The glibc packages provide the standard C and standard math libraries used by multiple programs on the system. Without these libraries, the Linux system cannot function properly. It was discovered that the formatted printing functionality in glibc did not properly restrict the use of alloca. This could allow an attacker to bypass FORTIFY_SOURCE protections and execute arbitrary code using a format string flaw in an application, even though these protections are expected to limit the impact of such flaws to an application abort. This update also fixes the following bug: * If a file or a string was in the IBM-930 encoding, and contained the invalid multibyte character "0xffff", attempting to use iconv to convert that file or string to another encoding, such as UTF-8, resulted in a segmentation fault. With this update, the conversion code for the IBM-930 encoding recognizes this invalid character and calls an error handler, rather than causing a segmentation fault. All users of glibc are advised to upgrade to these updated packages, which contain backported patches to fix these issues.