From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jerome Marchand , Rashika Kheria , Minchan Kim Subject: [PATCH 3.12 025/116] Staging: zram: Fix access of NULL pointer Date: Tue, 26 Nov 2013 16:56:38 -0800 Message-Id: <20131127005738.685642840@linuxfoundation.org> In-Reply-To: <20131127005736.915454872@linuxfoundation.org> References: <20131127005736.915454872@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.12-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 --- drivers/staging/zram/zram_drv.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/staging/zram/zram_drv.c +++ b/drivers/staging/zram/zram_drv.c @@ -648,6 +648,9 @@ 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; @@ -660,8 +663,7 @@ 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); zram_reset_device(zram, true); return len;