Add asserts to ensure block heights are not too large.

eth2/fork_choice/src/bitwise_lmd_ghost.rs

@@ -19,7 +19,7 @@ use types::{
 //TODO: Pruning - Children
 //TODO: Handle Syncing
 
-/// The optimised LMD-GHOST fork choice rule.
+/// The optimised bitwise LMD-GHOST fork choice rule.
 /// NOTE: This uses u32 to represent difference between block heights. Thus this is only
 /// applicable for block height differences in the range of a u32.
 /// This can potentially be parallelized in some parts.
@@ -30,6 +30,10 @@ fn log2_int(x: u32) -> u32 {
     if x == 0 {
         return 0;
     }
+    assert!(
+        x <= std::f32::MAX as u32,
+        "Height too large for fast log in bitwise fork choice"
+    );
     log2_raw(x as f32) as u32
 }
 
@@ -37,7 +41,7 @@ fn power_of_2_below(x: u32) -> u32 {
     2u32.pow(log2_int(x))
 }
 
-/// Stores the necessary data structures to run the optimised lmd ghost algorithm.
+/// Stores the necessary data structures to run the optimised bitwise lmd ghost algorithm.
 pub struct BitwiseLMDGhost<T: ClientDB + Sized> {
     /// A cache of known ancestors at given heights for a specific block.
     //TODO: Consider FnvHashMap

eth2/types/src/slot_epoch_macros.rs

@@ -25,12 +25,14 @@ macro_rules! impl_into_u32 {
     ($main: ident) => {
         impl Into<u32> for $main {
             fn into(self) -> u32 {
+                assert!(self.0 < u64::from(std::u32::MAX), "Lossy conversion to u32");
                 self.0 as u32
             }
         }
 
         impl $main {
             pub fn as_u32(&self) -> u32 {
+                assert!(self.0 < u64::from(std::u32::MAX), "Lossy conversion to u32");
                 self.0 as u32
             }
         }