inconsistent metadata test and panic fix

src/elements/mod.rs

@@ -94,6 +94,8 @@ pub enum Error {
 	InvalidVarInt32,
 	/// Invalid VarInt64 value
 	InvalidVarInt64,
+	/// Inconsistent metadata
+	InconsistentMetadata,
 }
 
 impl fmt::Display for Error {
@@ -116,6 +118,7 @@ impl fmt::Display for Error {
 			Error::InvalidVarUint1(val) => write!(f, "Not an unsigned 1-bit integer: {}", val),
 			Error::InvalidVarInt32 => write!(f, "Not a signed 32-bit integer"),
 			Error::InvalidVarInt64 => write!(f, "Not a signed 64-bit integer"),
+			Error::InconsistentMetadata =>  write!(f, "Inconsistent metadata"),
 		}
 	}
 }
@@ -138,6 +141,7 @@ impl error::Error for Error {
 			Error::InvalidVarUint1(_) => "Not an unsigned 1-bit integer",
 			Error::InvalidVarInt32 => "Not a signed 32-bit integer",
 			Error::InvalidVarInt64 => "Not a signed 64-bit integer",
+			Error::InconsistentMetadata => "Inconsistent metadata",
 		}
 	}
 }

src/elements/module.rs

@@ -319,7 +319,7 @@ pub fn peek_size(source: &[u8]) -> usize {
 #[cfg(test)]
 mod integration_tests {
 
-	use super::super::{deserialize_file, serialize, deserialize_buffer, Section};
+	use super::super::{deserialize_file, serialize, deserialize_buffer, Section, Error};
 	use super::Module;
 
 	#[test]
@@ -468,6 +468,15 @@ mod integration_tests {
 		assert_eq!(Module::default().magic, module2.magic);
 	}
 
+	#[test]
+	fn inconsistent_meta() {
+		let result = deserialize_file("./res/cases/v1/payload_len.wasm");
+
+		// should be error, not panic
+		if let Err(Error::InconsistentMetadata) = result {}
+		else { panic!("Should return inconsistent metadata error"); }
+	}
+
 	#[test]
 	fn names() {
 		use super::super::name_section::NameSection;

src/elements/section.rs

@@ -59,9 +59,9 @@ pub enum Section {
 	Code(CodeSection),
 	/// Data definition section
 	Data(DataSection),
-	/// Name section. 
+	/// Name section.
 	///
-	/// Note that initially it is not parsed until `parse_names` is called explicitly. 
+	/// Note that initially it is not parsed until `parse_names` is called explicitly.
 	Name(NameSection),
 }
 
@@ -232,7 +232,14 @@ impl Deserialize for CustomSection {
 		let section_length: u32 = VarUint32::deserialize(reader)?.into();
 
 		let name = String::deserialize(reader)?;
-		let payload_left = section_length - (name.len() as u32 + name.len() as u32 / 128 + 1);
+		let total_naming = name.len() as u32 + name.len() as u32 / 128 + 1;
+		if total_naming > section_length {
+			return Err(Error::InconsistentMetadata)
+		} else if total_naming == section_length {
+			return Ok(CustomSection { name: name, payload: Vec::new() });
+		}
+
+		let payload_left = section_length - total_naming;
 		let mut payload = vec![0u8; payload_left as usize];
 		reader.read_exact(&mut payload[..])?;