On Sun, Sep 02, 2018 at 10:32:18AM -0700, Nadav Amit wrote: > This patch-set addresses some issues that were raised in a recent > correspondence and might affect the security and the correctness of code > patching. (Note that patching performance is not addressed by this > patch-set). > > The main issue that the patches deal with is the fact that the fixmap > PTEs that are used for patching are available for access from other > cores and might be exploited. They are not even flushed from the TLB in > remote cores, so the risk is even higher. Address this issue by > introducing a temporary mm that is only used during patching. > Unfortunately, due to init ordering, fixmap is still used during > boot-time patching. Future patches can eliminate the need for it. > Remind me; why are we doing it like this instead of fixing fixmap? Because while this fixes the text_poke crud, it does leave fixmap broken.
