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USB: open disconnect race in usblcd

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

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Oliver Neukum 2007-10-25 16:05:53 +02:00 committed by Greg Kroah-Hartman
parent 78663ecc34
commit d5d1ceac2a
1 changed files with 10 additions and 1 deletions
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11
drivers/usb/misc/usblcd.c
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@ -17,6 +17,7 @@
#include <linux/init.h> #include <linux/init.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/errno.h> #include <linux/errno.h>
#include <linux/mutex.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
#include <linux/usb.h> #include <linux/usb.h>
@ -34,6 +35,8 @@ static struct usb_device_id id_table [] = {
}; };
MODULE_DEVICE_TABLE (usb, id_table); MODULE_DEVICE_TABLE (usb, id_table);
static DEFINE_MUTEX(open_disc_mutex);
struct usb_lcd { struct usb_lcd {
struct usb_device * udev; /* init: probe_lcd */ struct usb_device * udev; /* init: probe_lcd */
@ -79,12 +82,16 @@ static int lcd_open(struct inode *inode, struct file *file)
return -ENODEV; return -ENODEV;
} }
mutex_lock(&open_disc_mutex);
dev = usb_get_intfdata(interface); dev = usb_get_intfdata(interface);
if (!dev) if (!dev) {
mutex_unlock(&open_disc_mutex);
return -ENODEV; return -ENODEV;
}
/* increment our usage count for the device */ /* increment our usage count for the device */
kref_get(&dev->kref); kref_get(&dev->kref);
mutex_unlock(&open_disc_mutex);
/* grab a power reference */ /* grab a power reference */
r = usb_autopm_get_interface(interface); r = usb_autopm_get_interface(interface);
@ -393,8 +400,10 @@ static void lcd_disconnect(struct usb_interface *interface)
struct usb_lcd *dev; struct usb_lcd *dev;
int minor = interface->minor; int minor = interface->minor;
mutex_lock(&open_disc_mutex);
dev = usb_get_intfdata(interface); dev = usb_get_intfdata(interface);
usb_set_intfdata(interface, NULL); usb_set_intfdata(interface, NULL);
mutex_unlock(&open_disc_mutex);
/* give back our minor */ /* give back our minor */
usb_deregister_dev(interface, &lcd_class); usb_deregister_dev(interface, &lcd_class);