Re: Check failed for libidn-1.24 with glibc 2.14.1

[Simon Josefsson]

Funda Wang <address@hidden> writes:

> Hello,
>
> I'm currently build libidn-1.24 with glibc 2.14.1/valgrind 3.7 under
> Mageia cauldron. All builds fine, except that `make check' failed
> after building. Log here:
>
> PASS: tst_idna
> ==25261== Invalid read of size 4
> ==25261==    at 0x4E328E5: idna_to_ascii_4z (idna.c:526)
>
> i.e., idna2 and idna4 tests are failed. Is it a bug in libidn or
> valgrind? Regards.

It is a valgrind issue, the line reads:

          size_t l = strlen (out) + 1 + strlen (buf) + 1;

It is the glibc implementation of strlen that is optimized to read past
the buffer, and valgrind detects this.

The normal way to deal with this is to write a valgrind suppressions
file.

I'm leaning more and more to disable valgrind by default, it generates
false positives like this...  perhaps it is sufficient that I run it,
and people can enable it with --enable-valgrind-tests if they want it.

/Simon