ASA-2019-00086 – Linux kernel: Potential use-after-free via kvm_ioctl_create_device()

A use-after-free vulnerability was found in the way the Linux kernel's KVM hypervisor implements its device control API. While creating a device via kvm_ioctl_create_device(), the device holds a reference to a VM object, later this reference is transferred to the caller's file descriptor table. If such file descriptor was to be closed, reference count to the VM object could become zero, potentially leading to a use-after-free issue. A user/process could use this flaw to crash the guest VM resulting in a denial of service issue or, potentially, gain privileged access to a system.

ASA-2019-00085 – Linux kernel: Uninitialized memory leak in kvm_inject_page_fault()

An information leakage issue was found in the way Linux kernel's KVM hypervisor handled page fault exceptions while emulating instructions like VMXON, VMCLEAR, VMPTRLD, and VMWRITE with memory address as an operand. It occurs if the operand is a MMIO address, as the returned exception object holds uninitialized stack memory contents. A guest user/process could use this flaw to leak host's stack memory contents to a guest.