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Fix panic on malformed SFlow packets #1228

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Fix panic on malformed SFlow packets #1228

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12 changes: 11 additions & 1 deletion layers/sflow.go
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Original file line number Diff line number Diff line change
Expand Up @@ -300,9 +300,16 @@ func (s SFlowIPType) Length() int {
func (s *SFlowDatagram) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
var agentAddressType SFlowIPType

if len(data) < 8 {
return fmt.Errorf("SFlow Datagram too short: %d bytes", len(data))
}
data, s.DatagramVersion = data[4:], binary.BigEndian.Uint32(data[:4])
data, agentAddressType = data[4:], SFlowIPType(binary.BigEndian.Uint32(data[:4]))
data, s.AgentAddress = data[agentAddressType.Length():], data[:agentAddressType.Length()]
agentLen := agentAddressType.Length()
if len(data) < int(agentLen)+16 {
return fmt.Errorf("SFlow Datagram too short for agent address and header fields")
}
data, s.AgentAddress = data[agentLen:], data[:agentLen]
data, s.SubAgentID = data[4:], binary.BigEndian.Uint32(data[:4])
data, s.SequenceNumber = data[4:], binary.BigEndian.Uint32(data[:4])
data, s.AgentUptime = data[4:], binary.BigEndian.Uint32(data[:4])
Expand All @@ -312,6 +319,9 @@ func (s *SFlowDatagram) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback)
return fmt.Errorf("SFlow Datagram has invalid sample length: %d", s.SampleCount)
}
for i := uint32(0); i < s.SampleCount; i++ {
if len(data) < 4 {
return fmt.Errorf("SFlow Datagram too short for sample %d header", i)
}
sdf := SFlowDataFormat(binary.BigEndian.Uint32(data[:4]))
_, sampleType := sdf.decode()
switch sampleType {
Expand Down