From: Sergey Senozhatsky Date: Wed, 7 Dec 2016 22:44:31 +0000 (-0800) Subject: zram: restrict add/remove attributes to root only X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5c7e9ccd91b90d87029261f8856294ee51934cab;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git 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. [akpm@linux-foundation.org: 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@gmail.com 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 --- 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), __ATTR_WO(hot_remove), __ATTR_NULL, };