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Commit d5d1ceac authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman
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USB: open disconnect race in usblcd 



this driver has a possible use after free due to a race when disconnect
and open handle intfdata without a lock.

Signed-off-by: default avatarOliver Neukum <oneukum@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 78663ecc

drivers/usb/misc/usblcd.c

+10 −1
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/init.h>

#include <linux/slab.h>

#include <linux/errno.h>

#include <linux/mutex.h>

#include <asm/uaccess.h>

#include <linux/usb.h>
@@ -34,6 +35,8 @@ static struct usb_device_id id_table [] = { 
};

MODULE_DEVICE_TABLE (usb, id_table);



static DEFINE_MUTEX(open_disc_mutex);





struct usb_lcd {

	struct usb_device *	udev;			/* init: probe_lcd */
@@ -79,12 +82,16 @@ static int lcd_open(struct inode *inode, struct file *file) 
		return -ENODEV;

	}



	mutex_lock(&open_disc_mutex);

	dev = usb_get_intfdata(interface);

	if (!dev)

	if (!dev) {

		mutex_unlock(&open_disc_mutex);

		return -ENODEV;

	}



	/* increment our usage count for the device */

	kref_get(&dev->kref);

	mutex_unlock(&open_disc_mutex);



	/* grab a power reference */

	r = usb_autopm_get_interface(interface);
@@ -393,8 +400,10 @@ static void lcd_disconnect(struct usb_interface *interface) 
	struct usb_lcd *dev;

        int minor = interface->minor;



	mutex_lock(&open_disc_mutex);

        dev = usb_get_intfdata(interface);

        usb_set_intfdata(interface, NULL);

	mutex_unlock(&open_disc_mutex);



        /* give back our minor */

        usb_deregister_dev(interface, &lcd_class);