and that was the value that was already in %r13
before iterating over the list chain.

Yeah, just a minor nitpick and not that it matters. Nevermind though,
we're on the same page.

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