web2c 7.3.2 (TeX and Metafont) bounds violations

Nelson H. F. Beebe beebe@math.utah.edu
Mon, 11 Sep 2000 12:37:24 -0600 (MDT)


There has been recent work on extended the gcc compiler to support
bounded pointers: each OBJECT* pointer points to a 3-element structure
containing the object's current address, and lower and upper bounds on
the storage allocated for the object.  You can read about it in

	http://gcc.gnu.org/projects/bp

The reason for this post is to inform you that as part of the project,
a number of open-source programs were built and tested with the
extended gcc compiler, among them web2c 7.3.2, for which the above Web
page notes

>> ...
>> Bounds violations exposed:
>> 
>>     * fixwrites: main read past the beginning of a string buffer when
>> 	  presented with an empty line. 
>> 
>>     100% of the test suite passes after fixing the bug listed above,
>>     and compiling with ``gcc ... -fno-strict-aliasing''. A
>>     strict-aliasing bug for i586 and i686 caused two assertion
>>     failures in kpathsea. 
>> ...

Since TeXlive CDs are in production these past few months, it would be
beneficial to incorporate fixes in new editions.  I suspect that one
or more commercial implementations of TeX also involve Web-to-C
translations, so the fixes may be more widely applicable.

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