Fix to CER/DER Boolean decoder - fail on non single-octet payload.

Thanks to Alex Gaynor for pointing out!

3 files changed, 14 insertions, 3 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 90bd1fc..9f4c647 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -5,6 +5,7 @@ Revision 0.1.9
 - Extensions added to text files, CVS attic flushed.
 - Fix to make uninitilaized pyasn1 objects failing properly on hash().
 - Fix to ObjectIdentifier initialization from unicode string.
+- Fix to CER/DER Boolean decoder - fail on non single-octet payload.
 
 Revision 0.1.8, released 22-06-2015
 -----------------------------------
diff --git a/pyasn1/codec/cer/decoder.py b/pyasn1/codec/cer/decoder.py
index 9fd37c1..1770cd8 100644
--- a/pyasn1/codec/cer/decoder.py
+++ b/pyasn1/codec/cer/decoder.py
@@ -9,8 +9,8 @@ class BooleanDecoder(decoder.AbstractSimpleDecoder):
     def valueDecoder(self, fullSubstrate, substrate, asn1Spec, tagSet, length,
                      state, decodeFun, substrateFun):
         head, tail = substrate[:length], substrate[length:]
-        if not head:
-            raise error.PyAsn1Error('Empty substrate')
+        if not head or length != 1:
+            raise error.PyAsn1Error('Not single-octet Boolean payload')
         byte = oct2int(head[0])
         # CER/DER specifies encoding of TRUE as 0xFF and FALSE as 0x0, while
         # BER allows any non-zero value as TRUE; cf. sections 8.2.2. and 11.1 
@@ -20,7 +20,7 @@ class BooleanDecoder(decoder.AbstractSimpleDecoder):
         elif byte == 0x00:
             value = 0
         else:
-            raise error.PyAsn1Error('Boolean CER violation: %s' % byte)
+            raise error.PyAsn1Error('Unexpected Boolean payload: %s' % byte)
         return self._createComponent(asn1Spec, tagSet, value), tail
 
 tagMap = decoder.tagMap.copy()
diff --git a/test/codec/cer/test_decoder.py b/test/codec/cer/test_decoder.py
index 7195b72..9d793a3 100644
--- a/test/codec/cer/test_decoder.py
+++ b/test/codec/cer/test_decoder.py
@@ -17,6 +17,16 @@ class BooleanDecoderTestCase(unittest.TestCase):
         assert decoder.decode(ints2octs((1, 1, 255))) == (1, null)
     def testFalse(self):
         assert decoder.decode(ints2octs((1, 1, 0))) == (0, null)
+    def testEmpty(self):
+        try:
+            decoder.decode(ints2octs((1, 0)))
+        except PyAsn1Error:
+            pass
+    def testOverflow(self):
+        try:
+            decoder.decode(ints2octs((1, 2, 0, 0)))
+        except PyAsn1Error:
+            pass
         
 class OctetStringDecoderTestCase(unittest.TestCase):
     def testShortMode(self):