CVE-2025-40048

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

uio_hv_generic: Let userspace take care of interrupt mask

Remove the logic to set interrupt mask by default in uio_hv_generic

driver as the interrupt mask value is supposed to be controlled

completely by the user space. If the mask bit gets changed

by the driver, concurrently with user mode operating on the ring,

the mask bit may be set when it is supposed to be clear, and the

user-mode driver will miss an interrupt which will cause a hang.

For eg- when the driver sets inbound ring buffer interrupt mask to 1,

the host does not interrupt the guest on the UIO VMBus channel.

However, setting the mask does not prevent the host from putting a

message in the inbound ring buffer. So let’s assume that happens,

the host puts a message into the ring buffer but does not interrupt.

Subsequently, the user space code in the guest sets the inbound ring

buffer interrupt mask to 0, saying “Hey, I’m ready for interrupts”.

User space

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References