[PATCH] usb: fix slab-use-after-free Read in hdm_disconnect

[Camila Alvarez]

All references on the device were lost when deregistering the interface.
To make sure the device is not released before freeing all the memory we
add get_device to increase the ref count by one.

Reported-by: syzbot+916742d5d24f6c254761@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=916742d5d24f6c254761
Signed-off-by: Camila Alvarez <cam.alvarez.i@xxxxxxxxx>
---
 drivers/most/most_usb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/most/most_usb.c b/drivers/most/most_usb.c
index 485d5ca39951..e178a5a0d3aa 100644
--- a/drivers/most/most_usb.c
+++ b/drivers/most/most_usb.c
@@ -1120,6 +1120,7 @@ static void hdm_disconnect(struct usb_interface *interface)
 
 	if (mdev->dci)
 		device_unregister(&mdev->dci->dev);
+	get_device(&mdev->dev);
 	most_deregister_interface(&mdev->iface);
 
 	kfree(mdev->busy_urbs);
-- 
2.34.1