ddl, util/codec: fix add index OOM and prevent panic in logging (#29925)

ddl/backfilling.go

@@ -423,6 +423,13 @@ func (w *worker) handleReorgTasks(reorgInfo *reorgInfo, totalAddedCount *int64,
 }
 
 func tryDecodeToHandleString(key kv.Key) string {
+ defer func() {
+ if r := recover(); r != nil {
+ logutil.BgLogger().Warn("tryDecodeToHandleString panic",
+ zap.Any("recover()", r),
+ zap.Binary("key", key))
+ }
+ }()
  handle, err := tablecodec.DecodeRowKey(key)
  if err != nil {
  recordPrefixIdx := bytes.Index(key, []byte("_r"))

tablecodec/tablecodec_test.go

@@ -54,6 +54,20 @@ func (s *testTableCodecSuite) TestTableCodec(c *C) {
  c.Assert(h.IntValue(), Equals, int64(2))
 }
 
+// https://github.com/pingcap/tidb/issues/27687.
+func (s *testTableCodecSuite) TestTableCodecInvalid(c *C) {
+ tableID := int64(100)
+ buf := make([]byte, 0, 11)
+ buf = append(buf, 't')
+ buf = codec.EncodeInt(buf, tableID)
+ buf = append(buf, '_', 'r')
+ buf = codec.EncodeInt(buf, -9078412423848787968)
+ buf = append(buf, '0')
+ _, err := DecodeRowKey(buf)
+ c.Assert(err, NotNil)
+ c.Assert(err.Error(), Equals, "invalid encoded key")
+}
+
 // column is a structure used for test
 type column struct {
  id int64

util/codec/codec.go

@@ -961,7 +961,9 @@ func peek(b []byte) (length int, err error) {
  return 0, errors.Trace(err)
  }
  length += l
- if length > originLength {
+ if length <= 0 {
+ return 0, errors.New("invalid encoded key")
+ } else if length > originLength {
  return 0, errors.Errorf("invalid encoded key, "+
  "expected length: %d, actual length: %d", length, originLength)
  }