From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756468Ab3FDQJB (ORCPT ); Tue, 4 Jun 2013 12:09:01 -0400 Received: from mail-pb0-f53.google.com ([209.85.160.53]:59930 "EHLO mail-pb0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756322Ab3FDQI6 (ORCPT ); Tue, 4 Jun 2013 12:08:58 -0400 From: Jiang Liu To: Greg Kroah-Hartman , Nitin Gupta , Minchan Kim , Jerome Marchand Cc: Yijing Wang , Jiang Liu , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 08/10] zram: protect sysfs handler from invalid memory access Date: Wed, 5 Jun 2013 00:06:06 +0800 Message-Id: <1370361968-8764-8-git-send-email-jiang.liu@huawei.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1370361968-8764-1-git-send-email-jiang.liu@huawei.com> References: <1370361968-8764-1-git-send-email-jiang.liu@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: stable@vger.kernel.org --- drivers/staging/zram/zram_sysfs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c index 8cb7822..e239d94 100644 --- a/drivers/staging/zram/zram_sysfs.c +++ b/drivers/staging/zram/zram_sysfs.c @@ -179,8 +179,10 @@ 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); } -- 1.8.1.2