c - Why the pointer's value changes in multi-thread malloc?

Question

1. Hi guys, I get a very odd problem here. Do u have any idea about the segmentation fault? Any advice would be appreciated! Thx in advance!

Test()

{

pMsg_node = found_bakup_msg_node();

if(pMsg_node != NULL) {
    Dprintf("#%s#%d %p\n", __FUNCTION__, __LINE__, pMsg_node); 
    ret = cp_msg_node_data(pMsg_node, pMsg_next);
}

}

===================================================================

struct MSG_INFO* found_bakup_msg_node(void) { struct MSG_INFO* msg_node = NULL;

    msg_node = (struct MSG_INFO*)malloc(sizeof(struct MSG_INFO));
    if(msg_node != NULL) {
            memset(msg_node, 0x0, sizeof(struct MSG_INFO));

            Dprintf("#%s# %p\n", __FUNCTION__,
                             msg_node);
    }

    return msg_node;

}

========================================================

---------------------------LOG 1--------------------------------

> header=0x923950    
>found_bakup_msg_node#alloc_bakup_count=1 0x7f6090032f70 //return from malloc() 
>cp_msg_list#561
> cp_msg_node_data#458   
>cp_msg_node_data#463 0xffffffff90032f70  0x923950  //notice here
>Segmentation fault
> robin@robin-desktop:/media/work/project/rcd$    

--------------------------LOG 2 --------------------------------

 #cp_msg_list#566
#found_bakup_msg_node#alloc_bakup_count=180 **0x7fe6e000d5b0**
#cp_msg_node_data#464 **0xffffffffe000d5b0** 0x2154620
Segmentation fault
robin@robin-desktop:/media/work/project/rcd$

---

Answer 1

你试过在gdb下运行程序吗？它通常会显示您遇到分段错误的原因，并且通常有助于学习如何使用 gdb。