Commit 5863e10b authored Jun 07, 2013 by Jiang Liu Committed by Greg Kroah-Hartman Jun 06, 2013

zram: protect sysfs handler from invalid memory access



Use zram->init_lock to protect access to zram->meta, otherwise it
may cause invalid memory access if zram->meta has been freed by
zram_reset_device().

This issue may be triggered by:
Thread 1:
while true; do cat mem_used_total; done
Thread 2:
while true; do echo 8M > disksize; echo 1 > reset; done

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 12a7ad3b

drivers/staging/zram/zram_sysfs.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -188,8 +188,10 @@ static ssize_t mem_used_total_show(struct device *dev,
		struct zram *zram = dev_to_zram(dev);
		struct zram_meta *meta = zram->meta;

		down_read(&zram->init_lock);
		if (zram->init_done)
		val = zs_get_total_size_bytes(meta->mem_pool);
		up_read(&zram->init_lock);

		return sprintf(buf, "%llu\n", val);
		}