tar-rs: unpack_in can chmod arbitrary directories by following symlinks

tar-rs is a tar archive reading/writing library for Rust. In versions 0.4.44 and below, when unpacking a tar archive, the tar crate's unpack_dir function uses fs::metadata() to check whether a path that already exists is a directory. Because fs::metadata() follows symbolic links, a crafted tarball containing a symlink entry followed by a directory entry with the same name causes the crate to treat the symlink target as a valid existing directory — and subsequently apply chmod to it. This allows an attacker to modify the permissions of arbitrary directories outside the extraction root. This issue has been fixed in version 0.4.45.