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fix(assets): bound what the run pays, not what the document claims (0.10.1)

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A second independent review read `230d1cb` -- the commit that closed the
`v0.10.0` review's two MAJOR findings -- and found one of them open. The
bound read `/Width` and `/Height`, which an untrusted document writes, while
`get_data()` pays for the stream beside them; `/Length` is the COMPRESSED
length and the two numbers are independent.

Re-measured here on `ed8d9d7` before anything changed, in its own
interpreter: a 408 516-byte PDF declaring 1x1 and carrying 400 MB of deflated
zeros was CARRIED, no rejection, 891 904 000 B peak RSS. After: 0 carried,
`asset_too_large`, 57 065 472 B. At 1,2 GB of zeros, 2 436 MB -> 64 569 344 B
-- the cost no longer scales with the bomb. End to end through the CLI with
the shipped defaults: 838 000 640 B and an asset written -> exit 0,
79 650 816 B, `0 carried of 1 found`, no `assets/`.

Three numbers are bounded now, not one: what a container DECLARES, what a
carried FILE measures (`read_image`, so a 49 MP PNG of 47 705 bytes is not
passed on to a consumer), and what a PDF stream DECOMPRESSES to
(`assets.inflated_size`, a chunk at a time, output discarded, before
`get_data()`). The limit is stated rather than implied: the stream
measurement runs where `FlateDecode` is the first filter and the document is
not encrypted; every other chain is a check on the decoded length AFTER the
decode, a counted refusal and not a bounded one.

A non-positive declared dimension is `asset_size_invalid`, its own code,
raised before the stream is read. `-1 x 40000000000` is a NEGATIVE pixel
count, under which every `>` bound read as satisfied, so the check returned
silently and the refusal arrived from `encode_png` as
`asset_samples_invalid`. Its own code because a publisher shipping a picture
bigger than this package carries and a dictionary written to be read wrong
are different facts about a document.

Two smaller findings in the line that says what is missing, both introduced
by the first fix: the address was written twice, once bare, and a linkifying
renderer autolinks a bare URL -- written once now, in one code span; and
`label` became a dead parameter, so the figure's caption was dropped, a
regression against 0.10.0. It is written again in the `-- <label>` form a
carried pointer uses.

Version bumped to 0.10.1 across all ten places. Nine were unbound and stale:
four README install lines naming the previous release, two prose lines, the
"current tag" entry, `uv.lock`, and a CHANGELOG whose 0.10.1 content sat
under `[Unreleased]`. Two new packaging tests bind them to `__version__`, and
the README's guard tag to `[tool.uv.sources]`.

Every test was red first. The fate of every image is identical with and
without the new bound on three K2 PDFs carrying 800 images (464/464, 311/311
with the same 12 rejections, 25/25), and the second inflate is below the
noise floor there. 0 shipped artifacts move: no bundle under `examples/`,
`skills/` or `tests/fixtures/` carries an image pointer at all, measured
against a known-positive control.

`asset_too_large` was undocumented in the error registry; both codes are
there now. `tools/okf_accounting_gate.py` gains the new code in its closed
list -- one string, no behaviour change, stated because that file belongs to
another order.

Suite 2141 passed / 1 skipped, ruff + format + mypy --strict clean.
Report: docs/2026-09-18-bildestien-holder-0-10-1.md

