Add a LOG(DFATAL) if the sequence number length is too small to fit the

net/quic/quic_framer.cc

Index: net/quic/quic_framer.cc
diff --git a/net/quic/quic_framer.cc b/net/quic/quic_framer.cc
index 588db7483ed4c689284962f34eaf8e200c1f9fe0..90d9a89b829ab59946dd2797bb42ad2748e40af3 100644
--- a/net/quic/quic_framer.cc
+++ b/net/quic/quic_framer.cc
@@ -2049,6 +2049,15 @@ bool QuicFramer::AppendAckFrameAndTypeByte(
   DCHECK_GE(header.packet_sequence_number, frame.sent_info.least_unacked);
   const QuicPacketSequenceNumber least_unacked_delta =
       header.packet_sequence_number - frame.sent_info.least_unacked;
+  const QuicPacketSequenceNumber length_shift =
+      header.public_header.sequence_number_length * 8;
+  if (least_unacked_delta >> length_shift > 0) {
+    LOG(DFATAL) << "sequence_number_length "
+                << header.public_header.sequence_number_length
+                << " is too small for least_unacked_delta: "
+                << least_unacked_delta;
+    return false;
+  }
   if (!AppendPacketSequenceNumber(header.public_header.sequence_number_length,
                                   least_unacked_delta, writer)) {
     return false;