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fix: prevent PyNvVideoCodec decoder slot limit bypass via ClassVar shadowing (#52126)

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Signed-off-by: jperezde <jperezde@redhat.com>
This commit is contained in:
Juan Pérez de Algaba
2026-08-17 17:45:40 +00:00
committed by GitHub
parent cfbc5afbf7
commit ceb340e2eb
2 changed files with 151 additions and 82 deletions
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tests/multimodal/test_video.py
+107 -56
View File
@@ -24,12 +24,14 @@ from vllm.multimodal.video import (
Molmo2VideoBackend,
PyNvVideoCodecDecoderSlot,
PyNvVideoCodecVideoBackend,
PyNvVideoCodecVideoBackendMixin,
Qwen2VLVideoBackend,
Qwen3VLVideoBackend,
VideoBackend,
VideoLoader,
VideoSourceMetadata,
VideoTargetMetadata,
_pynv_decoder_pool,
get_video_loader_backend_for_processor,
)
from vllm.platforms import current_platform
@@ -47,6 +49,27 @@ FAKE_OUTPUT_1 = np.random.rand(NUM_FRAMES, 1280, 720, 3)
FAKE_OUTPUT_2 = np.random.rand(NUM_FRAMES, 1280, 720, 3)
@contextmanager
def _fresh_decoder_pool():
"""Reset module-level decoder pool for isolated test runs."""
pool = _pynv_decoder_pool
old_slots = pool.slots
old_active = pool.active
old_cond = pool.cond
old_max = pool.max_slots
pool.slots = []
pool.active = 0
pool.cond = threading.Condition()
pool.max_slots = None
try:
yield pool
finally:
pool.slots = old_slots
pool.active = old_active
pool.cond = old_cond
pool.max_slots = old_max
@VIDEO_LOADER_REGISTRY.register("test_video_loader_1")
class TestVideoLoader1(VideoLoader):
@classmethod
@@ -206,16 +229,7 @@ def test_pynvvideocodec_corrupted_videos_raise_value_error():
corrupted_video = (ASSETS_DIR / "corrupted.mp4").read_bytes()
malformed_video = corrupted_video[:128]
old_slots = PyNvVideoCodecVideoBackend._decoder_slots
old_active_slots = PyNvVideoCodecVideoBackend._active_decoder_slots
old_cond = PyNvVideoCodecVideoBackend._decoder_slot_cond
old_max_slots = PyNvVideoCodecVideoBackend._max_decoder_slots
try:
PyNvVideoCodecVideoBackend._decoder_slots = []
PyNvVideoCodecVideoBackend._active_decoder_slots = 0
PyNvVideoCodecVideoBackend._decoder_slot_cond = threading.Condition()
PyNvVideoCodecVideoBackend._max_decoder_slots = None
with _fresh_decoder_pool():
loader = VIDEO_LOADER_REGISTRY.load(PYNVVIDEOCODEC_VIDEO_BACKEND)
with pytest.raises(
ValueError,
@@ -247,11 +261,6 @@ def test_pynvvideocodec_corrupted_videos_raise_value_error():
hw_decoders=1,
)
assert frames.shape[0] == 1
finally:
PyNvVideoCodecVideoBackend._decoder_slots = old_slots
PyNvVideoCodecVideoBackend._active_decoder_slots = old_active_slots
PyNvVideoCodecVideoBackend._decoder_slot_cond = old_cond
PyNvVideoCodecVideoBackend._max_decoder_slots = old_max_slots
@pytest.mark.parametrize("hw_decoders", [1, 3])
@@ -263,15 +272,7 @@ def test_pynvvideocodec_decoder_slots_are_bounded(
pass
create_count = 0
old_slots = PyNvVideoCodecVideoBackend._decoder_slots
old_active_slots = PyNvVideoCodecVideoBackend._active_decoder_slots
old_cond = PyNvVideoCodecVideoBackend._decoder_slot_cond
old_max_slots = PyNvVideoCodecVideoBackend._max_decoder_slots
try:
PyNvVideoCodecVideoBackend._decoder_slots = []
PyNvVideoCodecVideoBackend._active_decoder_slots = 0
PyNvVideoCodecVideoBackend._decoder_slot_cond = threading.Condition()
PyNvVideoCodecVideoBackend._max_decoder_slots = None
with _fresh_decoder_pool():
PyNvVideoCodecVideoBackend._configure_decoder_slots(hw_decoders)
def fake_create_slot(cls):
@@ -309,17 +310,12 @@ def test_pynvvideocodec_decoder_slots_are_bounded(
assert seen_slots[0] in retained_slots
assert create_count == hw_decoders
finally:
PyNvVideoCodecVideoBackend._decoder_slots = old_slots
PyNvVideoCodecVideoBackend._active_decoder_slots = old_active_slots
PyNvVideoCodecVideoBackend._decoder_slot_cond = old_cond
PyNvVideoCodecVideoBackend._max_decoder_slots = old_max_slots
def test_pynvvideocodec_decoder_slots_are_configured_once(
