CVE-2026-68429

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

drm/dp_mst: Handle torn-down topology gracefully in drm_dp_mst_topology_queue_probe()

A hotplug or link-loss event can tear down the MST topology

(setting mgr->mst_state = false and mgr->mst_primary = NULL) concurrently

with a caller invoking drm_dp_mst_topology_queue_probe(). Since the check

is already performed under mgr->lock, the condition is not a programming

error but a valid race -- the topology was valid when the caller decided

to call this function, but was torn down before the lock was acquired.

Replace the drm_WARN_ON() with a graceful early return. This eliminates

spurious kernel warnings and the resulting compositor crashes observed

when connecting/disconnecting DP MST monitors, while keeping the correct

behavior of doing nothing when MST is not active. A drm_dbg_mst() trace

is added so the skipped probe remains observable under MST debug logging.

The existing WARN_ON(mgr->mst_primary) in drm_dp_mst_topology_mgr_set_mst()

already catches the case where the topology is initialized twice, so no

diagnostic coverage is lost.