dnp3: adds bounds check for prefix chararray

Ticket: #4558
Avoids intra structure overflow

(cherry picked from commit 126a7dcb4f1818a806c882c54da864992bb304d5)

diff --git a/scripts/dnp3-gen/dnp3-gen.py b/scripts/dnp3-gen/dnp3-gen.py
index 19076e7799716aa7abc5b74b9f7b6b4e7030539d..701cfd2e688806a20f21419c0c56e9b800dfbd0e 100755 (executable)
--- a/scripts/dnp3-gen/dnp3-gen.py
+++ b/scripts/dnp3-gen/dnp3-gen.py
@@ -524,6 +524,9 @@ static int DNP3DecodeObjectG{{object.group}}V{{object.variation}}(const uint8_t
         }
 {% elif field.type == "chararray" %}
 {% if field.len_from_prefix %}
+        if (prefix - (offset - *len) >= {{field.size}}) {
+            goto error;
+        }
         object->{{field.len_field}} = prefix - (offset - *len);
 {% endif %}
         if (object->{{field.len_field}} > 0) {