byte_view: avoid UB when determining buffer address from iterator

riebl · Dec 4, 2024 · 8c70334 · 8c70334
1 parent 08ec1b7
commit 8c70334
Show file tree

Hide file tree

Showing 2 changed files with 24 additions and 7 deletions.
diff --git a/vanetza/common/byte_view.cpp b/vanetza/common/byte_view.cpp
@@ -6,10 +6,26 @@
 namespace vanetza
 {
 
-byte_view_range::byte_view_range(
-        const ByteBuffer::const_iterator& begin,
-        const ByteBuffer::const_iterator& end) :
-    iterator_range(begin, end)
+namespace
+{
+
+boost::iterator_range<byte_view_iterator>
+make_safe_range(const ByteBuffer::const_iterator& begin, const ByteBuffer::const_iterator& end)
+{
+    if (begin < end) {
+        byte_view_iterator vbegin { begin };
+        byte_view_iterator vend { std::next(vbegin, std::distance(begin, end)) };
+        return boost::iterator_range<byte_view_iterator> { vbegin, vend };
+    } else {
+        byte_view_iterator empty;
+        return boost::iterator_range<byte_view_iterator> { empty, empty };
+    }
+}
+
+}
+
+byte_view_range::byte_view_range(const ByteBuffer::const_iterator& begin, const ByteBuffer::const_iterator& end) :
+    iterator_range(make_safe_range(begin, end))
 {
 }
 
@@ -19,7 +35,7 @@ byte_view_range::byte_view_range(const byte_view_iterator& begin, const byte_vie
 }
 
 byte_view_range::byte_view_range(ByteBuffer&& _buffer) :
-    iterator_range(_buffer.begin(), _buffer.end()), buffer(std::move(_buffer))
+    iterator_range(make_safe_range(_buffer.begin(), _buffer.end())), buffer(std::move(_buffer))
 {
 }
 

diff --git a/vanetza/common/byte_view.hpp b/vanetza/common/byte_view.hpp
@@ -2,6 +2,7 @@
 #define BYTE_VIEW_HPP_TXN2ISMB
 
 #include <vanetza/common/byte_buffer.hpp>
+#include <boost/core/pointer_traits.hpp>
 #include <boost/range/iterator_range.hpp>
 #include <iterator>
 #include <memory>
@@ -23,7 +24,7 @@ class byte_view_iterator
 
     byte_view_iterator() = default;
     explicit byte_view_iterator(pointer p) : m_iterator(p) {}
-    explicit byte_view_iterator(const ByteBuffer::const_iterator& it) : m_iterator(&*it) {}
+    explicit byte_view_iterator(const ByteBuffer::const_iterator& it) : m_iterator(boost::to_address(it)) {}
 
     constexpr value_type operator*() const
     {
@@ -153,7 +154,7 @@ class byte_view_range : private boost::iterator_range<byte_view_iterator>
      * \param buffer pass buffer via rvalue
      * \note View is valid without limitation
      */
-    byte_view_range(ByteBuffer&&);
+    explicit byte_view_range(ByteBuffer&&);
 
     /**
      * Get pointer to start of contiguous buffer memory