comments from review

gossip/src/crds_value.rs

@@ -15,7 +15,11 @@ use {
     solana_sanitize::{Sanitize, SanitizeError},
     solana_signature::Signature,
     solana_signer::Signer,
-    std::borrow::{Borrow, Cow},
+    std::{
+        borrow::{Borrow, Cow},
+        io::Cursor,
+        mem::MaybeUninit,
+    },
 };
 
 /// CrdsValue that is replicated across the cluster
@@ -228,13 +232,17 @@ impl<'de> Deserialize<'de> for CrdsValue {
             data: CrdsData,
         }
         let CrdsValue { signature, data } = CrdsValue::deserialize(deserializer)?;
-        let mut buffer = [0u8; PACKET_DATA_SIZE];
+        // To compute the hash of the received CrdsData we need to re-serialize it
+        // PACKET_DATA_SIZE is always enough since we have just received the value in a packet
+        let mut buffer: MaybeUninit<[u8; PACKET_DATA_SIZE]> = MaybeUninit::uninit();
+        // SAFETY: we are only using this buffer to store serialize results
+        let buf_ref = unsafe { buffer.assume_init_mut() };
         let position = {
-            let mut cursor = std::io::Cursor::new(buffer.as_mut());
+            let mut cursor = Cursor::new(buf_ref.as_mut());
             bincode::serialize_into(&mut cursor, &data).map_err(serde::de::Error::custom)?;
             cursor.position() as usize
         };
-        let hash = solana_sha256_hasher::hashv(&[signature.as_ref(), &buffer[0..position]]);
+        let hash = solana_sha256_hasher::hashv(&[signature.as_ref(), &buf_ref[0..position]]);
         Ok(Self {
             signature,
             data,