On 13.11.19 17:05, Marc Zyngier wrote:
> On a system without KVM_COMPAT, we prevent IOCTLs from being issued
> by a compat task. Although this prevents most silly things from
> happening, it can still confuse a 32bit userspace that is able
> to open the kvm device (the qemu test suite seems to be pretty
> mad with this behaviour).
>
> Take a more radical approach and return a -ENODEV to the compat
> task.
>
> Reported-by: Peter Maydell <peter.maydell@xxxxxxxxxx>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> virt/kvm/kvm_main.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 543024c7a87f..1243e48dc717 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -122,7 +122,13 @@ static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
> #else
> static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl,
> unsigned long arg) { return -EINVAL; }
> -#define KVM_COMPAT(c) .compat_ioctl = kvm_no_compat_ioctl
> +
> +static int kvm_no_compat_open(struct inode *inode, struct file *file)
> +{
> + return is_compat_task() ? -ENODEV : 0;
> +}
> +#define KVM_COMPAT(c) .compat_ioctl = kvm_no_compat_ioctl, \
Do we still need compat_ioctl if open never succeeds?
> + .open = kvm_no_compat_open
> #endif
> static int hardware_enable_all(void);
> static void hardware_disable_all(void);
>
