Is python buffer overflow proof?

sturlamolden sturlamolden at
Mon Aug 3 23:04:53 CEST 2009

On 2 Aug, 15:50, Jizzai <jiz... at> wrote:

> Is a _pure_ python program buffer overflow proof?
> For example in C++ you can declare a char[9] to hold user input.
> If the user inputs 10+ chars a buffer overflow occurs.

Short answer: NO

Bounds checking on sequence types is a protection against buffer
overflow, but is certainly not sufficient.

The Python interpreter is written in C. Python extension modules are
written in C (or something similar). If you find an unprotected buffer
in this C code, you can possibly overflow this buffer. This can be
used for nasty things like corrupting the stack and injecting
malicious code. There is a reason why the Python sandbox (rexec and
Bastion modules) was disabled in Python 2.3.

IronPython and Jython provides better protection against buffer
overflow than CPython, as these interpreters are written in safer
languages (C# and Java). You thus get an extra layer of protection
between the Python code and the unsafe C (used in JVM and .NET

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