The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard math libraries (libm), and the Name Server Caching Daemon (nscd) used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly.
An out-of-bounds read flaw was found in the way glibc's iconv() function converted certain encoded data to UTF-8. An attacker able to make an application call the iconv() function with a specially crafted argument could use this flaw to crash that application. (CVE-2014-6040)
It was found that the files back end of Name Service Switch (NSS) did not isolate iteration over an entire database from key-based look-up API calls. An application performing look-ups on a database while iterating over it could enter an infinite loop, leading to a denial of service. (CVE-2014-8121)
This update also fixes the following bugs:
Due to problems with buffer extension and reallocation, the nscd daemon terminated unexpectedly with a segmentation fault when processing long netgroup entries. With this update, the handling of long netgroup entries has been corrected and nscd no longer crashes in the described scenario. (BZ#1138520)
If a file opened in append mode was truncated with the ftruncate() function, a subsequent ftell() call could incorrectly modify the file offset. This update ensures that ftell() modifies the stream state only when it is in append mode and the buffer for the stream is not empty. (BZ#1156331)
A defect in the C library headers caused builds with older compilers to generate incorrect code for the btowc() function in the older compatibility C++ standard library. Applications calling btowc() in the compatibility C++ standard library became unresponsive. With this update, the C library headers have been corrected, and the compatibility C++ standard library shipped with Red Hat Enterprise Linux has been rebuilt. Applications that rely on the compatibility C++ standard library no longer hang when calling btowc(). (BZ#1120490)
Previously, when using netgroups and the nscd daemon was set up to cache netgroup information, the sudo utility denied access to valid users. The bug in nscd has been fixed, and sudo now works in netgroups as expected. (BZ#1080766)
Users of glibc are advised to upgrade to these updated packages, which fix these issues.