CVE-2026-63980

Technical Description

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

net/handshake: Use spin_lock_bh for hn_lock

nvmet_tcp_state_change(), a socket callback that runs in BH context,

can reach handshake_req_cancel() via nvmet_tcp_schedule_release_queue()

and tls_handshake_cancel(). handshake_req_cancel() acquires

hn->hn_lock with plain spin_lock(). If a process-context thread on

the same CPU holds hn->hn_lock when a softirq invokes the cancel path,

the lock attempt deadlocks. This is the only caller that invokes

tls_handshake_cancel() from BH context; every other consumer calls it

from process context.

Deferring the cancel to process context in the NVMe target is not

straightforward: nvmet_tcp_schedule_release_queue() must call

tls_handshake_cancel() atomically with its state transition to

DISCONNECTING. If the cancel were deferred, the handshake completion

callback could fire in the window before the cancel runs, observe the

unexpected state, and return without dropping its kref

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