On Wed, 7 Aug 2019, Oliver Neukum wrote:
Am Mittwoch, den 07.08.2019, 10:07 -0400 schrieb Alan Stern:
> On Wed, 7 Aug 2019, Oliver Neukum wrote:
> > technically yes. However in practical terms the straight revert I
sent
> > out yesterday should fix it.
>
> I didn't see the revert, and it doesn't appear to have reached the
> mailing list archive. Can you post it again?
As soon as our VPN server is back up again.
The revert may not be necessay; a little fix should get rid of the
locking violation. The key is to avoid calling the registration or
deregistration routines while holding the rio500_mutex, and to
recognize that the probe and disconnect routines are both protected by
the device mutex.
How does this patch look?
Alan Stern
#syz test: https://github.com/google/kasan.git 7f7867ff
This crash does not have a reproducer. I cannot test it.
Index: usb-devel/drivers/usb/misc/rio500.c
===================================================================
--- usb-devel.orig/drivers/usb/misc/rio500.c
+++ usb-devel/drivers/usb/misc/rio500.c
@@ -454,52 +454,54 @@ static int probe_rio(struct usb_interfac
{
struct usb_device *dev = interface_to_usbdev(intf);
struct rio_usb_data *rio = &rio_instance;
- int retval = 0;
+ int retval;
+ char *ibuf, *obuf;
- mutex_lock(&rio500_mutex);
if (rio->present) {
dev_info(&intf->dev, "Second USB Rio at address %d refused\n",
dev->devnum);
- retval = -EBUSY;
- goto bail_out;
- } else {
- dev_info(&intf->dev, "USB Rio found at address %d\n",
dev->devnum);
+ return -EBUSY;
}
+ dev_info(&intf->dev, "USB Rio found at address %d\n", dev->devnum);
retval = usb_register_dev(intf, &usb_rio_class);
if (retval) {
dev_err(&dev->dev,
"Not able to get a minor for this device.\n");
- retval = -ENOMEM;
- goto bail_out;
+ goto err_register;
}
- rio->rio_dev = dev;
-
- if (!(rio->obuf = kmalloc(OBUF_SIZE, GFP_KERNEL))) {
+ obuf = kmalloc(OBUF_SIZE, GFP_KERNEL);
+ if (!obuf) {
dev_err(&dev->dev,
"probe_rio: Not enough memory for the output buffer\n");
- usb_deregister_dev(intf, &usb_rio_class);
- retval = -ENOMEM;
- goto bail_out;
+ goto err_obuf;
}
- dev_dbg(&intf->dev, "obuf address:%p\n", rio->obuf);
+ dev_dbg(&intf->dev, "obuf address: %p\n", obuf);
- if (!(rio->ibuf = kmalloc(IBUF_SIZE, GFP_KERNEL))) {
+ ibuf = kmalloc(IBUF_SIZE, GFP_KERNEL);
+ if (!ibuf) {
dev_err(&dev->dev,
"probe_rio: Not enough memory for the input buffer\n");
- usb_deregister_dev(intf, &usb_rio_class);
- kfree(rio->obuf);
- retval = -ENOMEM;
- goto bail_out;
+ goto err_ibuf;
}
- dev_dbg(&intf->dev, "ibuf address:%p\n", rio->ibuf);
+ dev_dbg(&intf->dev, "ibuf address: %p\n", ibuf);
+ mutex_lock(&rio500_mutex);
+ rio->rio_dev = dev;
+ rio->ibuf = ibuf;
+ rio->obuf = obuf;
usb_set_intfdata (intf, rio);
rio->present = 1;
-bail_out:
mutex_unlock(&rio500_mutex);
return retval;
+
+ err_ibuf:
+ kfree(obuf);
+ err_obuf:
+ usb_deregister_dev(intf, &usb_rio_class);
+ err_register:
+ return -ENOMEM;
}
static void disconnect_rio(struct usb_interface *intf)
@@ -507,10 +509,10 @@ static void disconnect_rio(struct usb_in
struct rio_usb_data *rio = usb_get_intfdata (intf);
usb_set_intfdata (intf, NULL);
- mutex_lock(&rio500_mutex);
if (rio) {
usb_deregister_dev(intf, &usb_rio_class);
+ mutex_lock(&rio500_mutex);
if (rio->isopen) {
rio->isopen = 0;
/* better let it finish - the release will do whats
needed */
@@ -524,8 +526,8 @@ static void disconnect_rio(struct usb_in
dev_info(&intf->dev, "USB Rio disconnected.\n");
rio->present = 0;
+ mutex_unlock(&rio500_mutex);
}
- mutex_unlock(&rio500_mutex);
}
static const struct usb_device_id rio_table[] = {
