lib/bytesutil: make sure that the string passed to FastStringMather.Match() is copied before using it as a key in the internal cache map

This prevents from possible corruption of the internal cache map
when the underlying byte slice used by the string key is modified.

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3227

docs/CHANGELOG.md

@@ -46,6 +46,8 @@ The following tip changes can be tested by building VictoriaMetrics components f
 * BUGFIX: [vmbackup](https://docs.victoriametrics.com/vmbackup.html): set default region to `us-east-1` if `AWS_REGION` environment variable isn't set. The issue was introduced in [vmbackup v1.82.0](https://docs.victoriametrics.com/CHANGELOG.html#v1820). See [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/3224).
 * BUGFIX: [vmbackupmanager](https://docs.victoriametrics.com/vmbackupmanager.html): fix deletion of old backups at [Azure blob storage](https://azure.microsoft.com/en-us/products/storage/blobs/).
 * BUGFIX: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): properly merge buckets with identical `le` values, but with different string representation of these values when calculating [histogram_quantile](https://docs.victoriametrics.com/MetricsQL.html#histogram_quantile) and [histogram_share](https://docs.victoriametrics.com/MetricsQL.html#histogram_share). For example, `http_request_duration_seconds_bucket{le="5"}` and `http_requests_duration_seconds_bucket{le="5.0"}`. Such buckets may be returned from distinct targets. Thanks to @647-coder for the [pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/3225).
+* BUGFIX: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): properly apply regex filters when searching for time series. Previously unexpected time series could be returned from regex filter. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3227). The issue was introduced in [v1.82.0](https://docs.victoriametrics.com/CHANGELOG.html#v1820).
+* BUGFIX: [vmagent](https://docs.victoriametrics.com/vmbagent.html): properly apply `if` section with regex filters. Previously unexpected metrics could be returned from `if` section. The issue was introduced in [v1.82.0](https://docs.victoriametrics.com/CHANGELOG.html#v1820).
 
 ## [v1.82.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.82.0)
 

lib/bytesutil/fast_string_matcher.go

@@ -1,6 +1,7 @@
 package bytesutil
 
 import (
+	"strings"
 	"sync"
 	"sync/atomic"
 )
@@ -38,6 +39,11 @@ func (fsm *FastStringMatcher) Match(s string) bool {
 	// Slow path - run matchFunc for s and store the result in the cache.
 	b := fsm.matchFunc(s)
 	bp := &b
+	// Make a copy of s in order to limit memory usage to the s length,
+	// since the s may point to bigger string.
+	// This also protects from the case when s contains unsafe string, which points to a temporary byte slice.
+	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3227
+	s = strings.Clone(s)
 	m.Store(s, bp)
 	n := atomic.AddUint64(&fsm.mLen, 1)
 	if n > 100e3 {

lib/bytesutil/fast_string_transformer.go

@@ -40,6 +40,8 @@ func (fst *FastStringTransformer) Transform(s string) string {
 	sTransformed := fst.transformFunc(s)
 	// Make a copy of s in order to limit memory usage to the s length,
 	// since the s may point to bigger string.
+	// This also protects from the case when s contains unsafe string, which points to a temporary byte slice.
+	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3227
 	s = strings.Clone(s)
 	if sTransformed == s {
 		// point sTransformed to just allocated s, since it may point to s,