Messages in this thread | | | Date | Mon, 21 Nov 2022 14:04:10 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH v2] rapidio: fix possible UAF when kfifo_alloc() fails |
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On Sat, 19 Nov 2022 12:03:35 +0800 Wang Weiyang <wangweiyang2@huawei.com> wrote:
> If kfifo_alloc() fails in mport_cdev_open(), goto err_fifo and just free > priv. But priv is still in the chdev->file_list, then list traversal > may cause UAF. This fixes the following smatch warning: > > drivers/rapidio/devices/rio_mport_cdev.c:1930 mport_cdev_open() warn: '&priv->list' not removed from list > > ... > > Changes in v2: > - Avoid adding the new instance onto the list until the new instance > has been fully initialized.
But it still isn't fully initialized.
> drivers/rapidio/devices/rio_mport_cdev.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c > index 3cc83997a1f8..86b28c4cd906 100644 > --- a/drivers/rapidio/devices/rio_mport_cdev.c > +++ b/drivers/rapidio/devices/rio_mport_cdev.c > @@ -1904,10 +1904,6 @@ static int mport_cdev_open(struct inode *inode, struct file *filp) > > priv->md = chdev; > > - mutex_lock(&chdev->file_mutex); > - list_add_tail(&priv->list, &chdev->file_list); > - mutex_unlock(&chdev->file_mutex); > - > INIT_LIST_HEAD(&priv->db_filters); > INIT_LIST_HEAD(&priv->pw_filters); > spin_lock_init(&priv->fifo_lock); > @@ -1920,6 +1916,9 @@ static int mport_cdev_open(struct inode *inode, struct file *filp) > ret = -ENOMEM; > goto err_fifo; > } > + mutex_lock(&chdev->file_mutex); > + list_add_tail(&priv->list, &chdev->file_list); > + mutex_unlock(&chdev->file_mutex); > > #ifdef CONFIG_RAPIDIO_DMA_ENGINE > INIT_LIST_HEAD(&priv->async_list);
Here we're still setting up state at *priv. I'm thinking the list addition shouldn't occur until after the
filp->private_data = priv;
Or just prior to it. I'm not sure what the atomicity rules are for file.private versus mport_dev.file_list.
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