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, \
+ .open = kvm_no_compat_open
#endif
static int hardware_enable_all(void);
static void hardware_disable_all(void);
--
2.20.1
