Revert^2 "Upgrade zerocopy to 0.7.5"

893738e5702b1f065826d9a31cef2122a502da66

Change-Id: Ib91e64e7a32e6b31fa0bde93dbfc411c60d33301
diff --git a/pvmfw/src/config.rs b/pvmfw/src/config.rs
index d0a6b7f..926f42b 100644
--- a/pvmfw/src/config.rs
+++ b/pvmfw/src/config.rs
@@ -21,11 +21,11 @@
 use log::{info, warn};
 use static_assertions::const_assert_eq;
 use vmbase::util::RangeExt;
-use zerocopy::{FromBytes, LayoutVerified};
+use zerocopy::{FromBytes, FromZeroes, LayoutVerified};
 
 /// Configuration data header.
 #[repr(C, packed)]
-#[derive(Clone, Copy, Debug, FromBytes)]
+#[derive(Clone, Copy, Debug, FromZeroes, FromBytes)]
 struct Header {
     /// Magic number; must be `Header::MAGIC`.
     magic: u32,
@@ -127,7 +127,7 @@
 }
 
 #[repr(packed)]
-#[derive(Clone, Copy, Debug, FromBytes)]
+#[derive(Clone, Copy, Debug, FromZeroes, FromBytes)]
 struct HeaderEntry {
     offset: u32,
     size: u32,
@@ -147,7 +147,7 @@
 }
 
 #[repr(C, packed)]
-#[derive(Clone, Copy, Debug, Eq, FromBytes, PartialEq)]
+#[derive(Clone, Copy, Debug, Eq, FromZeroes, FromBytes, PartialEq)]
 pub struct Version {
     minor: u16,
     major: u16,