vtask_enq() published a task onto the shared dispatch queue via
dataq_enq() before finishing its own initialization (task->owner) -- a
concurrent vcpu could dequeue, run, and free the task before the
producer's own write executed, an ASAN-confirmed UAF that crashed 2 of
3 controllers under a heavy burst-array-job HA workload. Moved
task->owner = vtaskmgr before the publish, mirroring the endpoint_ref-
before-publish discipline already established two lines above it
(bug-1298). Adds a stress-test regression guard (test_vtask_enq_race.c).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019QxaSzHRB7pmYFp4cVnwkA
