From: Guanghui Feng guanghuifeng@linux.alibaba.com

stable inclusion from stable-v4.19.306 commit 3174e0f7de1ba392dc191625da83df02d695b60c category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I92HXN CVE: CVE-2023-52439

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit 0c9ae0b8605078eafc3bea053cc78791e97ba2e2 upstream.

core-1 core-2 ------------------------------------------------------- uio_unregister_device uio_open idev = idr_find() device_unregister(&idev->dev) put_device(&idev->dev) uio_device_release get_device(&idev->dev) kfree(idev) uio_free_minor(minor) uio_release put_device(&idev->dev) kfree(idev) -------------------------------------------------------

In the core-1 uio_unregister_device(), the device_unregister will kfree idev when the idev->dev kobject ref is 1. But after core-1 device_unregister, put_device and before doing kfree, the core-2 may get_device. Then: 1. After core-1 kfree idev, the core-2 will do use-after-free for idev. 2. When core-2 do uio_release and put_device, the idev will be double freed.

To address this issue, we can get idev atomic & inc idev reference with minor_lock.

Fixes: 57c5f4df0a5a ("uio: fix crash after the device is unregistered") Cc: stable stable@kernel.org Signed-off-by: Guanghui Feng guanghuifeng@linux.alibaba.com Reviewed-by: Baolin Wang baolin.wang@linux.alibaba.com Link: https://lore.kernel.org/r/1703152663-59949-1-git-send-email-guanghuifeng@lin... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

Signed-off-by: Guo Mengqi guomengqi3@huawei.com --- drivers/uio/uio.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index f43498e5cfb8..facccb36f692 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -464,13 +464,13 @@ static int uio_open(struct inode *inode, struct file *filep)

mutex_lock(&minor_lock); idev = idr_find(&uio_idr, iminor(inode)); - mutex_unlock(&minor_lock); if (!idev) { ret = -ENODEV; + mutex_unlock(&minor_lock); goto out; } - get_device(&idev->dev); + mutex_unlock(&minor_lock);

if (!try_module_get(idev->owner)) { ret = -ENODEV; @@ -1024,9 +1024,8 @@ void uio_unregister_device(struct uio_info *info) wake_up_interruptible(&idev->wait); kill_fasync(&idev->async_queue, SIGIO, POLL_HUP);

- device_unregister(&idev->dev); - uio_free_minor(minor); + device_unregister(&idev->dev);

return; }