file: Buffer over-write in finfo_open with malformed magic file

The filecheckmem function in funcs.c in file before 5.23, as used in the Fileinfo component in PHP before 5.5.34, 5.6.x before 5.6.20, and 7.x before 7.0.5, mishandles continuation-level jumps, which allows context-dependent attackers to cause a denial of service buffer overflow and application...