In the Linux kernel, the following vulnerability has been resolved:
drm/v3d: Associate BOs with every job that accesses them
A submission can expand into a chain of jobs (e.g. bin + render + cache
clean). Implicit synchronization in v3d_submit_lock_reservations() is gated
on each job's bo[], but the BO list was only ever attached to the last job
of the chain. When that last job is a trailing CACHE_CLEAN job, the job
that actually consumes the BOs (that is, a RENDER or CSD job) was left with
bo_count == 0 and picked up no implicit dependencies. It could therefore
be dispatched to the hardware and read a BO while another context was still
writing it, leading to data corruption.
Attach the BOs to the job that consumes them, so (1) it acquires the
correct implicit dependencies during reservation locking and (2) they are
kept mapped until the end of the submission. Give it references to all
consuming job's BOs through v3d_job_reference_bos() instead of looking the
handles up a second time; that avoids a redundant lookup and guarantees
both jobs reference the exact same objects.
As the CACHE_CLEAN job now carries a BO array as well, add a per-job
has_implicit_dep flag so that only the consuming jobs take implicit
dependencies. The CACHE_CLEAN job (a global flush) and the BIN job (binning
waiting on another context is not a realistic scenario) are excluded.