Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode

Russell King - ARM Linux
2017-05-12T20:21:06Z

On Fri, May 12, 2017 at 12:30:02PM -0700, Kees Cook wrote:
> I'm clearly not explaining things well enough. I shouldn't say
> "corruption", I should say "malicious manipulation". The methodology
> of attacks against the stack are quite different from the other kinds
> of attacks like use-after-free, heap overflow, etc. Being able to
> exhaust the kernel stack (either due to deep recursion or unbounded
> alloca())

I really hope we don't have alloca() use in the kernel. Do you have
evidence to support that assertion?

IMHO alloca() (or similar) should not be present in any kernel code
because we have a limited stack - we have kmalloc() etc for that kind
of thing.

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