there are several potential NULL pointer dereference vulnerabilities

[xambroz]

Hello,
there are several places in the code where it could potentially happen that the NULL pointer result from previous tests is attempted to be derefenced.

Code like this:

       s->data = malloc(i + 1);
       memset(s->data, 0, i + 1);

Should become like this:

       s->data = malloc(i + 1);
       if (NULL == s->data)
       {
               return -1;
       }
       memset(s->data, 0, i + 1);

Please consider to accept the pull request:
#19

Best regards
Michal Ambroz