improve handling of mallformed inputs

src/error.rs

@@ -9,6 +9,8 @@ pub enum ModelError {
     String(#[from] StringError),
     #[error("referenced data to {data} is out of bounds at {offset}")]
     OutOfBounds { data: &'static str, offset: usize },
+    #[error("Trying to read past the end of the file")]
+    Eof(usize),
 }
 
 #[derive(Debug, Error)]

src/lib.rs

@@ -128,7 +128,9 @@ trait Readable: Sized {
 
 impl<T: Pod> Readable for T {
     fn read(data: &[u8]) -> Result<Self, ModelError> {
-        let data = &data[0..size_of::<Self>()];
+        let data = data
+            .get(0..size_of::<Self>())
+            .ok_or(ModelError::Eof(size_of::<Self>()))?;
         Ok(pod_read_unaligned(data))
     }
 }

src/vtx/raw.rs

@@ -188,11 +188,11 @@ bitflags! {
 impl StripHeader {
     /// Index into the VVD file vertexes
     pub fn vertex_indexes(&self) -> Range<usize> {
-        self.vertex_offset as usize..(self.vertex_offset + self.vertex_count) as usize
+        self.vertex_offset as usize..(self.vertex_offset.saturating_add(self.vertex_count)) as usize
     }
 
     pub fn index_indexes(&self) -> Range<usize> {
-        self.index_offset as usize..(self.index_offset + self.index_count) as usize
+        self.index_offset as usize..(self.index_offset.saturating_add(self.index_count)) as usize
     }
 
     #[allow(dead_code)]

src/vvd/mod.rs

@@ -16,7 +16,13 @@ pub struct Vvd {
 impl Vvd {
     pub fn read(data: &[u8]) -> Result<Self> {
         let header = <VvdHeader as Readable>::read(data)?;
-        let source_vertices = read_relative(data, header.vertex_indexes(0).unwrap())?;
+        let source_vertices = read_relative(
+            data,
+            header.vertex_indexes(0).ok_or(ModelError::OutOfBounds {
+                data: "model_lod",
+                offset: 0,
+            })?,
+        )?;
         let vertices = if !header.has_fixups() {
             source_vertices
         } else {
@@ -24,10 +30,14 @@ impl Vvd {
             for fixup in read_relative_iter::<'_, VertexFileFixup, _>(data, header.fixup_indexes())
             {
                 let fixup = fixup?;
-                vertices.extend_from_slice(
-                    &source_vertices[fixup.source_vertex_id as usize
-                        ..(fixup.source_vertex_id + fixup.vertex_count) as usize],
-                );
+                let from = fixup.source_vertex_id as usize;
+                let to = (fixup.source_vertex_id.saturating_add(fixup.vertex_count)) as usize;
+                vertices.extend_from_slice(&source_vertices.get(from..to).ok_or_else(|| {
+                    ModelError::OutOfBounds {
+                        data: "source_vertices",
+                        offset: to as usize,
+                    }
+                })?);
             }
             vertices
         };