Do not try to write over null values

diff --git a/lib/element.c b/lib/element.c
index ee77feb..8addf02 100644 (file)
--- a/lib/element.c
+++ b/lib/element.c
@@ -621,7 +621,8 @@ asn1_write_value (asn1_node node_root, const char *name,
        if (ptr_size < data_size) { \
                return ASN1_MEM_ERROR; \
        } else { \
-               memcpy( ptr, data, data_size); \
+               if (ptr) \
+                 memcpy( ptr, data, data_size); \
        }
 
 #define PUT_STR_VALUE( ptr, ptr_size, data) \
@@ -630,7 +631,8 @@ asn1_write_value (asn1_node node_root, const char *name,
                return ASN1_MEM_ERROR; \
        } else { \
                /* this strcpy is checked */ \
-               _asn1_strcpy(ptr, data); \
+               if (ptr) \
+                 _asn1_strcpy(ptr, data); \
        }
 
 #define PUT_AS_STR_VALUE( ptr, ptr_size, data, data_size) \
@@ -639,8 +641,10 @@ asn1_write_value (asn1_node node_root, const char *name,
                return ASN1_MEM_ERROR; \
        } else { \
                /* this strcpy is checked */ \
-               memcpy(ptr, data, data_size); \
-               ptr[data_size] = 0; \
+               if (ptr) { \
+                 memcpy(ptr, data, data_size); \
+                 ptr[data_size] = 0; \
+               } \
        }
 
 #define ADD_STR_VALUE( ptr, ptr_size, data) \
@@ -649,7 +653,7 @@ asn1_write_value (asn1_node node_root, const char *name,
                return ASN1_MEM_ERROR; \
        } else { \
                /* this strcat is checked */ \
-               _asn1_strcat(ptr, data); \
+               if (ptr) _asn1_strcat(ptr, data); \
        }
 
 /**