Commit 5863e10b authored by Jiang Liu's avatar Jiang Liu Committed by Greg Kroah-Hartman

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: default avatarJiang Liu <jiang.liu@huawei.com>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 12a7ad3b
......@@ -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);
}
......
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