monkeypatch: pytest.MonkeyPatch,
):
monkeypatch.setattr(PyNvVideoCodecVideoBackend, "_max_decoder_slots", None)
monkeypatch.setattr(_pynv_decoder_pool, "max_slots", None)
PyNvVideoCodecVideoBackend._configure_decoder_slots(2)
PyNvVideoCodecVideoBackend._configure_decoder_slots(2)
@@ -358,15 +354,16 @@ def test_pynvvideocodec_failed_rebuild_invalidates_decoder_slot():
assert slot.source_path is None
raise RuntimeError("construct failed")
old_slots = PyNvVideoCodecVideoBackend._decoder_slots
old_active_slots = PyNvVideoCodecVideoBackend._active_decoder_slots
old_cond = PyNvVideoCodecVideoBackend._decoder_slot_cond
old_max_slots = PyNvVideoCodecVideoBackend._max_decoder_slots
pool = _pynv_decoder_pool
old_slots = pool.slots
old_active = pool.active
old_cond = pool.cond
old_max = pool.max_slots
try:
PyNvVideoCodecVideoBackend._decoder_slots = [slot]
PyNvVideoCodecVideoBackend._active_decoder_slots = 1
PyNvVideoCodecVideoBackend._decoder_slot_cond = threading.Condition()
PyNvVideoCodecVideoBackend._max_decoder_slots = 1
pool.slots = [slot]
pool.active = 1
pool.cond = threading.Condition()
pool.max_slots = 1
with (
pytest.raises(RuntimeError, match="construct failed"),
@@ -386,12 +383,12 @@ def test_pynvvideocodec_failed_rebuild_invalidates_decoder_slot():
assert old_decoder.poisoned
assert slot.decoder is None
assert slot.source_path is None
assert PyNvVideoCodecVideoBackend._decoder_slots == [slot]
assert pool.slots == [slot]
finally:
PyNvVideoCodecVideoBackend._decoder_slots = old_slots
PyNvVideoCodecVideoBackend._active_decoder_slots = old_active_slots
PyNvVideoCodecVideoBackend._decoder_slot_cond = old_cond
PyNvVideoCodecVideoBackend._max_decoder_slots = old_max_slots
pool.slots = old_slots
pool.active = old_active
pool.cond = old_cond
pool.max_slots = old_max
@pytest.mark.skipif(not current_platform.is_cuda(), reason="Requires CUDA")
@@ -405,15 +402,15 @@ def test_pynvvideocodec_h200_recovers_after_unsupported_8k():
valid_video = create_long_gop_video(num_frames=2, width=64, height=64)
unsupported_video = (ASSETS_DIR / "unsupported_8k_h264.mp4").read_bytes()
old_slots = PyNvVideoCodecVideoBackend._decoder_slots
old_active_slots = PyNvVideoCodecVideoBackend._active_decoder_slots
old_cond = PyNvVideoCodecVideoBackend._decoder_slot_cond
old_max_slots = PyNvVideoCodecVideoBackend._max_decoder_slots
old_slots = _pynv_decoder_pool.slots
old_active = _pynv_decoder_pool.active
old_cond = _pynv_decoder_pool.cond
old_max = _pynv_decoder_pool.max_slots
try:
PyNvVideoCodecVideoBackend._decoder_slots = []
PyNvVideoCodecVideoBackend._active_decoder_slots = 0
PyNvVideoCodecVideoBackend._decoder_slot_cond = threading.Condition()
PyNvVideoCodecVideoBackend._max_decoder_slots = None
_pynv_decoder_pool.slots = []
_pynv_decoder_pool.active = 0
_pynv_decoder_pool.cond = threading.Condition()
_pynv_decoder_pool.max_slots = None
loader = VIDEO_LOADER_REGISTRY.load(PYNVVIDEOCODEC_VIDEO_BACKEND)
frames_before, _ = loader.load_bytes(
@@ -443,12 +440,66 @@ def test_pynvvideocodec_h200_recovers_after_unsupported_8k():
assert frames_after.shape == frames_before.shape
finally:
for slot in PyNvVideoCodecVideoBackend._decoder_slots:
for slot in _pynv_decoder_pool.slots:
slot.invalidate()
PyNvVideoCodecVideoBackend._decoder_slots = old_slots
PyNvVideoCodecVideoBackend._active_decoder_slots = old_active_slots
PyNvVideoCodecVideoBackend._decoder_slot_cond = old_cond
PyNvVideoCodecVideoBackend._max_decoder_slots = old_max_slots
_pynv_decoder_pool.slots = old_slots
_pynv_decoder_pool.active = old_active
_pynv_decoder_pool.cond = old_cond
_pynv_decoder_pool.max_slots = old_max
def test_pynvvideocodec_cross_subclass_shares_single_pool():
"""Regression test for GHSA-j682-9xp5-rrf3.
Multiple subclasses of PyNvVideoCodecVideoBackendMixin must share the
same process-wide decoder slot limit rather than getting independent
counters via ClassVar shadowing.
