trx0trx.c, trx0trx.h:

  If MySQL wrote to its binlog, but for some reason trx->update_undo and trx->insert_undo were NULL in InnoDB, then trx->commit_lsn was garbage, and InnoDB could assert in the log flush of trx_commit_complete_for_mysql() (Bug #9277)

innobase/include/trx0trx.h

@@ -346,6 +346,12 @@ struct trx_struct{
 					in MySQL's binlog write, we will
 					flush the log to disk later in
 					a separate call */
+	ibool		must_flush_log_later;/* this flag is set to TRUE in
+					trx_commit_off_kernel() if
+					flush_log_later was TRUE, and there
+					were modifications by the transaction;
+					in that case we must flush the log
+					in trx_commit_complete_for_mysql() */
 	dulint		commit_lsn;	/* lsn at the time of the commit */
 	ibool		dict_operation;	/* TRUE if the trx is used to create
 					a table, create an index, or drop a

innobase/trx/trx0trx.c

@@ -96,6 +96,7 @@ trx_create(
 	trx->check_unique_secondary = TRUE;
 
 	trx->flush_log_later = FALSE;
+	trx->must_flush_log_later = FALSE;
 
 	trx->dict_operation = FALSE;
 
@@ -635,6 +636,8 @@ trx_commit_off_kernel(
 
 	rseg = trx->rseg;
 
+	trx->must_flush_log_later = FALSE;
+	
 	if (trx->insert_undo != NULL || trx->update_undo != NULL) {
 
 		mutex_exit(&kernel_mutex);
@@ -798,6 +801,7 @@ trx_commit_off_kernel(
 
                 if (trx->flush_log_later) {
                         /* Do nothing yet */
+			trx->must_flush_log_later = TRUE;
                 } else if (srv_flush_log_at_trx_commit == 0) {
                         /* Do nothing */
                 } else if (srv_flush_log_at_trx_commit == 1) {
@@ -1516,7 +1520,9 @@ trx_commit_complete_for_mysql(
 	
 	trx->op_info = (char*)"flushing log";
 
-        if (srv_flush_log_at_trx_commit == 0) {
+	if (!trx->must_flush_log_later) {
+		/* Do nothing */
+	} if (srv_flush_log_at_trx_commit == 0) {
                 /* Do nothing */
         } else if (srv_flush_log_at_trx_commit == 1) {
                 if (srv_unix_file_flush_method == SRV_UNIX_NOSYNC) {
@@ -1538,6 +1544,8 @@ trx_commit_complete_for_mysql(
                 ut_error;
         }
 
+	trx->must_flush_log_later = FALSE;
+
 	trx->op_info = (char*)"";
 
         return(0);