Once you've found a bug, make sure it's really a bug. A good way to do this is to see if the GNU C library behaves the same way some other C library does. If so, probably you are wrong and the libraries are right (but not necessarily). If not, one of the libraries is probably wrong.
Next, go to http://www-gnats.gnu.ai.mit.edu:8080/cgi-bin/wwwgnats.pl, and look through the bug database. Check here to verify the problem has not already be reported.
Once you're sure you've found a new bug, try to narrow it down to the smallest test case that reproduces the problem. In the case of a C library, you really only need to narrow it down to one library function call, if possible. This should not be too difficult.
The final step when you have a simple test case is to report the bug. When reporting a bug, send your test case, the results you got, the results you expected, what you think the problem might be (if you've thought of anything), your system type, and the version of the GNU C library which you are using. Also include the files `config.status' and `config.make' which are created by running `configure`; they will be in whatever directory was current when you ran `configure'.
All bug reports for the GNU C library should be sent using the
glibcbug
shell script which comes with the GNU libc to
bugs@gnu.ai.mit.edu, or submitted through the GNATS web
interface at
http://www-gnats.gnu.ai.mit.edu:8080/cgi-bin/wwwgnats.pl.
Suggestions and questions should be sent to the mailing list at bugs-glibc@prep.ai.mit.edu. If you don't read the gnewsgroup gnu.bug.glibc, you can subscribe to the list by asking bug-glibc-request@prep.ai.mit.edu.
Please DO NOT send bug report for the GNU C library to <bug-gcc@prep.ai.mit.edu>. That list is for bug reports for GNU CC. GNU CC and the GNU C library are separate entities maintained by separate people.