This is a note to let you know that I've just added the patch titled
zram: restrict add/remove attributes to root only
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
zram-restrict-add-remove-attributes-to-root-only.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5c7e9ccd91b90d87029261f8856294ee51934cab Mon Sep 17 00:00:00 2001
From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Date: Wed, 7 Dec 2016 14:44:31 -0800
Subject: zram: restrict add/remove attributes to root only
From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
commit 5c7e9ccd91b90d87029261f8856294ee51934cab upstream.
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.
[akpm@xxxxxxxxxxxxxxxxxxxx: s/sence/sense/, reflow comment to use 80 cols]
Fixes: 6566d1a32bf72 ("zram: add dynamic device add/remove functionality")
Link: http://lkml.kernel.org/r/20161205155845.20129-1-sergey.senozhatsky@xxxxxxxxx
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Reported-by: Steven Allen <steven@xxxxxxxxxxxxx>
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1378,8 +1378,14 @@ static ssize_t hot_remove_store(struct c
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),
__ATTR_WO(hot_remove),
__ATTR_NULL,
};
Patches currently in stable-queue which might be from sergey.senozhatsky@xxxxxxxxx are
queue-4.4/zram-restrict-add-remove-attributes-to-root-only.patch
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