Messages in this thread | | | Date | Fri, 21 Aug 2020 11:14:49 +0300 | From | Dan Carpenter <> | Subject | Re: [PATCH] rapidio: fix get device imbalance on error |
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On Thu, Aug 20, 2020 at 10:44:57PM -0500, George Acosta wrote: > Fix the imbalance in mport_cdev_open. > Call put_device in error path to balance the > refcount that increased by the get_device. > > Fixes: e8de370188d0 ("rapidio: add mport char device driver") > Signed-off-by: George Acosta <acostag.ubuntu@gmail.com> > --- > drivers/rapidio/devices/rio_mport_cdev.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c > index c07ceec3c6d4..3b68e00eb40f 100644 > --- a/drivers/rapidio/devices/rio_mport_cdev.c > +++ b/drivers/rapidio/devices/rio_mport_cdev.c > @@ -1908,6 +1908,7 @@ static int mport_cdev_open(struct inode *inode, struct file *filp) > sizeof(struct rio_event) * MPORT_EVENT_DEPTH, > GFP_KERNEL); > if (ret < 0) { > + put_device(&chdev->dev); > dev_err(&chdev->dev, DRV_NAME ": kfifo_alloc failed\n"); > ret = -ENOMEM; > goto err_fifo; > --
If we ever hit this error path then the:
list_add_tail(&priv->list, &chdev->file_list);
needs to be removed from the list as well or it lead to a use after free. Probably just move the list_add_tail() after the kfifo_alloc() has succeeded. We need to remove it from the list in mport_cdev_release() as well...
The error handling in this function is kind of rubbish. 1) Get rid of the out label and return directly (more readable). 1b) Use "return 0;" instead of "retur ret;" for the success path. 2) Name the labels after what they do not where they "come from". In other words do.
err_priv: kfree(priv);
3) Create a label to call put_device:
err_device: put_device(&chdev->dev);
Change all the error paths to use the goto instead of calling put_device() before the goto.
regards, dan carpenter
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