双重免费或损坏错误

我一直收到这个错误:

*** glibc detected *** /s/httpget: double free or corruption (fasttop): 0x00000000005352a0 ***

我真的没有看到,我有两次免费.所以我猜它是因为腐败...我在附加的代码中做了一些评论,所以请看看那里,更好地理解问题.

Here backtrace:
#5  0x0000000000401077 in processXML (
    start=0x506010 "\n\n
\n
\n\n

这里的代码: 


void processXML(char *start, char *stop, GTree* t)
{
    if (start == NULL)return;
    start = strstr(start,START);
    char *  cp = start ;
    char * tmpP;
    gpointer* key;
    ticP tP;
    size_t  symlen=0;
    while (cp < stop)
    {
      //here the first occurance of the var, which causes the problem
      char * triP;
      cp  =  (strchr( cp, '"'))+1;
      tmpP = strchr( cp, '"');
      if ( tmpP != NULL )
      {
        symlen  = (tmpP - cp) ;
        printf("mallocated %zu\n", symlen) ;
        //EDIT
        triP = malloc(symlen+1);
        memcpy (triP, tmpP - (symlen) , symlen);
        triP [symlen]   = '\0';
        printf(">>VAL %s<<\n", triP);
        cp = strstr( cp, STARTP);
        if (cp == NULL){ return;}
      }
     if (triP != NULL && (key = g_tree_lookup (t, triP))== NULL )
     {
        printf("I N S E R T E D \n");
        tP = malloc(sizeof(tic));
        g_tree_insert(t, triP, tP);
     }
     //here I try to free it but only if some bytes were allocated...   
     if (symlen >0)free (triP);


怎么了？