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Re: CVS commit: src/sys/kern
Le 16/08/2019 à 00:05, matthew green a écrit :
KMEM_GUARD is useful for platforms that don't have kasan yet.
Verily it was not.
1) The place where diagnostic/debug features should be implemented is pool(9),
not kmem(9). Pools represent all of the dynamic system memory, kmem only a
small subset of that. KMEM_GUARD was unable to detect anything on mbufs,
pnbufs, vnodes, etc.
2) The pool hardening enabled by default in GENERIC is more powerful in
detecting inconsistencies - like  -, and does more than half of
KMEM_GUARD's work with basically no overhead.
3) The additional POOL_REDZONE option can be used to detect more bugs on all
pools and not just kmem. But see below.
We need to stop with these useless debug-only options that nobody uses, and
which moreover are implemented in the wrong place and can detect nothing.
Le 16/08/2019 à 07:46, Nick Hudson a écrit :
yet? Can 32bit platforms and limit KVA have KASAN?
If you are telling me they could reliably use KMEM_GUARD before, then it
likely means they can have KASAN. If you want to add KASAN to more arches,
feel free to, I made it largely MI, so the MD effort needed is limited.
By the way, can we turn on POOL_REDZONE under DIAGNOSTIC now? Last time I
tried to do that you complained to me that ARM wasn't booting anymore, until
it turned out it was a bug in ARM which you later fixed. Would be nice to
hear about that, because POOL_REDZONE *is* the kind of feature that is useful.
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