* glibc detected * realloc(): invalid next size:

Question

I have a problem with realloc function:

*** glibc detected *** realloc(): invalid next size:

Here is the relevant part of code:

    char* pathfile = NULL;
    int tcpargc=6;
    char *tcpargv[tcpargc];
    int it;
    for (it = 0;it < tcpargc;it++)
       tcpargv[it] = NULL;
    ...
    while (1) {
    ...
    if (pathfile == NULL)
       pathfile=(char*)malloc((strlen(RAMDIR)+strlen(tempfilename)+7)*sizeof(char));
    else {
    if ((tmp=(char*)realloc(pathfile,(strlen(RAMDIR)+strlen(tempfilename)+7)*sizeof(char))) == NULL)
    {
 printf("ERROR: realloc failed");
        free(pathfile);
    }
    else
        pathfile = tmp;
    }
    ...
    if (tcpargv[4] == NULL)
    tcpargv[4]=(char*)malloc((strlen("--infile=")+strlen(pathfile)+1)*sizeof(char));
    else {
    if ((tmp = (char*)realloc(tcpargv[4],strlen("--infile=")+strlen(pathfile)+1)*sizeof(char)))   == NULL){
    printf("ERROR: realloc failed");
    free(tcpargv[4]);
    }
    else
    tcpargv[4] = tmp;
    } 
    ...    
    }

I have checked it again and again but I could not find the error.
Thanks for you help.

Answer 1

That error indicates that your code is probably overwriting bookkeeping data used by the glibc memory allocation subsystem. As Michael Mior suggested in his comment, try running your code under Valgrind -- it's quite good at finding such memory corruption errors.