Staging: zram: Fix memory leak by refcount mismatch

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@kernel.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 1b672224d128ec2570eb37572ff803cfe452b4f7)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 206f59d9a7a855fb3d68c22092fafba72cfe40fe..689ebf105acd6c98be136190b010f6782b7a2249 100644 (file)
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -652,21 +652,30 @@ 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);
 
        zram_reset_device(zram, true);
        return len;
+
+out:
+       bdput(bdev);
+       return ret;
 }
 
 static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)