diff options
authorSergey Senozhatsky <>2016-12-07 14:44:31 -0800
committerLinus Torvalds <>2016-12-07 17:10:00 -0800
commit5c7e9ccd91b90d87029261f8856294ee51934cab (patch)
parentea5a9eff96fed8252f3a8c94a84959f981a93cae (diff)
zram: restrict add/remove attributes to root only
zram hot_add sysfs attribute is a very 'special' attribute - reading from it creates a new uninitialized zram device. This file, by a mistake, can be read by a 'normal' user at the moment, while only root must be able to create a new zram device, therefore hot_add attribute must have S_IRUSR mode, not S_IRUGO. [ s/sence/sense/, reflow comment to use 80 cols] Fixes: 6566d1a32bf72 ("zram: add dynamic device add/remove functionality") Link: Signed-off-by: Sergey Senozhatsky <> Reported-by: Steven Allen <> Acked-by: Greg Kroah-Hartman <> Cc: Minchan Kim <> Cc: <> [4.2+] Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 5163c8f918cb..5497f7fc44d0 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1413,8 +1413,14 @@ static ssize_t hot_remove_store(struct class *class,
return ret ? ret : count;
+ * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
+ * sense that reading from this file does alter the state of your system -- it
+ * creates a new un-initialized zram device and returns back this device's
+ * device_id (or an error code if it fails to create a new device).
+ */
static struct class_attribute zram_control_class_attrs[] = {
- __ATTR_RO(hot_add),
+ __ATTR(hot_add, 0400, hot_add_show, NULL),