Properly check result of stat func in coroparse

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Fabio M. Di Nitto <fdinitto@redhat.com>

exec/coroparse.c

@@ -1158,8 +1158,8 @@ static int read_uidgid_files_into_icmap(
 		return_code = readdir_r(dp, entry, &dirent)) {
 
 		snprintf(filename, sizeof (filename), "%s/%s", dirname, dirent->d_name);
-		stat (filename, &stat_buf);
-		if (S_ISREG(stat_buf.st_mode)) {
+		res = stat (filename, &stat_buf);
+		if (res == 0 && S_ISREG(stat_buf.st_mode)) {
 
 			fp = fopen (filename, "r");
 			if (fp == NULL) continue;