2013-03-01 21:39:58

by Alexey Khoroshilov

Subject: [PATCH] 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 <[email protected]>
---
drivers/block/drbd/drbd_proc.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/block/drbd/drbd_proc.c b/drivers/block/drbd/drbd_proc.c
index 56672a6..30fe0a5 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;
}

--
1.7.9.5

2013-03-04 20:31:18

by Philipp Reisner

Subject: Re: [PATCH] drbd: add module_put() on error path in drbd_proc_open()

Hi Alexey,

Thanks a lot! I have put it into our tree.
http://git.drbd.org/gitweb.cgi?p=drbd-8.4.git

I intend to get it into the 3.10 merge window.

Best,
Phil

> 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 <[email protected]>
> ---
> drivers/block/drbd/drbd_proc.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/drbd/drbd_proc.c b/drivers/block/drbd/drbd_proc.c
> index 56672a6..30fe0a5 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;
> }