[FIXED] Invalidate stream state on recovery if tracking states mismatch

Signed-off-by: Maurice van Veen <github@mauricevanveen.com>

server/filestore.go

@@ -1739,6 +1739,7 @@ func (fs *fileStore) recoverFullState() (rerr error) {
 	var matched bool
 	mb := fs.lmb
 	if mb == nil || mb.index != blkIndex {
+		os.Remove(fn)
 		fs.warn("Stream state block does not exist or index mismatch")
 		return errCorruptState
 	}
@@ -1777,6 +1778,14 @@ func (fs *fileStore) recoverFullState() (rerr error) {
 		}
 	}
 
+	// We check first and last seq and number of msgs and bytes. If there is a difference,
+	// return and error so we rebuild from the message block state on disk.
+	if !trackingStatesEqual(&fs.state, &mstate) {
+		os.Remove(fn)
+		fs.warn("Stream state encountered internal inconsistency on recover")
+		return errCorruptState
+	}
+
 	return nil
 }
 

server/filestore_test.go

@@ -22,6 +22,7 @@ import (
 	"crypto/hmac"
 	crand "crypto/rand"
 	"crypto/sha256"
+	"encoding/binary"
 	"encoding/hex"
 	"encoding/json"
 	"errors"
@@ -8111,3 +8112,35 @@ func TestFileStoreWriteFullStateDetectCorruptState(t *testing.T) {
 	require_Equal(t, ss.LastSeq, 10)
 	require_Equal(t, ss.Msgs, 9)
 }
+
+func TestFileStoreRecoverFullStateDetectCorruptState(t *testing.T) {
+	fs, err := newFileStore(
+		FileStoreConfig{StoreDir: t.TempDir()},
+		StreamConfig{Name: "zzz", Subjects: []string{"foo.*"}, Storage: FileStorage})
+	require_NoError(t, err)
+	defer fs.Stop()
+
+	msg := []byte("abc")
+	for i := 1; i <= 10; i++ {
+		_, _, err = fs.StoreMsg(fmt.Sprintf("foo.%d", i), nil, msg)
+		require_NoError(t, err)
+	}
+
+	err = fs.writeFullState()
+	require_NoError(t, err)
+
+	sfile := filepath.Join(fs.fcfg.StoreDir, msgDir, streamStreamStateFile)
+	buf, err := os.ReadFile(sfile)
+	require_NoError(t, err)
+	// Update to an incorrect message count.
+	binary.PutUvarint(buf[2:], 0)
+	// Just append a corrected checksum to the end to make it pass the checks.
+	fs.hh.Reset()
+	fs.hh.Write(buf)
+	buf = fs.hh.Sum(buf)
+	err = os.WriteFile(sfile, buf, defaultFilePerms)
+	require_NoError(t, err)
+
+	err = fs.recoverFullState()
+	require_Error(t, err, errCorruptState)
+}