[PD-dev] [ pure-data-Bugs-3298383 ] PureData writing beyond t_object struct on Windows.

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Bugs item #3298383, was opened at 2011-05-06 14:13
Message generated for change (Tracker Item Submitted) made by radarsat1
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Category: puredata
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Stephen Sinclair (radarsat1)
Assigned to: Nobody/Anonymous (nobody)
Summary: PureData writing beyond t_object struct on Windows.

Initial Comment:
This very simple external provides a responder to a single message, "test".  The object's data structure extends t_object by a single integer, "pad".  I set "pad" to zero immediately after pd_new().  Later, when it receives "test", it prints "pad" again.  On Linux, the log contains the following:

hello_new, x->pad: 0
hello_test, x->pad: 0

However, on Windows, the log contains this:

hello_new, x->pad: 0
hello_test, x->pad: 0x1

This means somewhere between initializing my object and receiving "test", the t_object structure is written to beyond its length.

This was noticed because in a real object I had a pointer in that location, which was invalidated by this effect, and dereferencing it caused PureData to crash.  My temporary solution is to put a padding int there, but it would be nice to find the problem.  I haven't yet managed to compile Pd from scratch for Windows yet, so I can't debug it until I get that working, but I thought I should report it in case anyone knows more.

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