Mark Rutland recently pointed out that a couple of issues with the way we deal with compat tasks: 1) arm64 unexpectedly selects KVM_COMPAT, while offering no way for a 32bit userspace to change any register 2) Even deselecting KVM_COMPAT, we end-up with compat_ioctl being NULL, and the VFS behaviour is thus to call the non-compat ioctl (1) is completely unintentional and should be fixed. (2) is quite odd, and probably just as unintentional. This series fixes it by installing a compat_ioctl callback whose only job is to return -EINVAL. Tested on arm64 with a 32bit kvmtool. Marc Zyngier (2): KVM: Enforce error in ioctl for compat tasks when !KVM_COMPAT KVM: arm64: Prevent KVM_COMPAT from being selected virt/kvm/Kconfig | 2 +- virt/kvm/kvm_main.c | 19 +++++++++---------- 2 files changed, 10 insertions(+), 11 deletions(-) -- 2.17.1
