util-decode-der: fix hang detected by AFL

Fix hang that occurs when child->length is zero, resulting in an
endless loop.

diff --git a/src/util-decode-der.c b/src/util-decode-der.c
index f97497665f77aa86a427e8f1df4907d5e19a770d..be56b5e546f7589d3af864963536f2542a27fb47 100644 (file)
--- a/src/util-decode-der.c
+++ b/src/util-decode-der.c
@@ -270,6 +270,12 @@ static Asn1Generic * DecodeAsn1DerGeneric(const unsigned char *buffer,
     if (child == NULL)
         return NULL;
 
+    /* child length should never be zero */
+    if (child->length == 0) {
+        SCFree(child);
+        return NULL;
+    }
+
     child->header = el;
     return child;
 }