Valgrind报uninitialized value was created by a heap allocation

程序运行正常，可是在测memery leak的时候报上面那个错，具体错误消息如下：
==25663== Conditional jump or move depends on uninitialised value(s)
==25663== at 0x400C9F: add_edge (graph.c:59)
==25663== by 0x40071A: main (main.c:13)
==25663== Uninitialised value was created by a heap allocation
==25663== at 0x4A0515D: malloc (vg_replace_malloc.c:195)
==25663== by 0x400A80: add_vertex (graph.c:22)
==25663== by 0x400DF8: add_edge (graph.c:84)
==25663== by 0x40071A: main (main.c:13)

我的程序用链接表构建一个无向图来解决TSP的. 
graph.c:22
for(adj_v=(*vp)->adj_list; adj_v->next!=NULL; adj_v=adj_v->next);
adj_v->next = (adj_vertex_t *)malloc(sizeof(adj_vertex_t));
adj_v=adj_v->next;
adj_v->edge_weight=weight;
我这个该怎么初始化新alloc的memery space呢？因为我马上要加新的节点信息到这个地方了，看起来应该没问题啊？C语言不太好，请大牛指教

memset(adj_v->next,0,sizeof(adj_vertex_t));

所有报错的地方都是循环语句，类似于
for(vp = *vtxhead; vp != NULL; vp = vp->next){

是不是说最后vp->next是NULL的时候，Valgrind误认为是uninitialized value,如果是这个问题的话，该怎么解决呢？