PQconnectdbParams returns exit value 01 (from gdb).

I'm trying to create a connection to my database with libpq. Bellow is my
code:

PGconn *connect(char *file_path) {
const char **keywords;
const char **values;
char *line = malloc(LINE_SIZE);
char *prop, *val, *tmp;
int i = 0, j = 0, k = 0;
FILE *creds = fopen(file_path, "r");

if (creds == NULL) {
LOG("%s", "error: cannot open credentials file.\n");
exit(1);
}

keywords = malloc(6 * sizeof(char *));
values = malloc(6 * sizeof(char *));

while (fgets(line, LINE_SIZE, creds) != NULL) {
if (line[strlen(line) - 1] == '\n')
line[strlen(line) - 1] = '\0';
prop = line;
while(*(prop++) != '=') {
i++;
}
tmp = prop;
prop = malloc(i + 1);
strncpy(prop, line, i);
prop[i] = '\0';
keywords[j++] = prop;
val = malloc(strlen(line) - strlen(prop) + 1);
strcpy(val, tmp);
values[k++] = val;
i = 0;
}

keywords[++j] = NULL;
values[++k] = NULL;
printf("%s %s %s %s %s\n", keywords[0], keywords[1], keywords[2],
keywords[3], keywords[4]); //everything is printed well here
printf("%s %s %s %s %s\n", values[0], values[1], values[2], values[3],
values[4]); //here also

PGconn *conn = PQconnectdbParams(keywords, values, 1);

if (PQstatus(conn) != CONNECTION_OK) {
fprintf(stderr, "%s\n", PQerrorMessage(conn));
exit(1);
}

return conn;

}

If I run that code from main(), the printf works fine and nothing else is
printed after. But trying to use that connection, I realized that in fact
the PQconnectdbParams function returns value 01 (after debugging with gdb).

If I try to connect my database with the credentials from specified file,
it works well.

Can anybody help me on solving that issue?