QTcpSocket.readLine causing segmentation failure

[hasnain]

i am using QTcpsocket.readLine to read from a socket in a thread. it is working well otherwise but causing a segmentation failure. this the code:

Header file

#ifndef CLIENTTHREAD_H
#define CLIENTTHREAD_H
#include<QtNetwork/QTcpSocket>
#include<QThread>
 
class clientThread:public QThread
{
    Q_OBJECT
public:
    clientThread(QTcpSocket *,QObject *,QString);
   // MainWindow *m;
//    int index;
    QString name;
    void run();
signals:
    void updatechat(QString,QString);
private slots:
    void readFromClient();
private:
    QTcpSocket *socket;
};
 
#endif // CLIENTTHREAD_H

#ifndef CLIENTTHREAD_H
#define CLIENTTHREAD_H
#include<QtNetwork/QTcpSocket>
#include<QThread>

class clientThread:public QThread
{
    Q_OBJECT
public:
    clientThread(QTcpSocket *,QObject *,QString);
   // MainWindow *m;
//    int index;
    QString name;
    void run();
signals:
    void updatechat(QString,QString);
private slots:
    void readFromClient();
private:
    QTcpSocket *socket;
};

#endif // CLIENTTHREAD_H

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Source File;

#include "clientthread.h"
 
clientThread::clientThread(QTcpSocket *_socket,QObject *parent,/*int _index*/QString _name):QThread(parent),
socket(_socket),name(_name)
{
    connect(socket,SIGNAL(disconnected()),this,SLOT(terminate()));
}
 
void clientThread::run(){
 
    char *data;
    QString s;
    uint i;
    i=1024;
    qDebug()<<"client thread started";
 
}
 
void clientThread::readFromClient(){
    char *data;
    QString s;
    uint i;
    i=1024;
   [COLOR="Red"] socket->readLine(data,i);[/COLOR] 
    emit updatechat(tr(data),name);
}

#include "clientthread.h"

clientThread::clientThread(QTcpSocket *_socket,QObject *parent,/*int _index*/QString _name):QThread(parent),
socket(_socket),name(_name)
{
    connect(socket,SIGNAL(disconnected()),this,SLOT(terminate()));
}

void clientThread::run(){

    char *data;
    QString s;
    uint i;
    i=1024;
    qDebug()<<"client thread started";

}

void clientThread::readFromClient(){
    char *data;
    QString s;
    uint i;
    i=1024;
   [COLOR="Red"] socket->readLine(data,i);[/COLOR] 
    emit updatechat(tr(data),name);
}

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Any Ideas why this is happening.
Please help

[tbscope]

char *data;
socket->readLine(data,i);

Of course this crashes. What does data point to?