On Fri, 2018-09-14 at 01:14:11 UTC, Michael Neuling wrote: > This stops us from doing code patching in init sections after they've > been freed. > > In this chain: > kvm_guest_init() -> > kvm_use_magic_page() -> > fault_in_pages_readable() -> > __get_user() -> > __get_user_nocheck() -> > barrier_nospec(); > > We have a code patching location at barrier_nospec() and > kvm_guest_init() is an init function. This whole chain gets inlined, > so when we free the init section (hence kvm_guest_init()), this code > goes away and hence should no longer be patched. > > We seen this as userspace memory corruption when using a memory > checker while doing partition migration testing on powervm (this > starts the code patching post migration via > /sys/kernel/mobility/migration). In theory, it could also happen when > using /sys/kernel/debug/powerpc/barrier_nospec. > > cc: sta...@vger.kernel.org # 4.13+ > Signed-off-by: Michael Neuling <mi...@neuling.org> > Reviewed-by: Nicholas Piggin <npig...@gmail.com> > Reviewed-by: Christophe Leroy <christophe.le...@c-s.fr>
Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/51c3c62b58b357e8d35e4cc32f7b4e cheers
