CVE-2023-4911 Looney Tunables Stack Buffer Overflow in glibc __tunables_init

glibc 2.37's dynamic linker has a buffer overflow vulnerability in GLIBC_TUNABLES environment variable processing. When __tunables_init calls parse_tunables in setuid/setgid context, a small buffer (16 bytes for the name) is allocated but then used to store the reconstructed full tunable string (name=value pairs). The parse_tunables function writes canonical tunable names and values back to this buffer without bounds checking, causing stack overflow.