fixed a crash happening on incomplete inbound SNMP message

4 files changed, 14 insertions, 27 deletions

diff --git a/pysnmp/proto/mpmod/rfc2576.py b/pysnmp/proto/mpmod/rfc2576.py
index 39442cff..1a0b3cf1 100644
--- a/pysnmp/proto/mpmod/rfc2576.py
+++ b/pysnmp/proto/mpmod/rfc2576.py
@@ -247,13 +247,7 @@ class SnmpV1MessageProcessingModel(AbstractMessageProcessingModel):
         mibBuilder = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder
 
         # rfc3412: 7.2.2
-        try:
-            msg, restOfWholeMsg = decoder.decode(wholeMsg, asn1Spec=self._snmpMsgSpec)
-        except PyAsn1Error:
-            debug.logger & debug.flagMP and debug.logger('prepareDataElements: %s' % (sys.exc_info()[1],))
-            snmpInASNParseErrs, = mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')
-            snmpInASNParseErrs.syntax += 1
-            raise error.StatusInformation(errorIndication=errind.parseError)
+        msg, restOfWholeMsg = decoder.decode(wholeMsg, asn1Spec=self._snmpMsgSpec)
 
         debug.logger & debug.flagMP and debug.logger('prepareDataElements: %s' % (msg.prettyPrint(),))
 
diff --git a/pysnmp/proto/mpmod/rfc3412.py b/pysnmp/proto/mpmod/rfc3412.py
index 9f60c57e..4636f779 100644
--- a/pysnmp/proto/mpmod/rfc3412.py
+++ b/pysnmp/proto/mpmod/rfc3412.py
@@ -469,14 +469,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
     def prepareDataElements(self, snmpEngine, transportDomain,
                             transportAddress, wholeMsg):
         # 7.2.2
-        try:
-            msg, restOfwholeMsg = decoder.decode(wholeMsg, asn1Spec=self._snmpMsgSpec)
-
-        except PyAsn1Error:
-            debug.logger & debug.flagMP and debug.logger('prepareDataElements: %s' % (sys.exc_info()[1],))
-            snmpInASNParseErrs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')
-            snmpInASNParseErrs.syntax += 1
-            raise error.StatusInformation(errorIndication=errind.parseError)
+        msg, restOfwholeMsg = decoder.decode(wholeMsg, asn1Spec=self._snmpMsgSpec)
 
         debug.logger & debug.flagMP and debug.logger('prepareDataElements: %s' % (msg.prettyPrint(),))
 
diff --git a/pysnmp/proto/rfc3412.py b/pysnmp/proto/rfc3412.py
index d282279a..ad7d55f2 100644
--- a/pysnmp/proto/rfc3412.py
+++ b/pysnmp/proto/rfc3412.py
@@ -6,6 +6,7 @@
 #
 import sys
 from pyasn1.compat.octets import null
+from pyasn1.error import PyAsn1Error
 from pysnmp.smi import builder, instrum
 from pysnmp.proto import errind, error, cache
 from pysnmp.proto.api import verdec  # XXX
@@ -344,6 +345,13 @@ class MsgAndPduDispatcher(object):
                 )
             return restOfWholeMsg
 
+        except PyAsn1Error:
+            debug.logger & debug.flagMP and debug.logger('receiveMessage: %s' % (sys.exc_info()[1],))
+            snmpInASNParseErrs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')
+            snmpInASNParseErrs.syntax += 1
+
+            return restOfWholeMsg
+
         debug.logger & debug.flagDsp and debug.logger('receiveMessage: PDU %s' % PDU.prettyPrint())
 
         # 4.2.2
diff --git a/pysnmp/proto/secmod/rfc3414/service.py b/pysnmp/proto/secmod/rfc3414/service.py
index d2ee6250..4d7500b4 100644
--- a/pysnmp/proto/secmod/rfc3414/service.py
+++ b/pysnmp/proto/secmod/rfc3414/service.py
@@ -543,16 +543,9 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
             'processIncomingMsg: securityParameters %s' % debug.hexdump(securityParameters))
 
         # 3.2.1
-        try:
-            securityParameters, rest = decoder.decode(
-                securityParameters, asn1Spec=self.__securityParametersSpec
-            )
-
-        except PyAsn1Error:
-            debug.logger & debug.flagSM and debug.logger('processIncomingMsg: %s' % (sys.exc_info()[1],))
-            snmpInASNParseErrs, = mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')
-            snmpInASNParseErrs.syntax += 1
-            raise error.StatusInformation(errorIndication=errind.parseError)
+        securityParameters, rest = decoder.decode(
+            securityParameters, asn1Spec=self.__securityParametersSpec
+        )
 
         debug.logger & debug.flagSM and debug.logger('processIncomingMsg: %s' % (securityParameters.prettyPrint(),))
 
@@ -936,8 +929,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
                 )
             scopedPduSpec = scopedPduData.setComponentByPosition(0).getComponentByPosition(0)
             try:
-                scopedPDU, rest = decoder.decode(decryptedData,
-                                                 asn1Spec=scopedPduSpec)
+                scopedPDU, rest = decoder.decode(decryptedData, asn1Spec=scopedPduSpec)
 
             except PyAsn1Error:
                 debug.logger & debug.flagSM and debug.logger(