check_tso:make sure commit_ts > start_ts during commit in transaction (…

…pingcap#2901)

store/tikv/2pc.go

@@ -506,6 +506,15 @@ func (c *twoPhaseCommitter) execute() error {
 		log.Warnf("2PC get commitTS failed: %v, tid: %d", err, c.startTS)
 		return errors.Trace(err)
 	}
+
+	// check commitTS
+	if commitTS <= c.startTS {
+		err = errors.Errorf("Invalid transaction tso with start_ts=%v while commit_ts=%v",
+			c.startTS,
+			commitTS)
+		log.Error(err)
+		return errors.Trace(err)
+	}
 	c.commitTS = commitTS
 	if err := c.checkSchemaValid(); err != nil {
 		return errors.Trace(err)

store/tikv/2pc_test.go

@@ -14,6 +14,7 @@
 package tikv
 
 import (
+	"math"
 	"math/rand"
 	"strings"
 	"time"
@@ -286,3 +287,19 @@ func (c *slowClient) SendCopReq(ctx goctx.Context, addr string, req *coprocessor
 	}
 	return c.Client.SendCopReq(ctx, addr, req, timeout)
 }
+
+func (s *testCommitterSuite) TestIllegalTso(c *C) {
+	txn := s.begin(c)
+	data := map[string]string{
+		"name": "aa",
+		"age":  "12",
+	}
+	for k, v := range data {
+		err := txn.Set([]byte(k), []byte(v))
+		c.Assert(err, IsNil)
+	}
+	// make start ts bigger.
+	txn.startTS = uint64(math.MaxUint64)
+	err := txn.Commit()
+	c.Assert(err, NotNil)
+}