Commit b9876e6d authored Nov 13, 2019 by Marc Zyngier Committed by Paolo Bonzini Nov 13, 2019

KVM: Forbid /dev/kvm being opened by a compat task when CONFIG_KVM_COMPAT=n



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@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 6cbee2b9

virt/kvm/kvm_main.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -124,7 +124,13 @@ 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);

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