fixes to verify pyasn1 decoder.decode() return to withstand

broken SNMP messages or its components

3 files changed, 19 insertions, 4 deletions

diff --git a/pysnmp/proto/mpmod/rfc2576.py b/pysnmp/proto/mpmod/rfc2576.py
index 03ad11f..d71e08e 100644
--- a/pysnmp/proto/mpmod/rfc2576.py
+++ b/pysnmp/proto/mpmod/rfc2576.py
@@ -1,6 +1,6 @@
 # SNMP v1 & v2c message processing models implementation
 import sys
-from pyasn1.codec.ber import decoder
+from pyasn1.codec.ber import decoder, eoo
 from pyasn1.type import univ
 from pyasn1.compat.octets import null
 from pyasn1.error import PyAsn1Error
@@ -272,6 +272,11 @@ class SnmpV1MessageProcessingModel(AbstractMessageProcessingModel):
 
         debug.logger & debug.flagMP and debug.logger('prepareDataElements: %s' % (msg.prettyPrint(),))
 
+        if eoo.endOfOctets.isSameTypeWith(msg):
+            raise error.StatusInformation(
+                errorIndication=errind.parseError
+            )
+
         # rfc3412: 7.2.3
         msgVersion = messageProcessingModel = msg.getComponentByPosition(0)
 
diff --git a/pysnmp/proto/mpmod/rfc3412.py b/pysnmp/proto/mpmod/rfc3412.py
index 09779a4..8c58145 100644
--- a/pysnmp/proto/mpmod/rfc3412.py
+++ b/pysnmp/proto/mpmod/rfc3412.py
@@ -3,7 +3,7 @@ import sys
 from pysnmp.proto.mpmod.base import AbstractMessageProcessingModel
 from pysnmp.proto import rfc1905, rfc3411, api, errind, error
 from pyasn1.type import univ, namedtype, constraint
-from pyasn1.codec.ber import decoder
+from pyasn1.codec.ber import decoder, eoo
 from pyasn1.error import PyAsn1Error
 from pysnmp import debug
 
@@ -512,6 +512,11 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
 
         debug.logger & debug.flagMP and debug.logger('prepareDataElements: %s' % (msg.prettyPrint(),))
 
+        if eoo.endOfOctets.isSameTypeWith(msg):
+            raise error.StatusInformation(
+                errorIndication=errind.parseError
+            )
+
         # 7.2.3
         headerData = msg.getComponentByPosition(1)
         msgVersion = messageProcessingModel = msg.getComponentByPosition(0)
diff --git a/pysnmp/proto/secmod/rfc3414/service.py b/pysnmp/proto/secmod/rfc3414/service.py
index c50fc17..4a6affb 100644
--- a/pysnmp/proto/secmod/rfc3414/service.py
+++ b/pysnmp/proto/secmod/rfc3414/service.py
@@ -9,7 +9,7 @@ from pysnmp.smi.error import NoSuchInstanceError
 from pysnmp.proto import rfc1155, errind, error
 from pysnmp import debug
 from pyasn1.type import univ, namedtype, constraint
-from pyasn1.codec.ber import encoder, decoder
+from pyasn1.codec.ber import encoder, decoder, eoo
 from pyasn1.error import PyAsn1Error
 from pyasn1.compat.octets import null
     
@@ -612,10 +612,15 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
             snmpInASNParseErrs.syntax = snmpInASNParseErrs.syntax + 1
             raise error.StatusInformation(
                 errorIndication=errind.parseError
-                )
+            )
 
         debug.logger & debug.flagSM and debug.logger('processIncomingMsg: %s' % (securityParameters.prettyPrint(),))
 
+        if eoo.endOfOctets.isSameTypeWith(securityParameters):
+            raise error.StatusInformation(
+                errorIndication=errind.parseError
+            )
+
         # 3.2.2
         msgAuthoritativeEngineID = securityParameters.getComponentByPosition(0)
         securityStateReference = self._cache.push(