CVE-2013-0222: Buffer Overflow in coreutils sort via getmonth() with locale month names

The sort command in GNU coreutils (version 8.20) contains a stack buffer overflow vulnerability in the getmonth() function when processing month-based sorting (-M flag) with locale-specific month abbreviations. The vulnerability occurs because getmonth() increments an input pointer (m) past the end of the input buffer when comparing against month names. This out-of-bounds pointer is then used to calculate field limits in keycompare(), leading to a huge lena value that overflows the 4000-byte stack buffer when copying key data.