drbd: add module_put() on error path in drbd_proc_open()

If single_open() fails in drbd_proc_open(), module refcount is left incremented.
The patch adds module_put() on the error path.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/block/drbd/drbd_proc.c b/drivers/block/drbd/drbd_proc.c
index 56672a61eb94..30fe0a57f5a0 100644
--- a/drivers/block/drbd/drbd_proc.c
+++ b/drivers/block/drbd/drbd_proc.c
@@ -313,8 +313,14 @@ static int drbd_seq_show(struct seq_file *seq, void *v)
 
 static int drbd_proc_open(struct inode *inode, struct file *file)
 {
-        if (try_module_get(THIS_MODULE))
-                return single_open(file, drbd_seq_show, PDE(inode)->data);
+        int err;
+
+        if (try_module_get(THIS_MODULE)) {
+                err = single_open(file, drbd_seq_show, PDE(inode)->data);
+                if (err)
+                        module_put(THIS_MODULE);
+                return err;
+        }
         return -ENODEV;
 }