From b9876e6de123adb52ac693bac08c493e989bd93e Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Wed, 13 Nov 2019 16:05:23 +0000 Subject: 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 Signed-off-by: Marc Zyngier Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'virt/kvm/kvm_main.c') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 524cff24a68d..6a65ed915c7a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -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); -- cgit v1.2.3-59-g8ed1b