[New-bugs-announce] [issue21213] Memory bomb by incorrect custom serializer to json.dumps

[saaj]

New submission from saaj:

I was chaning an implementation of the function that is passed to json.dumps to extend serializable types. By a mistake (**return** instead of **raise**) it turned into, which at its minum can be expressed as::

  def d(obj):
    return TypeError(repr(obj))

  json.dumps(1j, default = d) 

After a few moments by laptop froze, though after a minute I could open shell in separate session, and top command showed that python interpretter is consuming about 4GiB of memory and 50% of 4 logical cores. 

Worst about it it doesn't end with any exception, it just keeps running. Without ``repr`` it ends up with somewhat expected ``RuntimeError: maximum recursion depth exceeded while getting the str of an object``.

The same behaviour is on python3, where it just consumes memory with less speed.

OS:
Linux Mint 15 Olivia
Linux 3.8.0-31-generic #46-Ubuntu SMP Tue Sep 10 20:03:44 UTC 2013 x86_64

Packages are last available:
python  2.7.4-0ubuntu1
python3 3.3.1-0ubuntu1

P.S. Sorry for confirming on console at python.org.

----------
components: Library (Lib)
messages: 216071
nosy: saaj
priority: normal
severity: normal
status: open
title: Memory bomb by incorrect custom serializer to json.dumps
versions: Python 2.7, Python 3.3

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21213>
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