Remove --no-undefined in SAN builds (#1562)

cmake/ccf_app.cmake

@@ -257,7 +257,9 @@ function(add_ccf_app name)
       ${virt_name} PRIVATE ${PARSED_ARGS_LINK_LIBS_VIRTUAL} ccf.virtual
     )
 
-    target_link_options(${virt_name} PRIVATE LINKER:--no-undefined)
+    if(NOT SAN)
+      target_link_options(${virt_name} PRIVATE LINKER:--no-undefined)
+    endif()
 
     set_property(TARGET ${virt_name} PROPERTY POSITION_INDEPENDENT_CODE ON)
 

cmake/common.cmake

@@ -79,6 +79,13 @@ set(CLIENT_MBEDTLS_LIBRARIES "${MBEDTLS_LIBRARIES}")
 include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/ccf_app.cmake)
 install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/cmake/ccf_app.cmake DESTINATION cmake)
 
+if(SAN AND LVI_MITIGATIONS)
+  message(
+    FATAL_ERROR
+      "Building with both SAN and LVI mitigations is unsafe and deadlocks - choose one"
+  )
+endif()
+
 add_custom_command(
   COMMAND
     openenclave::oeedger8r ${CCF_DIR}/edl/ccf.edl --search-path ${OE_INCLUDEDIR}