3.16.80-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Johan Hovold johan@kernel.org
commit 58ecf131e74620305175a7aa103f81350bb37570 upstream.
The driver was using its struct usb_interface 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, dev_warn 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: 2824bd250f0b ("[PATCH] USB: add ldusb driver") Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20191009153848.8664-4-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/ldusb.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-)
--- a/drivers/usb/misc/ldusb.c +++ b/drivers/usb/misc/ldusb.c @@ -168,6 +168,7 @@ MODULE_PARM_DESC(min_interrupt_out_inter struct ld_usb { struct mutex mutex; /* locks this structure */ struct usb_interface* intf; /* save off the usb interface pointer */ + unsigned long disconnected:1;
int open_count; /* number of times this port has been opened */
@@ -207,12 +208,10 @@ static void ld_usb_abort_transfers(struc /* shutdown transfer */ if (dev->interrupt_in_running) { dev->interrupt_in_running = 0; - if (dev->intf) - usb_kill_urb(dev->interrupt_in_urb); + usb_kill_urb(dev->interrupt_in_urb); } if (dev->interrupt_out_busy) - if (dev->intf) - usb_kill_urb(dev->interrupt_out_urb); + usb_kill_urb(dev->interrupt_out_urb); }
/** @@ -220,8 +219,6 @@ static void ld_usb_abort_transfers(struc */ static void ld_usb_delete(struct ld_usb *dev) { - ld_usb_abort_transfers(dev); - /* free data structures */ usb_free_urb(dev->interrupt_in_urb); usb_free_urb(dev->interrupt_out_urb); @@ -277,7 +274,7 @@ static void ld_usb_interrupt_in_callback
resubmit: /* resubmit if we're still running */ - if (dev->interrupt_in_running && !dev->buffer_overflow && dev->intf) { + if (dev->interrupt_in_running && !dev->buffer_overflow) { retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC); if (retval) { dev_err(&dev->intf->dev, @@ -406,7 +403,7 @@ static int ld_usb_release(struct inode * retval = -ENODEV; goto unlock_exit; } - if (dev->intf == NULL) { + if (dev->disconnected) { /* the device was unplugged before the file was released */ mutex_unlock(&dev->mutex); /* unlock here as ld_usb_delete frees dev */ @@ -437,7 +434,7 @@ static unsigned int ld_usb_poll(struct f
dev = file->private_data;
- if (!dev->intf) + if (dev->disconnected) return POLLERR | POLLHUP;
poll_wait(file, &dev->read_wait, wait); @@ -476,7 +473,7 @@ static ssize_t ld_usb_read(struct file * }
/* verify that the device wasn't unplugged */ - if (dev->intf == NULL) { + if (dev->disconnected) { retval = -ENODEV; printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval); goto unlock_exit; @@ -556,7 +553,7 @@ static ssize_t ld_usb_write(struct file }
/* verify that the device wasn't unplugged */ - if (dev->intf == NULL) { + if (dev->disconnected) { retval = -ENODEV; printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval); goto unlock_exit; @@ -792,6 +789,9 @@ static void ld_usb_disconnect(struct usb /* give back our minor */ usb_deregister_dev(intf, &ld_usb_class);
+ usb_poison_urb(dev->interrupt_in_urb); + usb_poison_urb(dev->interrupt_out_urb); + mutex_lock(&dev->mutex);
/* if the device is not opened, then we clean up right now */ @@ -799,7 +799,7 @@ static void ld_usb_disconnect(struct usb mutex_unlock(&dev->mutex); ld_usb_delete(dev); } else { - dev->intf = NULL; + dev->disconnected = 1; /* wake up pollers */ wake_up_interruptible_all(&dev->read_wait); wake_up_interruptible_all(&dev->write_wait);