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
Kjell Tore Guttormsen 2026-09-18 13:41:18 +02:00
commit 0f308c1f56
Signed by: ktg
SSH key fingerprint: SHA256:JakMjO6FTBBzN0Bhfj9saOoEjaFxlSdYuZQQpM/lF9Q
15 changed files with 842 additions and 81 deletions
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142
src/llm_ingestion_okf/assets.py
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@ -131,22 +131,50 @@ IMAGE_POINTER = re.compile(
#: Found by an independent review of 0.10.0 before it was pushed.
MAX_IMAGE_PIXELS = 40_000_000
#: The same bound in bytes, for a payload whose pixels are not yet known (an
#: inline `data:` URI) and for raw samples with several channels.
#: The same bound in bytes: for a payload whose pixels are not yet known (an
#: inline `data:` URI) and for the DECOMPRESSED size of a stream, which is a
#: different number from anything the container declares. `/Length` in a PDF
#: image dictionary is the COMPRESSED length and `/Width` and `/Height` are a
#: claim; nothing in the dictionary states what the decompression will cost.
MAX_IMAGE_BYTES = 256 * 1024 * 1024
#: How much of a stream is inflated at a time while `inflated_size` measures
#: it. The cap on the OUTPUT is what keeps the measurement cheaper than the
#: bomb; the input is handed over whole because it is already in memory.
_INFLATE_CHUNK = 1 << 20
def check_size(
width: int | None, height: int | None, *, name: str, channels: int = 1, bits: int = 8
) -> None:
"""Refuse a declared size beyond the bound, BEFORE anything is decoded.
Read off what the container DECLARES, which is the only number available
before the cost is paid: a check after the decompression has already paid
for the bomb it was meant to stop.
Read off what the container DECLARES. That is the only number available
before a cost is paid, and it is a CLAIM by an untrusted document rather
than a measurement: this refuses a picture too large to be one we carry,
and it says nothing about what decompressing the stream beside it costs.
`inflated_size` is the other half, and neither substitutes for the other.
`None` is UNKNOWN -- a container that declares no size leaves nothing to
bound, and inventing a number would refuse a legitimate picture. A size
that is declared and is not positive is neither unknown nor large: it is a
dictionary that was written wrong or written to be read wrong, and it is
refused here rather than three steps later by the encoder. Measured on
`230d1cb`: `/Width -1 /Height 40000000000` multiplies to a NEGATIVE pixel
count, so every `>` below was false, the function returned silently, 400 MB
was decompressed, and the refusal arrived from `encode_png` under
`asset_samples_invalid` -- a code about a sample buffer for a defect in the
declaration.
"""
if not width or not height:
if width is None or height is None:
return
if width <= 0 or height <= 0:
raise ExtractionError(
f"the image {name!r} declares {width}x{height}, which is not a size; "
"refused unread rather than multiplied out, because a non-positive "
"dimension makes every bound below it read as satisfied",
code="asset_size_invalid",
)
pixels = width * height
expected = pixels * channels * (bits // 8 or 1)
if pixels > MAX_IMAGE_PIXELS or expected > MAX_IMAGE_BYTES:
@ -169,6 +197,53 @@ def check_payload(size: int, *, name: str) -> None:
)
def inflated_size(raw: bytes, *, name: str, limit: int | None = None) -> int:
"""What a deflate stream costs to decompress, measured without paying it.
THE DECLARED SIZE AND THE COST ARE TWO INDEPENDENT NUMBERS, and binding
only the first is what an independent review of 0.10.1 measured on
`230d1cb`: a 408 516-byte PDF declaring a 1x1 picture and carrying 400 MB
of deflated zeros was CARRIED, with no rejection, at 892 MB of peak RSS --
about 2 100x the file size, linear, so a 10 MB document is ~21 GB and takes
the whole batch build with it. `check_size` was reading a claim as though
it were a cost.
The output is inflated a chunk at a time and DISCARDED: only the running
total is kept, so the measurement stays bounded whatever the stream holds,
and it stops at the first chunk that crosses `limit`. A legitimate image is
therefore inflated twice -- once here and once by the reader that carries
it -- which is the price of not holding an unbounded buffer to find out how
big it is. Measured on R761 Prosesskoden:2025 (50 image objects): the
second pass costs under a second of a 200-second extraction.
A stream that is not valid deflate data is not this function's problem: the
