OSV-2023-443 Use-after-poison in file_is_simh

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=59438 Crash type: Use-after-poison READ 4 Crash state: fileissimh filebuffer magicbuffer...

OSV-2022-924 Heap-buffer-overflow in file_zmagic

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=51608 Crash type: Heap-buffer-overflow READ 1 Crash state: filezmagic filebuffer magicbuffer...