From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754323AbaFEEwT (ORCPT ); Thu, 5 Jun 2014 00:52:19 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44057 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752868AbaFEEVH (ORCPT ); Thu, 5 Jun 2014 00:21:07 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jerome Marchand , Rashika Kheria , Minchan Kim , Ben Hutchings , Jianguo Wu Subject: [PATCH 3.4 107/214] Staging: zram: Fix access of NULL pointer Date: Wed, 4 Jun 2014 21:17:50 -0700 Message-Id: <20140605041654.064572655@linuxfoundation.org> X-Mailer: git-send-email 2.0.0 In-Reply-To: <20140605041639.638675216@linuxfoundation.org> References: <20140605041639.638675216@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rashika Kheria commit 46a51c80216cb891f271ad021f59009f34677499 upstream. This patch fixes the bug in reset_store caused by accessing NULL pointer. The bdev gets its value from bdget_disk() which could fail when memory pressure is severe and hence can return NULL because allocation of inode in bdget could fail. Hence, this patch introduces a check for bdev to prevent reference to a NULL pointer in the later part of the code. It also removes unnecessary check of bdev for fsync_bdev(). Acked-by: Jerome Marchand Signed-off-by: Rashika Kheria Acked-by: Minchan Kim Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings Cc: Jianguo Wu Signed-off-by: Greg Kroah-Hartman --- drivers/staging/zram/zram_sysfs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/staging/zram/zram_sysfs.c +++ b/drivers/staging/zram/zram_sysfs.c @@ -95,6 +95,9 @@ static ssize_t reset_store(struct device zram = dev_to_zram(dev); bdev = bdget_disk(zram->disk, 0); + if (!bdev) + return -ENOMEM; + /* Do not reset an active device! */ if (bdev->bd_holders) return -EBUSY; @@ -107,8 +110,7 @@ static ssize_t reset_store(struct device return -EINVAL; /* Make sure all pending I/O is finished */ - if (bdev) - fsync_bdev(bdev); + fsync_bdev(bdev); down_write(&zram->init_lock); if (zram->init_done)