Description of problem:
functions selabel_lookup and selabel_lookup_raw 

Version-Release number of selected component (if applicable):
libselinux-2.0.94-7.el6.x86_64

Steps to Reproduce:
1. Run this program:
#include <stdio.h>
#include <selinux/selinux.h>
#include <selinux/label.h>

int main (int argc, char **argv) {
    struct selabel_handle *hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);

    security_context_t selabel_context;

    // path == NULL
    selabel_lookup(hnd, &selabel_context, NULL, 0);

    freecon(selabel_context);
    selabel_close(hnd);
}

Actual results:
Segmentation fault

Expected results:
errno == EINVAL

Additional info:
This bug is fixed in 7.3, upstream fix is here: https://github.com/SELinuxProject/selinux/commit/16a37c9f94c1e2dfb865e17e4200d2824d4971f5