From d5d1ceac2a47645780bd07fd7a670b14c4d995db Mon Sep 17 00:00:00 2001 From: Oliver Neukum Date: Thu, 25 Oct 2007 16:05:53 +0200 Subject: [PATCH] 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: Oliver Neukum Signed-off-by: Greg Kroah-Hartman --- drivers/usb/misc/usblcd.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/usb/misc/usblcd.c b/drivers/usb/misc/usblcd.c index 719842032712..20777d01db62 100644 --- a/drivers/usb/misc/usblcd.c +++ b/drivers/usb/misc/usblcd.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -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); -- 2.20.1