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bflatastic
991ce2c635
hayro (0.7.2 and 0.8.0 alike) inflates Flate and LZW data with no ceiling, so a few megabytes
of zeros ask for gigabytes, and applies a predictor before checking its parameters: Columns 0
divides by zero (a panic, an abort on the web), a huge Columns allocates a row that large (an
abort everywhere). Both happen inside the reader, before any of our limits.
A file is refused ("a stream in it would decode to more than 256 MB, or its decode parameters
can't be applied") when a stream's decode parameters ask for a predictor the reader can't apply,
or when it decodes past 256 MB through Flate, LZW, run-length and the ASCII encodings before
them, decoded here with a ceiling (only streams large enough to get there are decoded). Every
object's stream is looked at once the file is open (decrypted, references followed), with the
inline images of anything that can be content; object and cross-reference streams, which the
reader decodes while it opens the file, are looked at first in the file's text.