| From f24ac9069df87fde1de5c50a7ec994e17baf0fc8 Mon Sep 17 00:00:00 2001 |
| From: Johan Hovold <johan@kernel.org> |
| Date: Wed, 9 Oct 2019 12:48:41 +0200 |
| Subject: [PATCH] USB: iowarrior: fix use-after-free on disconnect |
| |
| commit edc4746f253d907d048de680a621e121517f484b upstream. |
| |
| A recent fix addressing a deadlock on disconnect introduced a new bug |
| by moving the present flag out of the critical section protected by the |
| driver-data mutex. This could lead to a racing release() freeing the |
| driver data before disconnect() is done with it. |
| |
| Due to insufficient locking a related use-after-free could be triggered |
| also before the above mentioned commit. Specifically, the driver needs |
| to hold the driver-data mutex also while checking the opened flag at |
| disconnect(). |
| |
| Fixes: c468a8aa790e ("usb: iowarrior: fix deadlock on disconnect") |
| Fixes: 946b960d13c1 ("USB: add driver for iowarrior devices.") |
| Cc: stable <stable@vger.kernel.org> # 2.6.21 |
| Reported-by: syzbot+0761012cebf7bdb38137@syzkaller.appspotmail.com |
| Signed-off-by: Johan Hovold <johan@kernel.org> |
| Link: https://lore.kernel.org/r/20191009104846.5925-2-johan@kernel.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c |
| index f5bed9f29e56..4fe1d3267b3c 100644 |
| --- a/drivers/usb/misc/iowarrior.c |
| +++ b/drivers/usb/misc/iowarrior.c |
| @@ -866,8 +866,6 @@ static void iowarrior_disconnect(struct usb_interface *interface) |
| dev = usb_get_intfdata(interface); |
| mutex_lock(&iowarrior_open_disc_lock); |
| usb_set_intfdata(interface, NULL); |
| - /* prevent device read, write and ioctl */ |
| - dev->present = 0; |
| |
| minor = dev->minor; |
| mutex_unlock(&iowarrior_open_disc_lock); |
| @@ -878,8 +876,7 @@ static void iowarrior_disconnect(struct usb_interface *interface) |
| mutex_lock(&dev->mutex); |
| |
| /* prevent device read, write and ioctl */ |
| - |
| - mutex_unlock(&dev->mutex); |
| + dev->present = 0; |
| |
| if (dev->opened) { |
| /* There is a process that holds a filedescriptor to the device , |
| @@ -889,8 +886,10 @@ static void iowarrior_disconnect(struct usb_interface *interface) |
| usb_kill_urb(dev->int_in_urb); |
| wake_up_interruptible(&dev->read_wait); |
| wake_up_interruptible(&dev->write_wait); |
| + mutex_unlock(&dev->mutex); |
| } else { |
| /* no process is using the device, cleanup now */ |
| + mutex_unlock(&dev->mutex); |
| iowarrior_delete(dev); |
| } |
| |
| -- |
| 2.7.4 |
| |
