Messages in this thread | | | Date | Fri, 11 Dec 2015 09:14:34 +0100 | From | Ingo Molnar <> | Subject | Re: use-after-free in __perf_install_in_context |
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* Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
> On Thu, Dec 10, 2015 at 10:02:51AM +0100, Peter Zijlstra wrote: > > On Wed, Dec 09, 2015 at 07:54:35PM -0800, Alexei Starovoitov wrote: > > > Freeing memory is a requirement regardless. > > > Even when kernel running with kasan, there must be a way to stop > > > stack collection and free that memory. > > > You cannot treat kernel as your test program or 'device under test'. > > > > Relax, that is exactly what lockdep does. It cannot dynamically allocate > > things because allocators use lock etc.. > > > > Its fine to build up state for debug bits, esp. if its bounded, like the > > number of unique callchains. > > except the code in question is doing unbounded alloc_pages()
Yes, but the trick is to still have a bound sized debug pool - which runs out of entries gracefully.
Which in practice is plenty enough for most types of testing, and is a lot more robust than any dynamic scheme.
Thanks,
Ingo
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