Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

commit 853eab6 upstream.

Turns out that the permissions for 0400 really are what we want here,
otherwise any user can read from this file.

[fixed formatting, added changelog, and made attribute static - gregkh]

Reported-by: Wade Mealing <[email protected]>
Cc: stable <[email protected]>
Fixes: f40609d ("zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1847832
Reviewed-by: Steffen Maier <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Orabug: 31726827
CVE: CVE-2020-10781

(cherry picked from commit 5cd9ec70b9f6431fc3e60075c01bc00f08c5606b)
Signed-off-by: Vijayendra Suman <[email protected]>
Reviewed-by: John Donnelly <[email protected]>
Signed-off-by: Somasundaram Krishnasamy <[email protected]>

Author: wmealing

drivers/block/zram/zram_drv.c

@@ -1648,7 +1648,8 @@ static ssize_t hot_add_show(struct class *class,
 		return ret;
 	return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
 }
-static CLASS_ATTR_RO(hot_add);
+static struct class_attribute class_attr_hot_add =
+	__ATTR(hot_add, 0400, hot_add_show, NULL);
 
 static ssize_t hot_remove_store(struct class *class,
 			struct class_attribute *attr,