reader behind it reports that in its own vocabulary, so a `zlib.error` ends
the measurement at whatever was produced up to it.
"""
bound = MAX_IMAGE_BYTES if limit is None else limit
decompressor = zlib.decompressobj()
total = 0
pending = raw
try:
while True:
produced = decompressor.decompress(pending, _INFLATE_CHUNK)
total += len(produced)
if total > bound:
raise ExtractionError(
f"the stream behind {name!r} decompresses to more than {bound} "
f"bytes from {len(raw)} bytes of input, over this package's "
"bound; refused without being held, because the size a "
"container declares is a claim and this is the cost",
code="asset_too_large",
)
pending = decompressor.unconsumed_tail
if decompressor.eof or not pending:
break
except zlib.error:
return total
return total
@dataclass(frozen=True)
class ExtractedImage:
"""One image a document carries, as this package will write it.
@ -310,6 +385,16 @@ def read_image(data: bytes, *, name: str, label: str | None = None) -> Extracted
)
media_type, suffix = kind
size = dimensions(data)
# THE BOUND HOLDS FOR A FILE CARRIED VERBATIM TOO. This package does not
# decode one, so it pays nothing for it -- but writing a 7 000 x 7 000 PNG
# of 47 705 bytes into a bundle hands the consumer the same bomb with
# `7000x7000 px` printed beside it, and the README's first sentence about
# this bound says such an image is refused. Sniffed from the header rather
# than claimed, like the type beside it. Measured: the largest of the
# 4 828 objects in the reference corpus is 18.6 MP, so nothing anyone has
# measured is refused here.
if size is not None:
check_size(size[0], size[1], name=name)
return ExtractedImage(
data=data,
name=name,
@ -527,22 +612,37 @@ def render_missing(
absence they were never shown -- which is precisely the shape of the defect
this whole capability exists to close.
The href is kept when the source had one and it survives the link grammar,
so a remote figure says WHERE it was. Extraction never opens a socket: the
network gate is an explicit per-run opt-in and extraction is not on that
path, so a remote source is carried as a name and never as bytes.
The href is kept when the source had one, so a remote figure says WHERE it
was. Extraction never opens a socket: the network gate is an explicit
per-run opt-in and extraction is not on that path, so a remote source is
carried as a name and never as bytes.
`label` is the alt text or the figure caption, and it is written for the
same reason the line exists at all: the reader deciding whether the missing
picture mattered is much better served by "Figur 84-1 Tverrprofil" than by
a file name. 0.10.1 dropped it while closing the live-link defect -- the
parameter stayed in the signature and no branch read it -- which an
independent review measured as a regression against 0.10.0.
"""
shown = _inline(name or "image")
detail = f"Image: {shown} (not carried: {_inline(reason)})"
# INERT, never `![..](href)`. A remote reference is an address the
# document's author chose, and 0.10.0 wrote it as a live markdown image: a
# consumer that renders the bundle, or an agent that fetches what it
# renders, turns "this bundle was opened" into a beacon to them -- and a
# server-side consumer into an SSRF. This package opens no socket, which is
# not the same as the pointer being harmless.
#
# The address is STATED, because a reader has to know what stood there --
# and stated ONCE, inside a code span. 0.10.1 wrote it twice: once in the
# span and once as the bare `name`, and a GFM/linkify renderer autolinks a
# bare URL into `<a href="...">`. It takes a click rather than a render, so
# it is weaker than `![..]()` -- but "inert" was half the truth, and half
# is what this line exists not to be.
if href:
# INERT, never `![..](href)`. A remote reference is an address the
# document's author chose, and 0.10.0 wrote it as a live markdown
# image: a consumer that renders the bundle, or an agent that fetches
# what it renders, turns "this bundle was opened" into a beacon to
# them -- and a server-side consumer into an SSRF. This package opens
# no socket, which is not the same as the pointer being harmless.
# The address is still STATED, in a code span, because a reader has to
# know what stood there to judge whether the picture mattered.
address = _inline(href).replace("`", "'")
return f"{detail} address: `{address}`"
shown = f"`{address}`"
else:
shown = _inline(name or "image")
detail = f"Image: {shown} (not carried: {_inline(reason)})"
if label:
detail += f" -- {_inline(label)}"
return detail