gh-119342: Fix OOM vulnerability in plistlib #119343
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Reading a specially prepared small Plist file could cause OOM because file's read(n) preallocates a bytes object for reading the specified amount of data. Now plistlib reads large data by chunks, therefore the upper limit of consumed memory is proportional to the size of the input file.
serhiy-storchaka
added
type-security
picnixz
reviewed
May 22, 2024
Lib/plistlib.py
Outdated
| if len(data) != size: | ||
| raise InvalidFileException | ||
| return data | ||
| cursize = min(size, 1 << 20) |
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Do you want to perhaps make (1 << 20) as a constant the same way you did for the pickle vulnerability?
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Maybe. In the pickle module the constant is used in several places, so there are more reasons to use a named constant there.
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
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I've marked this Draft for now as discussion on this on the security response team list is not complete. (we'll summarize that in a public issue once it has settled) |
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See #119514 (comment) for results of the PSRT discussion. |
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Reading a specially prepared small Plist file could cause OOM because file's read(n) preallocates a bytes object for reading the specified amount of data. Now plistlib reads large data by chunks, therefore the upper limit of consumed memory is proportional to the size of the input file.