On Tue, Jun 7, 2016 at 10:41 PM, Heiko Carstens <heiko.carst...@de.ibm.com> wrote: > On Tue, Jun 07, 2016 at 11:11:17AM -0700, Kees Cook wrote: >> On Tue, Jun 7, 2016 at 11:07 AM, Heiko Carstens >> <heiko.carst...@de.ibm.com> wrote: >> > On Tue, Jun 07, 2016 at 08:49:14AM -0700, Kees Cook wrote: >> >> > Heiko Carstens (2): >> >> > vmlinux.lds.h: allow arch specific handling of ro_after_init data >> >> > section >> >> > s390/mm: add proper __ro_after_init support >> >> > >> >> > arch/s390/include/asm/cache.h | 3 --- >> >> > arch/s390/include/asm/sections.h | 1 + >> >> > arch/s390/kernel/vmlinux.lds.S | 12 +++++++++++- >> >> > arch/s390/mm/init.c | 7 ++++--- >> >> > arch/s390/mm/vmem.c | 7 +++---- >> >> > include/asm-generic/vmlinux.lds.h | 10 +++++++++- >> >> > 6 files changed, 28 insertions(+), 12 deletions(-) >> >> >> >> Awesome! This looks great to me! Have you had a chance to look through >> >> any of the arch/s390/ __init code for variables that should be marked >> >> __ro_after_init? >> > >> > Not yet, and actually this I'm a bit reluctant to do that, since any wrong >> > annotation will lead to kernel crashes sooner or later ;) >> > However I'll look into this as well. >> >> Yup, though the good news is it's usually discovered very quickly. :) > > Eventually it might make sense to add something like > DEBUG_SECTION_MISMATCH, which would only report on _write_ accesses from > non-init sections. > > Not sure if this can be done easily and without the need of a new compiler > feature. The new problem class I'm afraid of is more or less the same that > we had when non-init code referenced (already freed) initdata objects.
Yeah. I'm hopeful we'll have a gcc plugin to help with this soon. -Kees -- Kees Cook Chrome OS & Brillo Security