ensure no NULL is passed to memcpy

NULL is valid when size is 0, but memcpy uses nonnull attributes,
so let's not poke the bear

2 files changed, 14 insertions, 6 deletions

diff --git a/contrib/epee/src/buffer.cpp b/contrib/epee/src/buffer.cpp
index d637b905e..10ea6de56 100644
--- a/contrib/epee/src/buffer.cpp
+++ b/contrib/epee/src/buffer.cpp
@@ -64,7 +64,8 @@ void buffer::append(const void *data, size_t sz)
       size_t reserve = (((size() + sz) * 3 / 2) + 4095) & ~4095;
       new_storage.reserve(reserve);
       new_storage.resize(size());
-      memcpy(new_storage.data(), storage.data() + offset, storage.size() - offset);
+      if (size() > 0)
+        memcpy(new_storage.data(), storage.data() + offset, storage.size() - offset);
       offset = 0;
       std::swap(storage, new_storage);
     }
diff --git a/contrib/epee/src/wipeable_string.cpp b/contrib/epee/src/wipeable_string.cpp
index 3a6ee5dac..4209b71bf 100644
--- a/contrib/epee/src/wipeable_string.cpp
+++ b/contrib/epee/src/wipeable_string.cpp
@@ -62,13 +62,15 @@ wipeable_string::wipeable_string(wipeable_string &&other)
 wipeable_string::wipeable_string(const std::string &other)
 {
   grow(other.size());
-  memcpy(buffer.data(), other.c_str(), size());
+  if (size() > 0)
+    memcpy(buffer.data(), other.c_str(), size());
 }
 
 wipeable_string::wipeable_string(std::string &&other)
 {
   grow(other.size());
-  memcpy(buffer.data(), other.c_str(), size());
+  if (size() > 0)
+    memcpy(buffer.data(), other.c_str(), size());
   if (!other.empty())
   {
     memwipe(&other[0], other.size()); // we're kinda left with this again aren't we
@@ -79,7 +81,8 @@ wipeable_string::wipeable_string(std::string &&other)
 wipeable_string::wipeable_string(const char *s)
 {
   grow(strlen(s));
-  memcpy(buffer.data(), s, size());
+  if (size() > 0)
+    memcpy(buffer.data(), s, size());
 }
 
 wipeable_string::wipeable_string(const char *s, size_t len)
@@ -112,14 +115,18 @@ void wipeable_string::grow(size_t sz, size_t reserved)
   }
   size_t old_sz = buffer.size();
   std::unique_ptr<char[]> tmp{new char[old_sz]};
-  memcpy(tmp.get(), buffer.data(), old_sz * sizeof(char));
   if (old_sz > 0)
+  {
+    memcpy(tmp.get(), buffer.data(), old_sz * sizeof(char));
     memwipe(buffer.data(), old_sz * sizeof(char));
+  }
   buffer.reserve(reserved);
   buffer.resize(sz);
-  memcpy(buffer.data(), tmp.get(), old_sz * sizeof(char));
   if (old_sz > 0)
+  {
+    memcpy(buffer.data(), tmp.get(), old_sz * sizeof(char));
     memwipe(tmp.get(), old_sz * sizeof(char));
+  }
 }
 
 void wipeable_string::push_back(char c)