Commit 58ecf131 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

USB: ldusb: fix NULL-derefs on driver unbind 



The driver was using its struct usb_interface 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, dev_warn 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: 2824bd25 ("[PATCH] USB: add ldusb driver")
Cc: stable <stable@vger.kernel.org>     # 2.6.13
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191009153848.8664-4-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 726b55d0

drivers/usb/misc/ldusb.c

+12 −12
Original line number Diff line number Diff line
@@ -153,6 +153,7 @@ MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in 
struct ld_usb {

	struct mutex		mutex;		/* locks this structure */

	struct usb_interface	*intf;		/* save off the usb interface pointer */

	unsigned long		disconnected:1;



	int			open_count;	/* number of times this port has been opened */
@@ -192,11 +193,9 @@ static void ld_usb_abort_transfers(struct ld_usb *dev) 
	/* shutdown transfer */

	if (dev->interrupt_in_running) {

		dev->interrupt_in_running = 0;

		if (dev->intf)

		usb_kill_urb(dev->interrupt_in_urb);

	}

	if (dev->interrupt_out_busy)

		if (dev->intf)

		usb_kill_urb(dev->interrupt_out_urb);

}
@@ -205,8 +204,6 @@ static void ld_usb_abort_transfers(struct ld_usb *dev) 
 */

static void ld_usb_delete(struct ld_usb *dev)

{

	ld_usb_abort_transfers(dev);



	/* free data structures */

	usb_free_urb(dev->interrupt_in_urb);

	usb_free_urb(dev->interrupt_out_urb);
@@ -263,7 +260,7 @@ static void ld_usb_interrupt_in_callback(struct urb *urb) 


resubmit:

	/* resubmit if we're still running */

	if (dev->interrupt_in_running && !dev->buffer_overflow && dev->intf) {

	if (dev->interrupt_in_running && !dev->buffer_overflow) {

		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);

		if (retval) {

			dev_err(&dev->intf->dev,
@@ -392,7 +389,7 @@ static int ld_usb_release(struct inode *inode, struct file *file) 
		retval = -ENODEV;

		goto unlock_exit;

	}

	if (dev->intf == NULL) {

	if (dev->disconnected) {

		/* the device was unplugged before the file was released */

		mutex_unlock(&dev->mutex);

		/* unlock here as ld_usb_delete frees dev */
@@ -423,7 +420,7 @@ static __poll_t ld_usb_poll(struct file *file, poll_table *wait) 


	dev = file->private_data;



	if (!dev->intf)

	if (dev->disconnected)

		return EPOLLERR | EPOLLHUP;



	poll_wait(file, &dev->read_wait, wait);
@@ -462,7 +459,7 @@ static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count, 
	}



	/* verify that the device wasn't unplugged */

	if (dev->intf == NULL) {

	if (dev->disconnected) {

		retval = -ENODEV;

		printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval);

		goto unlock_exit;
@@ -542,7 +539,7 @@ static ssize_t ld_usb_write(struct file *file, const char __user *buffer, 
	}



	/* verify that the device wasn't unplugged */

	if (dev->intf == NULL) {

	if (dev->disconnected) {

		retval = -ENODEV;

		printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval);

		goto unlock_exit;
@@ -764,6 +761,9 @@ static void ld_usb_disconnect(struct usb_interface *intf) 
	/* give back our minor */

	usb_deregister_dev(intf, &ld_usb_class);



	usb_poison_urb(dev->interrupt_in_urb);

	usb_poison_urb(dev->interrupt_out_urb);



	mutex_lock(&dev->mutex);



	/* if the device is not opened, then we clean up right now */
@@ -771,7 +771,7 @@ static void ld_usb_disconnect(struct usb_interface *intf) 
		mutex_unlock(&dev->mutex);

		ld_usb_delete(dev);

	} else {

		dev->intf = NULL;

		dev->disconnected = 1;

		/* wake up pollers */

		wake_up_interruptible_all(&dev->read_wait);

		wake_up_interruptible_all(&dev->write_wait);

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