Libarchive: double-free vulnerability in rar5 decompression logic via dangling filtered_buf pointer in init_unpack()

A double free issue has been identified in libarchive's RAR5 reader. During parsing of a specially crafted RAR5 archive, the filtered_buf pointer may remain stale after being freed during unpacking state reinitialization. Subsequent processing of another archive entry can trigger a second free of the same memory region, resulting in a double-free condition. Successful exploitation may cause applications using the vulnerable libarchive API to terminate unexpectedly, leading to a denial of service.