Prevent 32-bit size_t integer overflow in absl::Cord append and iteration PiperOrigin-RevId: 945407881 Change-Id: I7ac24c3fc113ed1d275483702f622c0f2ae11495

diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index 584a3c6..5827d89 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc

@@ -455,6 +455,9 @@
 
   contents_.MaybeRemoveEmptyCrcNode();
   if (src.empty()) return;
+  ABSL_RAW_CHECK(src.contents_.size() <=
+                     std::numeric_limits<size_t>::max() - contents_.size(),
+                 "Cord length overflow");
 
   if (empty()) {
     // Since destination is empty, we can avoid allocating a node,
@@ -566,6 +569,9 @@
 void Cord::Prepend(const Cord& src) {
   contents_.MaybeRemoveEmptyCrcNode();
   if (src.empty()) return;
+  ABSL_RAW_CHECK(src.contents_.size() <=
+                     std::numeric_limits<size_t>::max() - contents_.size(),
+                 "Cord length overflow");
 
   CordRep* src_tree = src.contents_.tree();
   if (src_tree != nullptr) {

diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index c5b2ec4..7e80259 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h

@@ -1621,11 +1621,13 @@
 
 inline Cord::ChunkIterator::reference Cord::ChunkIterator::operator*() const {
   absl::base_internal::HardeningAssertGT(bytes_remaining_, size_t{0});
+  ABSL_ASSERT(bytes_remaining_ >= current_chunk_.size());
   return current_chunk_;
 }
 
 inline Cord::ChunkIterator::pointer Cord::ChunkIterator::operator->() const {
   absl::base_internal::HardeningAssertGT(bytes_remaining_, size_t{0});
+  ABSL_ASSERT(bytes_remaining_ >= current_chunk_.size());
   return &current_chunk_;
 }