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[9.2](backport #48031) filebeat: Fix scenarios for short message and invalid month number in syslog messages #48038

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Merged
bhapas merged 2 commits into from
Dec 11, 2025
Merged

[9.2](backport #48031) filebeat: Fix scenarios for short message and invalid month number in syslog messages #48038

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208fa27
filebeat: Fix scenarios for short message and invalid month number in…
bhapas Dec 11, 2025
7f0a581
Merge branch '9.2' into mergify/bp/9.2/pr-48031
bhapas Dec 11, 2025
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19 changes: 9 additions & 10 deletions filebeat/input/syslog/event.go
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ var month = map[string]time.Month{
"Dec": time.December,
}

var monthIndexed = []time.Month{
var monthIndexed = [...]time.Month{
0,
time.January,
time.February,
Expand Down Expand Up @@ -117,7 +117,7 @@ func (s *event) SetTimeZone(b []byte) {
}

// +00 +00:00 or +0000
// Use second value directly and don't use unecessary time.Duration.
// Use second value directly and don't use unnecessary time.Duration.
// Time.FixedZone accepts number of seconds.
var h, m int
switch len(b[1:]) {
Expand All @@ -137,7 +137,10 @@ func (s *event) SetTimeZone(b []byte) {

// SetMonthNumeric sets the month with a number.
func (s *event) SetMonthNumeric(b []byte) {
s.month = monthIndexed[bytesToInt(skipLeadZero(b))]
month := bytesToInt(skipLeadZero(b))
if month < len(monthIndexed) {
s.month = monthIndexed[month]
}
}

// SetMonth sets the month.
Expand Down Expand Up @@ -211,12 +214,8 @@ func (s *event) Year() int {

// SetMessage sets the message.
func (s *event) SetMessage(b []byte) {
// remove BOM
if b[0] == 0xef && b[1] == 0xbb && b[2] == 0xbf {
s.message = string(b[3:])
} else {
s.message = string(b)
}
// Trim BOM: https://unicode.org/faq/utf_bom#bom5
s.message = string(bytes.TrimPrefix(b, []byte("\ufeff")))
}

// Message returns the message.
Expand Down Expand Up @@ -262,7 +261,7 @@ func (s *event) SetHostname(b []byte) {

// Hostname returns the hostname.
func (s *event) Hostname() string {
return string(s.hostname)
return s.hostname
}

// SetProgram sets the programs as a byte slice.
Expand Down
10 changes: 10 additions & 0 deletions filebeat/input/syslog/rfc3164_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -796,6 +796,16 @@ func TestPriority(t *testing.T) {
}
}

func TestParserRFC3164InvalidMonthNumeric(t *testing.T) {
event := newEvent()
ParserRFC3164([]byte("0000-20-"), event)
}

func TestParserRFC3164ShortMessage(t *testing.T) {
event := newEvent()
ParserRFC3164([]byte("Oct 1 00:00:00 \xef"), event)
}

var e *event

func BenchmarkParserRFC3164r(b *testing.B) {
Expand Down