core: better support of Buf with fixed size but invalid content

jewalt · Mar 17, 2021 · 80aaf07 · 80aaf07
1 parent a20d9eb
commit 80aaf07
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Showing 2 changed files with 24 additions and 3 deletions.
diff --git a/pycrate_core/base.py b/pycrate_core/base.py
@@ -297,6 +297,8 @@ def get_bl(self):
     __call__ = get_val
 
 
+# Null terminated string
+# only different from Buf when consuming a buffer at parsing
 class NullTermStr(Buf):
 
     def _from_char(self, char):

diff --git a/pycrate_core/elt.py b/pycrate_core/elt.py
@@ -32,6 +32,8 @@
            'Element', 'Atom', 'Envelope', 'Array', 'Sequence', 'Alt']
 
 
+from binascii import hexlify
+
 try:
     from json import JSONEncoder, JSONDecoder
 except ImportError:
@@ -660,7 +662,13 @@ def to_uint(self):
         Returns:
             uint (int) : unsigned integer
         """
-        return bytes_to_uint(self.to_bytes(), self.get_bl())
+        try:
+            return bytes_to_uint(self.to_bytes(), self.get_bl())
+        except PycrateErr:
+            # an invalid value has been set, _SAFE_STAT / DYN is probably disabled
+            # for e.g. fuzzing purpose, but there is still need to not break here
+            b = self.to_bytes()
+            return bytes_to_uint(b, len(b)<<3)
 
     def from_int(self, integ, bl=None):
         """Consume a signed integer or charpy instance `integ' and sets the 
@@ -698,7 +706,13 @@ def to_int(self):
         Returns:
             integ (int) : signed integer
         """
-        return bytes_to_int(self.to_bytes(), self.get_bl())
+        try:
+            return bytes_to_int(self.to_bytes(), self.get_bl())
+        except PycrateErr:
+            # an invalid value has been set, _SAFE_STAT / DYN is probably disabled
+            # for e.g. fuzzing purpose, but there is still need to not break here
+            b = self.to_bytes()
+            return bytes_to_int(b, len(b)<<3)
 
     if python_version < 3:
         __str__ = to_bytes
@@ -725,7 +739,12 @@ def hex(self):
         if bl == 0:
             return ''
         else:
-            return uint_to_hex(bytes_to_uint(self.to_bytes(), bl), bl)
+            try:
+                return uint_to_hex(bytes_to_uint(self.to_bytes(), bl), bl)
+            except PycrateErr:
+                # an invalid value has been set, _SAFE_STAT / DYN is probably disabled
+                # for e.g. fuzzing purpose, but there is still need to not break here
+                return hexlify(self.to_bytes()).decode('ascii')
 
     __bin__ = bin
     __hex__ = hex