Messages in this thread | | | Date | Thu, 08 Aug 2019 07:33:25 -0700 | Subject | Re: Re: possible deadlock in open_rio | From | syzbot <> |
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> 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[] = {
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