check multiplication overflow

Author: ian-shim

encoding/params.go

@@ -11,6 +11,8 @@ var (
 	ErrInvalidParams = errors.New("invalid encoding params")
 )
 
+const maxUint64 = ^uint64(0)
+
 type EncodingParams struct {
 	ChunkLength uint64 // ChunkSize is the length of the chunk in symbols
 	NumChunks   uint64
@@ -61,6 +63,9 @@ func GetNumSys(dataSize uint64, chunkLen uint64) uint64 {
 
 // ValidateEncodingParams takes in the encoding parameters and returns an error if they are invalid.
 func ValidateEncodingParams(params EncodingParams, SRSOrder uint64) error {
+	if params.ChunkLength != 0 && params.NumChunks > maxUint64/params.ChunkLength {
+		return fmt.Errorf("multiplication overflow: ChunkLength: %d, NumChunks: %d", params.ChunkLength, params.NumChunks)
+	}
 
 	// Check that the parameters are valid with respect to the SRS. The precomputed terms of the amortized KZG
 	// prover use up to order params.ChunkLen*params.NumChunks-1 for the SRS, so we must have