selinuxfs snprintf() misuses

a) %d does _not_ produce a page worth of output
b) snprintf() doesn't return negatives - it used to in old glibc, but
that's the kernel...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

security/selinux/selinuxfs.c

@@ -1259,12 +1259,8 @@ static int sel_make_bools(void)
 		if (!inode)
 			goto out;
 
-		ret = -EINVAL;
-		len = snprintf(page, PAGE_SIZE, "/%s/%s", BOOL_DIR_NAME, names[i]);
-		if (len < 0)
-			goto out;
-
 		ret = -ENAMETOOLONG;
+		len = snprintf(page, PAGE_SIZE, "/%s/%s", BOOL_DIR_NAME, names[i]);
 		if (len >= PAGE_SIZE)
 			goto out;
 
@@ -1557,19 +1553,10 @@ static inline u32 sel_ino_to_perm(unsigned long ino)
 static ssize_t sel_read_class(struct file *file, char __user *buf,
 				size_t count, loff_t *ppos)
 {
-	ssize_t rc, len;
-	char *page;
 	unsigned long ino = file->f_path.dentry->d_inode->i_ino;
-
-	page = (char *)__get_free_page(GFP_KERNEL);
-	if (!page)
-		return -ENOMEM;
-
-	len = snprintf(page, PAGE_SIZE, "%d", sel_ino_to_class(ino));
-	rc = simple_read_from_buffer(buf, count, ppos, page, len);
-	free_page((unsigned long)page);
-
-	return rc;
+	char res[TMPBUFLEN];
+	ssize_t len = snprintf(res, sizeof(res), "%d", sel_ino_to_class(ino));
+	return simple_read_from_buffer(buf, count, ppos, res, len);
 }
 
 static const struct file_operations sel_class_ops = {
@@ -1580,19 +1567,10 @@ static const struct file_operations sel_class_ops = {
 static ssize_t sel_read_perm(struct file *file, char __user *buf,
 				size_t count, loff_t *ppos)
 {
-	ssize_t rc, len;
-	char *page;
 	unsigned long ino = file->f_path.dentry->d_inode->i_ino;
-
-	page = (char *)__get_free_page(GFP_KERNEL);
-	if (!page)
-		return -ENOMEM;
-
-	len = snprintf(page, PAGE_SIZE, "%d", sel_ino_to_perm(ino));
-	rc = simple_read_from_buffer(buf, count, ppos, page, len);
-	free_page((unsigned long)page);
-
-	return rc;
+	char res[TMPBUFLEN];
+	ssize_t len = snprintf(res, sizeof(res), "%d", sel_ino_to_perm(ino));
+	return simple_read_from_buffer(buf, count, ppos, res, len);
 }
 
 static const struct file_operations sel_perm_ops = {