realloc overflow problem

[Jason Tishler <jason at tishler dot net>]

[This may be more appropriate for the newlib list, but I will start
here.  Please feel free to redirect this post...]

While tracking down a Cygwin Python problem, I believe that I have
uncovered an overflow problem in realloc() (and possibly other malloc
routines).  The attached test program, realloc.cc, demonstrates the
problem:

    $ realloc 536870911  # realloc((maximum int value) / 4) fails
    realloc(536870911) failed
    $ realloc 2147483647 # realloc(maximum int value) "succeeds"
    $

The attached patch "fixes" the overflow problem by changing many (long)
casts into (unsigned long) ones:

    $ realloc 2147483647
    realloc(2147483647) failed

Is this the right approach?  Or, is there a better way?

Thanks,
Jason

Attachment: realloc.cc
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Attachment: mallocr.c.diff
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