ID3v2: Fix panic on empty UTF-16 strings with no BOM

Author: Serial-ATA

lofty/src/id3/v2/items/language_frame.rs

@@ -2,6 +2,7 @@ use crate::error::{Id3v2Error, Id3v2ErrorKind, Result};
 use crate::id3::v2::frame::content::verify_encoding;
 use crate::id3::v2::header::Id3v2Version;
 use crate::id3::v2::{FrameFlags, FrameHeader, FrameId};
+use crate::macros::err;
 use crate::tag::items::Lang;
 use crate::util::text::{
 	DecodeTextResult, TextDecodeOptions, TextEncoding, decode_text, encode_text,
@@ -55,8 +56,7 @@ impl LanguageFrame {
 			endianness = match bom {
 				[0xFF, 0xFE] => u16::from_le_bytes,
 				[0xFE, 0xFF] => u16::from_be_bytes,
-				// The BOM has to be valid for `decode_text` to succeed
-				_ => unreachable!("Bad BOM {bom:?}"),
+				_ => err!(TextDecode("UTF-16 string missing a BOM")),
 			};
 		}
 

lofty/src/id3/v2/items/sync_text.rs

@@ -166,8 +166,7 @@ impl SynchronizedTextFrame<'_> {
 			endianness = match bom {
 				[0xFF, 0xFE] => u16::from_le_bytes,
 				[0xFE, 0xFF] => u16::from_be_bytes,
-				// Since the description was already read, we can assume the BOM was valid
-				_ => unreachable!("Bad BOM {bom:?}"),
+				_ => err!(TextDecode("UTF-16 string missing a BOM")),
 			};
 		}
 

lofty/tests/fuzz/assets/mpegfile_read_from/00. Dzienniki Gwiazdowe_IDX_4_RAND_1362730390282399020432565_minimized_242.mp3

@@ -40,6 +40,15 @@ fn crash5() {
 	let _ = MpegFile::read_from(&mut reader, ParseOptions::new());
 }
 
+#[test_log::test]
+fn crash6() {
+	let mut reader = get_reader(
+		"mpegfile_read_from/00. Dzienniki \
+		 Gwiazdowe_IDX_4_RAND_1362730390282399020432565_minimized_242.mp3",
+	);
+	let _ = MpegFile::read_from(&mut reader, ParseOptions::new());
+}
+
 #[test_log::test]
 fn oom1() {
 	oom_test::<MpegFile>("mpegfile_read_from/oom-f8730cbfa5682ab12343ccb70de9b71a061ef4d0");