"""
class FakeSlot:
pass
create_count = 0
def fake_create_slot(cls):
nonlocal create_count
create_count += 1
return FakeSlot()
with _fresh_decoder_pool() as pool:
pool.max_slots = 2
orig_create = PyNvVideoCodecVideoBackendMixin._create_decoder_slot
PyNvVideoCodecVideoBackendMixin._create_decoder_slot = classmethod(
fake_create_slot
)
try:
with ExitStack() as stack:
stack.enter_context(VideoBackend._borrow_decoder_slot())
stack.enter_context(Qwen3VLVideoBackend._borrow_decoder_slot())
assert pool.active == 2
blocked = threading.Event()
acquired = threading.Event()
def try_borrow():
blocked.set()
with Qwen2VLVideoBackend._borrow_decoder_slot():
acquired.set()
t = threading.Thread(target=try_borrow)
t.start()
blocked.wait(timeout=2.0)
assert not acquired.wait(timeout=0.3)
assert acquired.wait(timeout=2.0)
t.join(timeout=2.0)
assert not t.is_alive()
assert create_count == 2
assert len(pool.slots) == 2
finally:
PyNvVideoCodecVideoBackendMixin._create_decoder_slot = orig_create
@pytest.mark.parametrize("hw_decoders", [0, -1, 1.5, True, "2"])
vllm/multimodal/video.py
+44 -26
View File
@@ -671,13 +671,38 @@ def _pynvvc_frames_to_nhwc(frames: torch.Tensor) -> torch.Tensor:
return frames.contiguous()
class _PyNvDecoderPool:
"""Process-wide singleton managing PyNvVideoCodec decoder slot state.
Prevents subclass counter shadowing (GHSA-j682-9xp5-rrf3) by storing
all mutable pool state in a single module-level instance rather than
in ClassVar attributes that get shadowed by Python's augmented
assignment semantics on subclasses.
"""
def __init__(self) -> None:
self.slots: list[PyNvVideoCodecDecoderSlot] = []
self.active: int = 0
self.cond: threading.Condition = threading.Condition()
self.max_slots: int | None = None
def configure(self, hw_decoders: int) -> None:
with self.cond:
if self.max_slots is None:
self.max_slots = hw_decoders
elif self.max_slots != hw_decoders:
raise RuntimeError(
"PyNvVideoCodec decoder count is already configured as "
f"{self.max_slots}, got {hw_decoders}"
)
_pynv_decoder_pool = _PyNvDecoderPool()
class PyNvVideoCodecVideoBackendMixin:
"""PyNvVideoCodec utilities for GPU-backed frame decode."""
_decoder_slots: ClassVar[list[PyNvVideoCodecDecoderSlot]] = []
_active_decoder_slots: ClassVar[int] = 0
_decoder_slot_cond: ClassVar[threading.Condition] = threading.Condition()
_max_decoder_slots: ClassVar[int | None] = None
_DEVICE_INDEX: ClassVar[int] = 0
@classmethod
@@ -704,14 +729,7 @@ class PyNvVideoCodecVideoBackendMixin:
@classmethod
def _configure_decoder_slots(cls, hw_decoders: object) -> None:
hw_decoders = validate_pynvvideocodec_hw_decoders(hw_decoders)
with cls._decoder_slot_cond:
if cls._max_decoder_slots is None:
cls._max_decoder_slots = hw_decoders
elif cls._max_decoder_slots != hw_decoders:
raise RuntimeError(
"PyNvVideoCodec decoder count is already configured as "
f"{cls._max_decoder_slots}, got {hw_decoders}"
)
_pynv_decoder_pool.configure(hw_decoders)
@staticmethod
@contextmanager
@@ -729,28 +747,28 @@ class PyNvVideoCodecVideoBackendMixin:
@classmethod
@contextmanager
def _borrow_decoder_slot(cls):
pool = _pynv_decoder_pool
create_slot = False
with cls._decoder_slot_cond:
max_decoder_slots = cls._max_decoder_slots
if max_decoder_slots is None:
with pool.cond:
if pool.max_slots is None:
raise RuntimeError("PyNvVideoCodec decoder slots are not configured")
while True:
if cls._decoder_slots:
slot = cls._decoder_slots.pop()
if pool.slots:
slot = pool.slots.pop()
break
if cls._active_decoder_slots < max_decoder_slots:
cls._active_decoder_slots += 1
if pool.active < pool.max_slots:
pool.active += 1
create_slot = True
break
cls._decoder_slot_cond.wait()
pool.cond.wait()
if create_slot:
try:
slot = cls._create_decoder_slot()
except Exception:
with cls._decoder_slot_cond:
cls._active_decoder_slots -= 1
cls._decoder_slot_cond.notify()
with pool.cond:
pool.active -= 1
pool.cond.notify()
raise
borrow_succeeded = False
@@ -760,9 +778,9 @@ class PyNvVideoCodecVideoBackendMixin:
finally:
if not borrow_succeeded:
slot.invalidate()
with cls._decoder_slot_cond:
cls._decoder_slots.append(slot)
cls._decoder_slot_cond.notify()
with pool.cond:
pool.slots.append(slot)
pool.cond.notify()
@staticmethod
def _metadata_value(metadata, *names: str, default=None):