CVE-2026-98301

/// Technical description

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

net: bridge: mst: move switchdev call outside rcu

This is a follow-up of one of sashiko's pre-existing bug reports.

br_mst_set_state() calls switchdev_port_attr_set() for nonzero MSTIs

while holding rcu_read_lock() which invokes the blocking switchdev

notifier chain and may sleep. Nonzero MSTI changes come from netlink

with rtnl held. Move the switchdev call before entering the rcu section and

assert that rtnl is held.

The call cannot be deferred because netlink needs its error and extack.

Also DSA reads the old bridge MST state during the callback and checks it.

A deferred callback will be late and will see the updated state.

/// 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