Messages in this thread | | | Subject | Re: [PATCH v2] rapidio: fix possible UAF when kfifo_alloc() fails | From | wangweiyang <> | Date | Tue, 22 Nov 2022 11:45:48 +0800 |
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Hi Andrew,
on 2022/11/22 6:04, Andrew Morton wrote: > 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.
Yes, I ignored that the initialization is still going on.
> >> 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.
I prefer to put the list addition just prior to the
filp->private_data = priv;
to keep mport_cdev_release() in reverse order of init. If it's ok with you, I'll send a new patch later.
> . >
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