If you use SELinux, you need to ensure that the httpd_enable_cgi boolean is
set properly.  This can be done via the command line, e.g.:

   # setsebool -P httpd_enable_cgi 1

Or you can use the graphical tool system-config-selinux, via System ->
Administration -> SELinux Management on the Gnome menu.

Additionally, the git repositories need to be readable by the cgi.  This is
handled automatically for repositories in the default path, /var/lib/git.  If
your repositories are in a different path, /srv/git, for example, you can set
the proper context using semanage:

    # semanage fcontext -a -t git_sys_content_t "/srv/git(/.*)?"

If you have other confined daemons that need to access the git repositories,
you may want to use public_content_t, or public_content_rw_t instead.

Then use restorecon to update the contexts:

    # restorecon -RF /srv/git