From cc8ca5b6a5478b40546d4206392eb1471454460d Mon Sep 17 00:00:00 2001
From: Bo Yang <teboring@google.com>
Date: Mon, 19 Sep 2016 13:45:07 -0700
Subject: Integrate internal changes

---
 src/google/protobuf/arena.cc | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

(limited to 'src/google/protobuf/arena.cc')

diff --git a/src/google/protobuf/arena.cc b/src/google/protobuf/arena.cc
index 78e20946..aa4e587c 100755
--- a/src/google/protobuf/arena.cc
+++ b/src/google/protobuf/arena.cc
@@ -30,6 +30,9 @@
 
 #include <google/protobuf/arena.h>
 
+#include <algorithm>
+#include <limits>
+
 
 #ifdef ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
@@ -125,10 +128,9 @@ Arena::Block* Arena::NewBlock(void* me, Block* my_last_block, size_t n,
   } else {
     size = start_block_size;
   }
-  if (n > size - kHeaderSize) {
-    // TODO(sanjay): Check if n + kHeaderSize would overflow
-    size = kHeaderSize + n;
-  }
+  // Verify that n + kHeaderSize won't overflow.
+  GOOGLE_CHECK_LE(n, std::numeric_limits<size_t>::max() - kHeaderSize);
+  size = std::max(size, kHeaderSize + n);
 
   Block* b = reinterpret_cast<Block*>(options_.block_alloc(size));
   b->pos = kHeaderSize + n;
-- 
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