libidn-1.25: Fedora release 15 (Lovelock) x86_64 failure, and workaround

[Nelson H. F. Beebe]

When I built libidn-1.25 on Fedora release 15 (Lovelock) x86_64 with

        %  set  path=( /bin /usr/bin )
        %  gcc --version
        gcc (GCC) 4.6.3 20120306 (Red Hat 4.6.3-2)
        % ./configure --libdir=/usr/local/lib64 4 && make all check

I got these test failures:

        ==6976== Invalid read of size 4
        ==6976==    at 0x4C116C5: idna_to_ascii_4z (idna.c:526)
        ==6976==    by 0x4C11944: idna_to_ascii_8z (idna.c:579)
        ==6976==    by 0x400B15: doit (tst_idna2.c:485)
        ==6976==    by 0x40090C: main (utils.c:146)
        ==6976==  Address 0x515b8d8 is 8 bytes inside a block of size 10 alloc'd
        ==6976==    at 0x4A0649D: malloc (vg_replace_malloc.c:236)
        ==6976==    by 0x4C11810: idna_to_ascii_4z (idna.c:540)
        ==6976==    by 0x4C11944: idna_to_ascii_8z (idna.c:579)
        ==6976==    by 0x400B15: doit (tst_idna2.c:485)
        ==6976==    by 0x40090C: main (utils.c:146)
        ==6976==
        ==6976== Invalid read of size 4
        ==6976==    at 0x4C116B0: idna_to_ascii_4z (idna.c:526)
        ==6976==    by 0x4C11944: idna_to_ascii_8z (idna.c:579)
        ==6976==    by 0x400B15: doit (tst_idna2.c:485)
        ==6976==    by 0x40090C: main (utils.c:146)
        ==6976==  Address 0x5169ae0 is 0 bytes inside a block of size 3 alloc'd
        ==6976==    at 0x4A0649D: malloc (vg_replace_malloc.c:236)
        ==6976==    by 0x4C11810: idna_to_ascii_4z (idna.c:540)
        ==6976==    by 0x4C11944: idna_to_ascii_8z (idna.c:579)
        ==6976==    by 0x400B15: doit (tst_idna2.c:485)
        ==6976==    by 0x40090C: main (utils.c:146)
        ==6976==
        FAIL: tst_idna2

        ==6984== Invalid read of size 4
        ==6984==    at 0x4C116B0: idna_to_ascii_4z (idna.c:526)
        ==6984==    by 0x4C11944: idna_to_ascii_8z (idna.c:579)
        ==6984==    by 0x400981: doit (tst_idna4.c:45)
        ==6984==    by 0x4007CC: main (utils.c:146)
        ==6984==  Address 0x515b2d4 is 4 bytes inside a block of size 7 alloc'd
        ==6984==    at 0x4A0649D: malloc (vg_replace_malloc.c:236)
        ==6984==    by 0x4C11810: idna_to_ascii_4z (idna.c:540)
        ==6984==    by 0x4C11944: idna_to_ascii_8z (idna.c:579)
        ==6984==    by 0x400981: doit (tst_idna4.c:45)
        ==6984==    by 0x4007CC: main (utils.c:146)
        ==6984==
        FAIL: tst_idna4

        ===================================
        2 of 12 tests failed
        Please report to address@hidden
        ===================================

Fortunately, I've built dozens of versions of gcc on our systems, so I
tried a fresh build with gcc (GCC) 4.4.6 20110301, and all tests then
passed.

If others are seeing similar failures with gcc-4.6.3, then we may have
a compiler code-generation error.  However, the out-of-bounds reports
suggest that it could also be an error in libidn from creating
objects, then referencing pointers just outside them.


-------------------------------------------------------------------------------
- Nelson H. F. Beebe                    Tel: +1 801 581 5254                  -
- University of Utah                    FAX: +1 801 581 4148                  -
- Department of Mathematics, 110 LCB    Internet e-mail: address@hidden  -
- 155 S 1400 E RM 233                       address@hidden  address@hidden -
- Salt Lake City, UT 84112-0090, USA    URL: http://www.math.utah.edu/~beebe/ -
-------------------------------------------------------------------------------