fix(x/interchainstaking/types): fuzz & fix DetermineAllocationsForUnd…

…elegation

This change introduces a fuzzer for DetermineAllocationsForUndelegation
as well as fixes for the identified non-defensive bugs that were
reported from ~1.5hr of fuzzing.

Fixes quicksilver-zone#1544
Fixes quicksilver-zone#1545
Fixes quicksilver-zone#1546

x/interchainstaking/types/delegation.go

@@ -125,12 +125,21 @@ func (vi ValidatorIntents) MustGetForValoper(valoper string) *ValidatorIntent {
 func (vi ValidatorIntents) Normalize() ValidatorIntents {
 	total := sdk.ZeroDec()
 	for _, i := range vi {
-		total = total.AddMut(i.Weight)
+		if !i.Weight.IsNil() {
+			total = total.AddMut(i.Weight)
+		}
 	}
 
 	out := make(ValidatorIntents, 0)
+
+	if total.IsZero() {
+		return out
+	}
+
 	for _, i := range vi {
-		out = append(out, &ValidatorIntent{ValoperAddress: i.ValoperAddress, Weight: i.Weight.Quo(total)})
+		if !i.Weight.IsNil() {
+			out = append(out, &ValidatorIntent{ValoperAddress: i.ValoperAddress, Weight: i.Weight.Quo(total)})
+		}
 	}
 	return out.Sort()
 }

x/interchainstaking/types/rebalance.go

@@ -50,6 +50,9 @@ func CalculateAllocationDeltas(
 		if !ok {
 			target = &ValidatorIntent{ValoperAddress: valoper, Weight: sdk.ZeroDec()}
 		}
+		if target.Weight.IsNil() {
+			continue
+		}
 		targetAmount := target.Weight.MulInt(currentSum).TruncateInt()
 
 		// diff between target and current allocations

x/interchainstaking/types/redemptions.go

@@ -27,7 +27,11 @@ func DetermineAllocationsForUndelegation(currentAllocations map[string]math.Int,
 		return outWeights, fmt.Errorf("amount was invalid, expected sdk.Coins of length 1, got length %d", len(amount))
 	}
 
-	if !amount[0].Amount.IsPositive() {
+	if availablePerValidator == nil {
+		availablePerValidator = make(map[string]math.Int)
+	}
+
+	if amount[0].Amount.IsNil() || !amount[0].Amount.IsPositive() {
 		return outWeights, fmt.Errorf("amount was invalid, expected positive value, got %s", amount[0].Amount.String())
 	}
 	input := amount[0].Amount
@@ -52,7 +56,10 @@ func DetermineAllocationsForUndelegation(currentAllocations map[string]math.Int,
 		for idx := range overAllocated {
 			// use Amount+1 in the line below to avoid 1 remaining where truncation leaves 1 remaining - e.g. 1000 => 333/333/333 + 1.
 			outWeights[overAllocated[idx].ValoperAddress] = sdk.NewDecFromInt(overAllocated[idx].Amount).Quo(sdk.NewDecFromInt(sum)).Mul(sdk.NewDecFromInt(overAllocationSplit)).TruncateInt()
-			if outWeights[overAllocated[idx].ValoperAddress].GT(availablePerValidator[overAllocated[idx].ValoperAddress]) {
+			overAlloc := availablePerValidator[overAllocated[idx].ValoperAddress]
+			if overAlloc.IsNil() {
+				availablePerValidator[overAllocated[idx].ValoperAddress] = sdk.ZeroInt()
+			} else if outWeights[overAllocated[idx].ValoperAddress].GT(overAlloc) {
 				// use up all of overAllocated[idx] and set available to zero.
 				outWeights[overAllocated[idx].ValoperAddress] = availablePerValidator[overAllocated[idx].ValoperAddress]
 				availablePerValidator[overAllocated[idx].ValoperAddress] = sdk.ZeroInt()
@@ -132,7 +139,12 @@ func DetermineAllocationsForUndelegation(currentAllocations map[string]math.Int,
 		// remove validators with no remaining balance from intents, and split remaining amount proportionally.
 		newTargetAllocations := make(ValidatorIntents, 0, len(targetAllocations))
 		for idx := range targetAllocations.Sort() {
-			if !availablePerValidator[targetAllocations[idx].ValoperAddress].IsZero() {
+			targetAlloc := availablePerValidator[targetAllocations[idx].ValoperAddress]
+			if targetAlloc.IsNil() {
+				continue
+			}
+
+			if !targetAlloc.IsZero() {
 				newTargetAllocations = append(newTargetAllocations, targetAllocations[idx])
 			}
 		}
@@ -170,8 +182,17 @@ func DetermineAllocationsForUndelegation(currentAllocations map[string]math.Int,
 	// the delta calculations on the next run.
 	dust := amount[0].Amount.Sub(outSum)
 	for idx := 0; idx <= len(deltas)-1; idx++ {
-		if dust.LTE(availablePerValidator[deltas[idx].ValoperAddress]) {
-			outWeights[deltas[idx].ValoperAddress] = outWeights[deltas[idx].ValoperAddress].Add(dust)
+		gotForValoper := availablePerValidator[deltas[idx].ValoperAddress]
+		if gotForValoper.IsNil() {
+			continue
+		}
+		if dust.LTE(gotForValoper) {
+			outWeight := outWeights[deltas[idx].ValoperAddress]
+			if outWeight.IsNil() {
+				outWeight = sdk.ZeroInt()
+			}
+
+			outWeights[deltas[idx].ValoperAddress] = outWeight.Add(dust)
 			break
 		}
 	}
@@ -189,6 +210,9 @@ func DetermineAllocationsForUndelegationPredef(currentAllocations map[string]mat
 		return outWeights, fmt.Errorf("amount was invalid, expected positive value, got %d", amount[0].Amount.Int64())
 	}
 	input := amount[0].Amount
+	if currentSum.IsNil() {
+		currentSum = sdk.ZeroInt()
+	}
 	underAllocated, overAllocated := CalculateAllocationDeltas(currentAllocations, lockedAllocations, currentSum /* .Sub(input) */, targetAllocations, make(map[string]math.Int))
 
 	outSum := sdk.ZeroInt()