Commit 46a51c80 authored Oct 30, 2013 by Rashika Kheria Committed by Greg Kroah-Hartman Oct 30, 2013

Staging: zram: Fix access of NULL pointer



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().

Cc: stable <stable@vger.kernel.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 59d3fe54

drivers/staging/zram/zram_drv.c

+4 −2

Original line number	Original line	Diff line number	Diff line
	@@ -648,6 +648,9 @@ static ssize_t reset_store(struct device *dev,
	zram = dev_to_zram(dev);		zram = dev_to_zram(dev);
	bdev = bdget_disk(zram->disk, 0);		bdev = bdget_disk(zram->disk, 0);

			if (!bdev)
			return -ENOMEM;

	/* Do not reset an active device! */		/* Do not reset an active device! */
	if (bdev->bd_holders)		if (bdev->bd_holders)
	return -EBUSY;		return -EBUSY;
	@@ -660,7 +663,6 @@ static ssize_t reset_store(struct device *dev,
	return -EINVAL;		return -EINVAL;

	/* Make sure all pending I/O is finished */		/* Make sure all pending I/O is finished */
	if (bdev)
	fsync_bdev(bdev);		fsync_bdev(bdev);

	zram_reset_device(zram, true);		zram_reset_device(zram, true);