On Wed, Apr 6, 2016 at 1:56 PM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Wed, Apr 6, 2016 at 1:17 PM, Pavel Machek <pavel@xxxxxxx> wrote: >> >> Why is kASLR incompatible with hibernation? We can hibernate have >> 4.3 kernel resume hibernation image of 4.2 kernel (on x86-64, and I >> have patches for x86). Resuming kernel with different randomization >> does not look that much different... > > Oh, I'd absolutely prefer to just allow kaslr together with > hibernation if it actually works. > > Could the people who piped up to say that they actually use > hibernation just try passing in the "kaslr" command line option on > their machine, and see if it works for them? We could just remove the > "no kaslr with hibername" code - or at least limit it to 32-bit for > now.. > > Because that would be lovely. This is where our original investigation of having them coexist ended: https://lkml.org/lkml/2014/6/15/180 To quote Rafael Wysocki: > We're jumping from the boot kernel into the image kernel. The virtual address > comes from the image kernel, but the boot kernel has to use it. The only way > we can ensure that we'll jump to the right place is to pass the physical address > in the header (otherwise we de facto assume that the virtual address of the > target page frame will be the same in both the boot and the image kernels). > > The missing piece is that the code in swsusp_arch_resume() sets up temporary > page tables to ensure that they won't be overwritten while copying the last > remaining image kernel pages to the right page frames (those page tables > have to be stored in page frames that are free from the kernel image perspective). > > But if the kernel address space is randomized, set_up_temporary_mappings() > really should duplicate the existing layout instead of creating a new one from > scratch. Otherwise, virtual addresses before set_up_temporary_mappings() may > be different from the ones after it. -Kees -- Kees Cook Chrome OS & Brillo Security -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
