user_setenv(argv)
    char **argv;
{
    char *arg = argv[0];
    char *eqp;
    struct userenv *uep, **insp;

    if ((eqp = strchr(arg, '=')) == NULL) {
	option_error("missing = in name=value: %s", arg);
	return 0;
    }
    if (eqp == arg) {
	option_error("missing variable name: %s", arg);
	return 0;
    }
    for (uep = userenv_list; uep != NULL; uep = uep->ue_next) {
	int nlen = strlen(uep->ue_name);
	if (nlen == (eqp - arg) &&
	    strncmp(arg, uep->ue_name, nlen) == 0)
	    break;
    }
    /* Ignore attempts by unprivileged users to override privileged sources */
    if (uep != NULL && !privileged_option && uep->ue_priv)
	return 1;
    /* The name never changes, so allocate it with the structure */
    if (uep == NULL) {
	uep = malloc(sizeof (*uep) + (eqp-arg));
	strncpy(uep->ue_name, arg, eqp-arg);
	uep->ue_name[eqp-arg] = '\0';
	uep->ue_next = NULL;
	insp = &userenv_list;
	while (*insp != NULL)
	    insp = &(*insp)->ue_next;
	*insp = uep;
    } else {
	struct userenv *uep2;
	for (uep2 = userenv_list; uep2 != NULL; uep2 = uep2->ue_next) {
	    if (uep2 != uep && !uep2->ue_isset)
		break;
	}
	if (uep2 == NULL && !uep->ue_isset)
	    find_option("unset")->flags |= OPT_NOPRINT;
	free(uep->ue_value);
    }
    uep->ue_isset = 1;
    uep->ue_priv = privileged_option;
    uep->ue_source = option_source;
    uep->ue_value = strdup(eqp + 1);
    curopt->flags &= ~OPT_NOPRINT;
    return 1;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.