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USB: legousbtower: fix potential NULL-deref on disconnect

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The driver is using its struct usb_device pointer as an inverted
disconnected flag, but was setting it to NULL before making sure all
completion handlers had run. This could lead to a NULL-pointer
dereference in a number of dev_dbg and dev_err statements in the
completion handlers which relies on said pointer.

Fix this by unconditionally stopping all I/O and preventing
resubmissions by poisoning the interrupt URBs at disconnect and using a
dedicated disconnected flag.

This also makes sure that all I/O has completed by the time the
disconnect callback returns.

Fixes: 9d974b2a06 ("USB: legousbtower.c: remove err() usage")
Fixes: fef526cae7 ("USB: legousbtower: remove custom debug macro")
Fixes: 4dae996380 ("USB: legotower: remove custom debug macro and module parameter")
Cc: stable <stable@vger.kernel.org>     # 3.5
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20190919083039.30898-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2019-09-19 10:30:38 +02:00 committed by Greg Kroah-Hartman
parent 33a7813219
commit cd81e6fa8e
1 changed files with 15 additions and 11 deletions
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26
drivers/usb/misc/legousbtower.c
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@ -190,6 +190,7 @@ struct lego_usb_tower {
unsigned char minor; /* the starting minor number for this device */
int open_count; /* number of times this port has been opened */
unsigned long disconnected:1;
char* read_buffer;
size_t read_buffer_length; /* this much came in */
@ -289,8 +290,6 @@ static inline void lego_usb_tower_debug_data(struct device *dev,
*/
static inline void tower_delete (struct lego_usb_tower *dev)
{
tower_abort_transfers (dev);
/* free data structures */
usb_free_urb(dev->interrupt_in_urb);
usb_free_urb(dev->interrupt_out_urb);
@ -430,7 +429,8 @@ static int tower_release (struct inode *inode, struct file *file)
retval = -ENODEV;
goto unlock_exit;
}
if (dev->udev == NULL) {
if (dev->disconnected) {
/* the device was unplugged before the file was released */
/* unlock here as tower_delete frees dev */
@ -466,10 +466,9 @@ static void tower_abort_transfers (struct lego_usb_tower *dev)
if (dev->interrupt_in_running) {
dev->interrupt_in_running = 0;
mb();
if (dev->udev)
usb_kill_urb (dev->interrupt_in_urb);
usb_kill_urb(dev->interrupt_in_urb);
}
if (dev->interrupt_out_busy && dev->udev)
if (dev->interrupt_out_busy)
usb_kill_urb(dev->interrupt_out_urb);
}
@ -505,7 +504,7 @@ static __poll_t tower_poll (struct file *file, poll_table *wait)
dev = file->private_data;
if (!dev->udev)
if (dev->disconnected)
return EPOLLERR | EPOLLHUP;
poll_wait(file, &dev->read_wait, wait);
@ -552,7 +551,7 @@ static ssize_t tower_read (struct file *file, char __user *buffer, size_t count,
}
/* verify that the device wasn't unplugged */
if (dev->udev == NULL) {
if (dev->disconnected) {
retval = -ENODEV;
pr_err("No device or device unplugged %d\n", retval);
goto unlock_exit;
@ -638,7 +637,7 @@ static ssize_t tower_write (struct file *file, const char __user *buffer, size_t
}
/* verify that the device wasn't unplugged */
if (dev->udev == NULL) {
if (dev->disconnected) {
retval = -ENODEV;
pr_err("No device or device unplugged %d\n", retval);
goto unlock_exit;
@ -748,7 +747,7 @@ static void tower_interrupt_in_callback (struct urb *urb)
resubmit:
/* resubmit if we're still running */
if (dev->interrupt_in_running && dev->udev) {
if (dev->interrupt_in_running) {
retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC);
if (retval)
dev_err(&dev->udev->dev,
@ -813,6 +812,7 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
dev->udev = udev;
dev->open_count = 0;
dev->disconnected = 0;
dev->read_buffer = NULL;
dev->read_buffer_length = 0;
@ -938,6 +938,10 @@ static void tower_disconnect (struct usb_interface *interface)
/* give back our minor and prevent further open() */
usb_deregister_dev (interface, &tower_class);
/* stop I/O */
usb_poison_urb(dev->interrupt_in_urb);
usb_poison_urb(dev->interrupt_out_urb);
mutex_lock(&dev->lock);
/* if the device is not opened, then we clean up right now */
@ -945,7 +949,7 @@ static void tower_disconnect (struct usb_interface *interface)
mutex_unlock(&dev->lock);
tower_delete (dev);
} else {
dev->udev = NULL;
dev->disconnected = 1;
/* wake up pollers */
wake_up_interruptible_all(&dev->read_wait);
wake_up_interruptible_all(&dev->write_wait);