From 88b9088499c38484acc13b77792c42be8158c173 Mon Sep 17 00:00:00 2001
From: XLONG96 <1073501156@qq.com>
Date: Thu, 29 Feb 2024 21:31:54 +0800
Subject: [PATCH] lib/logstorage: avoid panic when parsing regex with stream
 filter (#5897)

---
 lib/logstorage/parser.go        |  8 ++++++++
 lib/logstorage/stream_filter.go | 14 +-------------
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/lib/logstorage/parser.go b/lib/logstorage/parser.go
index d0f66c898e..104491a018 100644
--- a/lib/logstorage/parser.go
+++ b/lib/logstorage/parser.go
@@ -12,6 +12,7 @@ import (
 	"unicode/utf8"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promutils"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/regexutil"
 )
 
 type lexer struct {
@@ -1070,6 +1071,13 @@ func parseStreamTagFilter(lex *lexer) (*streamTagFilter, error) {
 		op:      op,
 		value:   value,
 	}
+	if op == "=~" || op == "!~" {
+		re, err := regexutil.NewPromRegex(value)
+		if err != nil {
+			return nil, fmt.Errorf("invalid regexp %q for stream filter: %w", value, err)
+		}
+		stf.regexp = re
+	}
 	return stf, nil
 }
 
diff --git a/lib/logstorage/stream_filter.go b/lib/logstorage/stream_filter.go
index 838e95ed03..0cce172295 100644
--- a/lib/logstorage/stream_filter.go
+++ b/lib/logstorage/stream_filter.go
@@ -3,11 +3,9 @@ package logstorage
 import (
 	"strconv"
 	"strings"
-	"sync"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/regexutil"
 )
 
@@ -68,23 +66,13 @@ type streamTagFilter struct {
 	// value is the value
 	value string
 
-	regexpOnce sync.Once
-	regexp     *regexutil.PromRegex
+	regexp *regexutil.PromRegex
 }
 
 func (tf *streamTagFilter) getRegexp() *regexutil.PromRegex {
-	tf.regexpOnce.Do(tf.initRegexp)
 	return tf.regexp
 }
 
-func (tf *streamTagFilter) initRegexp() {
-	re, err := regexutil.NewPromRegex(tf.value)
-	if err != nil {
-		logger.Panicf("BUG: cannot parse regexp %q: %s", tf.value, err)
-	}
-	tf.regexp = re
-}
-
 func (tf *streamTagFilter) String() string {
 	return quoteTokenIfNeeded(tf.tagName) + tf.op + strconv.Quote(tf.value)
 }