MP4: Fix division by zero panic

Author: Serial-ATA

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - **Fuzzing** (Thanks [@qarmin](https://github.com/qarmin)!) ([PR](https://github.com/Serial-ATA/lofty-rs/pull/TODO)):
+  - **MP4**: Fix panic when reading properties of a file with no timescale specified ([issue](https://github.com/Serial-ATA/lofty-rs/issues/418))
   - **WAV**: Fix panic when reading properties with large written bytes per second ([issue](https://github.com/Serial-ATA/lofty-rs/issues/420))
   - **Vorbis**: Fix panic when reading properties of a file with large absolute granule positions ([issue](https://github.com/Serial-ATA/lofty-rs/issues/421))
   - **FLAC**: Fix panic when reading properties of a file with incorrect block sizes ([issue](https://github.com/Serial-ATA/lofty-rs/issues/422))

lofty/src/mp4/properties.rs

@@ -510,7 +510,13 @@ where
 			}
 		}
 
+		// TODO: We need to eventually calculate the duration from the stts atom
+		//       if there is no timescale available.
 		let duration_millis = properties.duration.as_millis();
+		if duration_millis == 0 {
+			log::warn!("Duration is 0, unable to calculate bitrate");
+			return Ok(properties);
+		}
 
 		let overall_bitrate = u128::from(file_length * 8) / duration_millis;
 		properties.overall_bitrate = overall_bitrate as u32;

lofty/tests/fuzz/assets/mp4file_read_from/steam_at_mention_IDX_34_RAND_4491956654166691611931.m4a

@@ -1,7 +1,17 @@
 use crate::oom_test;
+use lofty::config::ParseOptions;
+use lofty::file::AudioFile;
 use lofty::mp4::Mp4File;
 
 #[test]
 fn oom1() {
 	oom_test::<Mp4File>("mp4file_read_from/oom-db2665d79ec9c045bdb9c1e9a3d0c93e7e59393e");
 }
+
+#[test]
+fn panic1() {
+	let mut reader = crate::get_reader(
+		"mp4file_read_from/steam_at_mention_IDX_34_RAND_4491956654166691611931.m4a",
+	);
+	let _ = Mp4File::read_from(&mut reader, ParseOptions::new());
+}