CVE-2025-21854

/// Technical description

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

sockmap, vsock: For connectible sockets allow only connected

sockmap expects all vsocks to have a transport assigned, which is expressed

in vsock_proto::psock_update_sk_prot(). However, there is an edge case

where an unconnected (connectible) socket may lose its previously assigned

transport. This is handled with a NULL check in the vsock/BPF recv path.

Another design detail is that listening vsocks are not supposed to have any

transport assigned at all. Which implies they are not supported by the

sockmap. But this is complicated by the fact that a socket, before

switching to TCP_LISTEN, may have had some transport assigned during a

failed connect() attempt. Hence, we may end up with a listening vsock in a

sockmap, which blows up quickly:

KASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127]

CPU: 7 UID: 0 PID: 56 Comm: kworker/7:0 Not tainted 6.14.0-rc1+

Workqueue: vsock-loopback vsock_loopback_wor

/// 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