read/macho: handle invalid cmdsize and section align

crates/examples/src/objdump.rs

@@ -219,20 +219,28 @@ fn dump_parsed_object<W: Write, E: Write>(w: &mut W, e: &mut E, file: &object::F
         }
     }
 
-    let imports = file.imports().unwrap();
-    if !imports.is_empty() {
-        writeln!(w)?;
-        for import in imports {
-            writeln!(w, "{:?}", import)?;
+    match file.imports() {
+        Ok(imports) => {
+            if !imports.is_empty() {
+                writeln!(w)?;
+                for import in imports {
+                    writeln!(w, "{:x?}", import)?;
+                }
+            }
         }
+        Err(err) => writeln!(e, "Failed to parse imports: {}", err)?,
     }
 
-    let exports = file.exports().unwrap();
-    if !exports.is_empty() {
-        writeln!(w)?;
-        for export in exports {
-            writeln!(w, "{:x?}", export)?;
+    match file.exports() {
+        Ok(exports) => {
+            if !exports.is_empty() {
+                writeln!(w)?;
+                for export in exports {
+                    writeln!(w, "{:x?}", export)?;
+                }
+            }
         }
+        Err(err) => writeln!(e, "Failed to parse exports: {}", err)?,
     }
 
     Ok(())

src/read/macho/load_command.rs

@@ -1,10 +1,11 @@
 use core::marker::PhantomData;
+use core::mem;
 
 use crate::endian::Endian;
 use crate::macho;
 use crate::pod::Pod;
 use crate::read::macho::{MachHeader, SymbolTable};
-use crate::read::{Bytes, ReadError, ReadRef, Result, StringTable};
+use crate::read::{Bytes, Error, ReadError, ReadRef, Result, StringTable};
 
 /// An iterator over the load commands of a `MachHeader`.
 #[derive(Debug, Default, Clone, Copy)]
@@ -34,6 +35,9 @@ impl<'data, E: Endian> LoadCommandIterator<'data, E> {
             .read_error("Invalid Mach-O load command header")?;
         let cmd = header.cmd.get(self.endian);
         let cmdsize = header.cmdsize.get(self.endian) as usize;
+        if cmdsize < mem::size_of::<macho::LoadCommand<E>>() {
+            return Err(Error("Invalid Mach-O load command size"));
+        }
         let data = self
             .data
             .read_bytes(cmdsize)
@@ -351,3 +355,19 @@ impl<E: Endian> macho::SymtabCommand<E> {
         Ok(SymbolTable::new(symbols, strings))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::LittleEndian;
+
+    #[test]
+    fn cmd_size_invalid() {
+        let mut commands = LoadCommandIterator::new(LittleEndian, &[0; 8], 10);
+        assert!(commands.next().is_err());
+        let mut commands = LoadCommandIterator::new(LittleEndian, &[0, 0, 0, 0, 7, 0, 0, 0, 0], 10);
+        assert!(commands.next().is_err());
+        let mut commands = LoadCommandIterator::new(LittleEndian, &[0, 0, 0, 0, 8, 0, 0, 0, 0], 10);
+        assert!(commands.next().is_ok());
+    }
+}

src/read/macho/section.rs

@@ -120,7 +120,12 @@ where
 
     #[inline]
     fn align(&self) -> u64 {
-        1 << self.internal.section.align(self.file.endian)
+        let align = self.internal.section.align(self.file.endian);
+        if align < 64 {
+            1 << align
+        } else {
+            0
+        }
     }
 
     #[inline]