Merge pull request #295 from microsoft/nlexceptbug

Fix use-after-free violation in NetlinkException

src/linux/libnl-helpers/NetlinkErrorCategory.cxx

@@ -31,7 +31,7 @@ NetlinkErrorCategory::default_error_condition(int error) const noexcept
 std::error_code
 make_netlink_error_code(int error)
 {
-    return std::error_code(error, NetlinkErrorCategory());
+    return std::error_code(error, GetNetlinkErrorCategory());
 }
 
 std::error_code
@@ -44,4 +44,11 @@ MakeNetlinkErrorCode(int error)
     return make_netlink_error_code(error);
 }
 
+const NetlinkErrorCategory&
+GetNetlinkErrorCategory()
+{
+    static NetlinkErrorCategory instance;
+    return instance;
+}
+
 } // namespace Microsoft::Net::Netlink

src/linux/libnl-helpers/include/microsoft/net/netlink/NetlinkErrorCategory.hxx

@@ -42,26 +42,34 @@ struct NetlinkErrorCategory :
 
 /**
  * @brief Constructs a std::error_code from a netlink error code.
- * 
+ *
  * This function uses the std naming convention.
- * 
+ *
  * @param error The netlink error code. Must be positive.
- * @return std::error_code 
+ * @return std::error_code
  */
 [[nodiscard]] std::error_code
 make_netlink_error_code(int error);
 
 /**
  * @brief Alias for the make_netlink_error_code function.
- * 
+ *
  * This function uses the project naming convention.
- * 
- * @param error 
- * @return std::error_code 
+ *
+ * @param error
+ * @return std::error_code
  */
 [[nodiscard]] std::error_code
 MakeNetlinkErrorCode(int error);
 
+/**
+ * @brief Get the NetlinkErrorCategory object instance.
+ * 
+ * @return const NetlinkErrorCategory& 
+ */
+[[nodiscard]] const NetlinkErrorCategory&
+GetNetlinkErrorCategory();
+
 } // namespace Microsoft::Net::Netlink
 
 #endif // NETLINK_ERROR_CATEGORY_HXX

tests/unit/linux/libnl-helpers/CMakeLists.txt

@@ -6,6 +6,7 @@ target_sources(libnl-helpers-test-unit
         Main.cxx
         TestNetlink80211Interface.cxx
         TestNetlink80211ProtocolState.cxx
+        TestNetlinkException.cxx
         TestNetlinkRoute.cxx
 )
 

tests/unit/linux/libnl-helpers/TestNetlinkException.cxx

@@ -0,0 +1,14 @@
+
+#include <catch2/catch_test_macros.hpp>
+#include <microsoft/net/netlink/NetlinkException.hxx>
+#include <netlink/errno.h>
+
+TEST_CASE("NetlinkException", "[linux][libnl-helpers]")
+{
+    using Microsoft::Net::Netlink::NetlinkException;
+
+    SECTION("Does not crash")
+    {
+        REQUIRE_THROWS_AS(throw NetlinkException(NLE_BAD_SOCK, "test"), NetlinkException);
+    }
+}