Core dump when using RedisSyncClient::command

[SnowfallDan]

hi

i am facing a core dump when call RedisSyncClient::command() function.

My env :
boost: 1.7.0
gcc: 6.3.0
os: centos 7.6

gdb's bt:
(gdb) bt
#0 0x00007f46f5e1295f in __memmove_ssse3_back () from /lib64/libc.so.6
#1 0x000000000055151d in redisclient::RedisClientImpl::syncReadResponse(boost::posix_time::time_duration const&, boost::system::error_code&) ()
#2 0x000000000055137f in redisclient::RedisClientImpl::doSyncCommand(std::deque<redisclient::RedisBuffer, std::allocatorredisclient::RedisBuffer > const&, boost::posix_time::time_duration const&, boost::system::error_code&) ()
#3 0x0000000000552028 in redisclient::RedisSyncClient::command(std::string, std::deque<redisclient::RedisBuffer, std::allocatorredisclient::RedisBuffer >, boost::system::error_code&) ()
#4 0x0000000000551eef in redisclient::RedisSyncClient::command(std::string, std::deque<redisclient::RedisBuffer, std::allocatorredisclient::RedisBuffer >)()

Source code:
`
long get_update_remain(const void *sql_ctx, const void *redis_ctx, const char *user_id, unsigned int flow_size)
{
long remain_k = 0;
string key_remain_size = string(KEY_ORDER_REMAIN_SIZE) + user_id;

assert(redis_ctx);
auto redis = (redisclient::RedisSyncClient *) redis_ctx;

redisclient::RedisValue result;
result = redis->command("GET", {key_remain_size});
string res = result.toString();
if (result.isError() || result.toString().empty())
{
    printf("GET error, key[%s], result[%s]\n",
           key_remain_size.c_str(), result.toString().c_str());

    //select new order
    if (!select_order(sql_ctx, redis_ctx, user_id))
    {
        return 0;
    }
}
else
{
    try
    {
        printf("%s\n", result.toString().c_str());
        remain_k = std::stol(result.toString());
        printf("before DECRBY remain_k is %ld\n", remain_k);
    }
    catch (...)
    {
        printf("error");
    }
}

if(flow_size == 0)
    return remain_k;

//Redis Dec
result = redis->command("DECRBY", {key_remain_size, std::to_string(flow_size/1024)});
if (result.isError() || !result.isInt())
{
    printf("DECRBY key=%s error\n", key_remain_size.c_str());
    return 0;
}
remain_k = (long)result.toInt();
printf("after DECRBY remain_k is %ld\n", remain_k);

if (remain_k<=0)
    unset_order(sql_ctx, redis_ctx, user_id);

return remain_k;

}`