On Mon, Jan 11, 2016 at 4:51 AM, Andrey Ryabinin
[off-list ref] wrote:

Currently we clear kasan_zero_page before __flush_tlb_all(). This
works with current implementation of native_flush_tlb[_global]()
because it doesn't cause do any writes to kasan shadow memory.
But any subtle change made in native_flush_tlb*() could break this.
Also current code seems doesn't work for paravirt guests (lguest).

Only after the TLB flush we can be sure that kasan_zero_page is not
used as early shadow anymore (instrumented code will not write to it).
So it should cleared it only after the TLB flush.

This seems to fix the issue with my patch set.  Thanks.

Tested-by: Andy Lutomirski <luto@kernel.org>

--Andy

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