On Tue, Jan 22, 2019 at 8:15 AM Greg KH <gre...@linuxfoundation.org> wrote: > > On Mon, Jan 21, 2019 at 10:36:18AM -0800, Andi Kleen wrote: > > > + /* Check the start address: needs to be page-aligned.. */ > > > +- if (start & ~PAGE_MASK) > > > ++ if (start & ~PAGE_MASK) { > > > ++ > > > ++ /* > > > ++ * XXX Hack > > > ++ * > > > ++ * We re-use this error case to show case a cache load gadget: > > > ++ * There is a mispredicted branch, which leads to prefetching > > > ++ * the cache with attacker controlled data. > > > ++ */ > > > ++ asm volatile ( > > > > Obviously that can never be added to a standard kernel. > > No, that's why it is a patch, right? People want to test things, it's > nice to have a way to easily do this.
What about adding something like it to drivers/misc/lkdtm/ instead? It's not a "production" module, but it regularly get built for selftest builds. -- Kees Cook