The three high-severity defects from the round-1 sweep of pf-inject /
pf-zerocopy / pf-capture (adjudicated against source — all 7 reported criticals
in these crates downgraded; these were the real highs).
- pf-inject steam_gadget: `SteamDeckGadget::drop` set `running=false` then joined
the control thread, which spends steady state parked in a blocking, no-timeout
`EVENT_FETCH` ioctl that only tests `running` at its loop top. The flag never
reaches it, closing the fd can't wake an in-flight ioctl (the syscall holds a
file reference, and the fd is shared via Arc by the very threads being joined),
so the join hung — and it runs on the session input thread via
`PadSlots::sweep`, driven by the client's `active_mask`, so a remote peer
clearing its pad bit could freeze all session input. Now wakes the parked
threads with SIGUSR1 (no-op, non-SA_RESTART handler → the ioctl returns EINTR
and the loop exits), retried until each reports done and bounded (~1s).
- pf-zerocopy cuda: the GL→CUDA "sync point" was never established for the copy.
`cuGraphicsMapResources`/`UnmapResources` were issued on the NULL stream, but
the D2D copy runs on `copy_stream()`, a `CU_STREAM_NON_BLOCKING` stream exempt
from implicit NULL-stream ordering — and the GL de-tile/CSC that produced the
texture ends with only `glFlush` (no fence). So the copy could race ahead of
the not-yet-retired GL draw: intermittent stale/torn frames under GPU load, on
the default NVIDIA capture→encode path. Map, copy, and unmap now share
`copy_stream()`, so map's device-side guarantee orders the GL work before the
copy. Zero-copy preserved (no GPU→CPU→GPU roundtrip).
- pf-capture cursor meta: `update_cursor_meta` trusted three producer-written
fields (bitmap_offset, pixel offset, stride) with no bound against the metadata
region, driving OOB pointer arithmetic and an oversized `from_raw_parts` — an
OOB read that SIGSEGVs inside the PipeWire `.process` callback (uncatchable by
the surrounding `catch_unwind`). Switched to `spa_buffer_find_meta` to obtain
the region's real `size` and validate every offset with checked arithmetic
before each deref/slice, mirroring the fd-length guard the main frame path
already applies.
Compile + existing tests green on Linux .21 (real RTX 5070 Ti): pf-inject 74/0,
pf-zerocopy 17/0, pf-capture 1/0. The gadget deadlock path only executes on a
SteamOS host with raw_gadget/dummy_hcd (not reproducible on the CachyOS box), so
that fix is reasoned + compile-verified, not runtime-exercised.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
enricobuehler
986402f731