On Wed, Mar 8, 2017 at 3:55 PM, Laura Abbott <labb...@redhat.com> wrote: > On 03/08/2017 02:36 PM, Kees Cook wrote: >> On Wed, Mar 8, 2017 at 2:27 PM, Daniel Borkmann <dan...@iogearbox.net> wrote: >>> [ 28.474232] rodata_test: test data was not read only >>> [...] >> >> In my tests so far, I've never been able to get rodata_test to fail >> (Qemu 2.5.0, Ubuntu). I'll retry with your .config and see if I can >> recheck under Qemu 2.7.1. Do you see these failures on real hardware? >> >> -Kees >> > > FWIW, I'm seeing the same issue with qemu 2.6.2 and 2.8.0 on Fedora 24 > and rawhide respectively. > > I also notice that CONFIG_X86_PAE is turned off in the defconfig. If > I set CONFIG_HIGHMEM_64G which turns on CONFIG_X86_PAE the problem > goes away. I can't tell if this is an indication of magically hiding > the TLB problem or if there is an issue with !X86_PAE invalidation.
I found my difference. I normally run qemu with "-cpu host" which makes the failure go away. With "-cpu kvm64", I see the rodata_test failure immediately. Seems like this may be a kvm cpu feature emulation bug? I'll see if I can find the specific cpu feature in the morning... -Kees -- Kees Cook Pixel Security
