Copilot commented on code in PR #3861:
URL: https://github.com/apache/avro/pull/3861#discussion_r3567637143
##########
lang/py/avro/io.py:
##########
@@ -832,24 +1054,43 @@ def read_map(self, writers_schema:
avro.schema.MapSchema, readers_schema: avro.s
The actual count in this case
is the absolute value of the count written.
"""
- read_items = {}
+ read_items: Dict[str, object] = {}
+ # Map keys are strings (>= 1 byte length prefix) plus the value.
+ min_bytes = 1 + _min_bytes_per_element(writers_schema.values)
+ zero_byte_limit, structural_limit = _collection_limits()
+ # Track decoded pairs separately: len(read_items) counts unique keys,
so
+ # duplicate keys (later entries overwrite earlier ones) would
undercount
+ # and let a multi-block map exceed the cumulative caps.
+ items_read = 0
block_count = decoder.read_long()
while block_count != 0:
if block_count < 0:
block_count = -block_count
decoder.skip_long()
Review Comment:
Same as `read_array()`: the negative-count map block byte-size is currently
skipped with `decoder.skip_long()`, which lacks the 10-byte/64-bit varint
validation in `read_long()`. Reading it with `read_long()` (and discarding the
value) ensures malformed overlong encodings are rejected rather than looped
over.
##########
lang/py/avro/io.py:
##########
@@ -795,23 +981,59 @@ def read_array(self, writers_schema:
avro.schema.ArraySchema, readers_schema: av
The actual count in this case
is the absolute value of the count written.
"""
- read_items = []
+ read_items: List[object] = []
+ min_bytes = _min_bytes_per_element(writers_schema.items)
+ zero_byte_limit, structural_limit = _collection_limits()
block_count = decoder.read_long()
while block_count != 0:
if block_count < 0:
block_count = -block_count
decoder.skip_long()
Review Comment:
In the negative-block-count path, the block byte-size is consumed via
`decoder.skip_long()`, which does not enforce the new 10-byte/64-bit varint
bounds from `read_long()`. A malformed overlong varint here can cause excessive
looping/CPU and also bypasses strict encoding validation. Prefer consuming the
value with `read_long()` (and ignore it) so malformed encodings are rejected
consistently.
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