[PATCH 3.5 19/96] Staging: zram: Fix memory leak by refcount mismatch

[Luis Henriques]

3.5.7.29 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rashika Kheria <rashika.kheria at gmail.com>

commit 1b672224d128ec2570eb37572ff803cfe452b4f7 upstream.

As suggested by Minchan Kim and Jerome Marchand "The code in reset_store
get the block device (bdget_disk()) but it does not put it (bdput()) when
it's done using it. The usage count is therefore incremented but never
decremented."

This patch also puts bdput() for all error cases.

Acked-by: Minchan Kim <minchan at kernel.org>
Acked-by: Jerome Marchand <jmarchan at redhat.com>
Signed-off-by: Rashika Kheria <rashika.kheria at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ luis: backported to 3.5:
  - adjusted filename: zram_drv.c -> zram_sysfs.c
  - adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/staging/zram/zram_sysfs.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c
index 01f9a79..aafcf03 100644
--- a/drivers/staging/zram/zram_sysfs.c
+++ b/drivers/staging/zram/zram_sysfs.c
@@ -99,18 +99,23 @@ static ssize_t reset_store(struct device *dev,
 		return -ENOMEM;
 
 	/* Do not reset an active device! */
-	if (bdev->bd_holders)
-		return -EBUSY;
+	if (bdev->bd_holders) {
+		ret = -EBUSY;
+		goto out;
+	}
 
 	ret = kstrtou16(buf, 10, &do_reset);
 	if (ret)
-		return ret;
+		goto out;
 
-	if (!do_reset)
-		return -EINVAL;
+	if (!do_reset) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	/* Make sure all pending I/O is finished */
 	fsync_bdev(bdev);
+	bdput(bdev);
 
 	down_write(&zram->init_lock);
 	if (zram->init_done)
@@ -118,6 +123,10 @@ static ssize_t reset_store(struct device *dev,
 	up_write(&zram->init_lock);
 
 	return len;
+
+out:
+	bdput(bdev);
+	return ret;
 }
 
 static ssize_t num_reads_show(struct device *dev,
-- 
1.8.3.2