3.16.80-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Johan Hovold johan@kernel.org
commit cd81e6fa8e033e7bcd59415b4a65672b4780030b upstream.
The driver is using its struct usb_device pointer as an inverted disconnected flag, but was setting it to NULL before making sure all completion handlers had run. This could lead to a NULL-pointer dereference in a number of dev_dbg and dev_err statements in the completion handlers which relies on said pointer.
Fix this by unconditionally stopping all I/O and preventing resubmissions by poisoning the interrupt URBs at disconnect and using a dedicated disconnected flag.
This also makes sure that all I/O has completed by the time the disconnect callback returns.
Fixes: 9d974b2a06e3 ("USB: legousbtower.c: remove err() usage") Fixes: fef526cae700 ("USB: legousbtower: remove custom debug macro") Fixes: 4dae99638097 ("USB: legotower: remove custom debug macro and module parameter") Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20190919083039.30898-4-johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/misc/legousbtower.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-)
--- a/drivers/usb/misc/legousbtower.c +++ b/drivers/usb/misc/legousbtower.c @@ -196,6 +196,7 @@ struct lego_usb_tower { unsigned char minor; /* the starting minor number for this device */
int open_count; /* number of times this port has been opened */ + unsigned long disconnected:1;
char* read_buffer; size_t read_buffer_length; /* this much came in */ @@ -295,8 +296,6 @@ static inline void lego_usb_tower_debug_ */ static inline void tower_delete (struct lego_usb_tower *dev) { - tower_abort_transfers (dev); - /* free data structures */ usb_free_urb(dev->interrupt_in_urb); usb_free_urb(dev->interrupt_out_urb); @@ -436,7 +435,8 @@ static int tower_release (struct inode * retval = -ENODEV; goto unlock_exit; } - if (dev->udev == NULL) { + + if (dev->disconnected) { /* the device was unplugged before the file was released */
/* unlock here as tower_delete frees dev */ @@ -472,10 +472,9 @@ static void tower_abort_transfers (struc if (dev->interrupt_in_running) { dev->interrupt_in_running = 0; mb(); - if (dev->udev) - usb_kill_urb (dev->interrupt_in_urb); + usb_kill_urb(dev->interrupt_in_urb); } - if (dev->interrupt_out_busy && dev->udev) + if (dev->interrupt_out_busy) usb_kill_urb(dev->interrupt_out_urb); }
@@ -511,7 +510,7 @@ static unsigned int tower_poll (struct f
dev = file->private_data;
- if (!dev->udev) + if (dev->disconnected) return POLLERR | POLLHUP;
poll_wait(file, &dev->read_wait, wait); @@ -558,7 +557,7 @@ static ssize_t tower_read (struct file * }
/* verify that the device wasn't unplugged */ - if (dev->udev == NULL) { + if (dev->disconnected) { retval = -ENODEV; pr_err("No device or device unplugged %d\n", retval); goto unlock_exit; @@ -644,7 +643,7 @@ static ssize_t tower_write (struct file }
/* verify that the device wasn't unplugged */ - if (dev->udev == NULL) { + if (dev->disconnected) { retval = -ENODEV; pr_err("No device or device unplugged %d\n", retval); goto unlock_exit; @@ -753,7 +752,7 @@ static void tower_interrupt_in_callback
resubmit: /* resubmit if we're still running */ - if (dev->interrupt_in_running && dev->udev) { + if (dev->interrupt_in_running) { retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC); if (retval) dev_err(&dev->udev->dev, @@ -823,6 +822,7 @@ static int tower_probe (struct usb_inter
dev->udev = udev; dev->open_count = 0; + dev->disconnected = 0;
dev->read_buffer = NULL; dev->read_buffer_length = 0; @@ -970,6 +970,10 @@ static void tower_disconnect (struct usb /* give back our minor and prevent further open() */ usb_deregister_dev (interface, &tower_class);
+ /* stop I/O */ + usb_poison_urb(dev->interrupt_in_urb); + usb_poison_urb(dev->interrupt_out_urb); + mutex_lock(&dev->lock);
/* if the device is not opened, then we clean up right now */ @@ -977,7 +981,7 @@ static void tower_disconnect (struct usb mutex_unlock(&dev->lock); tower_delete (dev); } else { - dev->udev = NULL; + dev->disconnected = 1; /* wake up pollers */ wake_up_interruptible_all(&dev->read_wait); wake_up_interruptible_all(&dev->write_wait);