fix(mempool): data race in clist_mempool during async recheck

+ fixed callback invocation in unsync_local_client during CheckTxAsync

Author: kakysha

abci/client/unsync_local_client.go

@@ -47,14 +47,12 @@ func (app *unsyncLocalClient) CheckTxAsync(ctx context.Context, req *types.Reque
 	reqres := NewReqRes(types.ToRequestCheckTx(req))
 
 	go func() {
-		res, err := app.Application.CheckTx(ctx, req)
+		res, _ := app.Application.CheckTx(ctx, req)
+		reqres.Response = types.ToResponseCheckTx(res)
 
-		if err != nil {
-			// reqres.Response = types.ToResponseException(err.Error()) // don't think this is needed
-			return
+		if app.Callback != nil {
+			app.Callback(reqres.Request, reqres.Response)
 		}
-
-		reqres.Response = types.ToResponseCheckTx(res)
 		reqres.InvokeCallback()
 	}()
 

mempool/clist_mempool.go

@@ -55,6 +55,8 @@ type CListMempool struct {
 
 	logger  log.Logger
 	metrics *Metrics
+
+	recheckCbMux cmtsync.Mutex
 }
 
 var _ Mempool = &CListMempool{}
@@ -478,6 +480,8 @@ func (mem *CListMempool) resCbFirstTime(
 // The case where the app checks the tx for the first time is handled by the
 // resCbFirstTime callback.
 func (mem *CListMempool) resCbRecheck(tx types.Tx, res *abci.ResponseCheckTx) {
+	mem.recheckCbMux.Lock()
+	defer mem.recheckCbMux.Unlock()
 	// Check whether tx is still in the list of transactions that can be rechecked.
 	if !mem.recheck.findNextEntryMatching(&tx) {
 		// Reached the end of the list and didn't find a matching tx; rechecking has finished.