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USB: gadgetfs: fix copy_to_user while holding spinlock 

The gadgetfs driver as a long-outstanding FIXME, regarding a call of
copy_to_user() made while holding a spinlock.  This patch fixes the
issue by dropping the spinlock and using the dev->udc_usage mechanism
introduced by another recent patch to guard against status changes
while the lock isn't held.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
CC: <stable@vger.kernel.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern 2017-09-21 16:12:01 -04:00 committed by Greg Kroah-Hartman
parent 786de92b3c
commit 6e76c01e71
1 changed files with 4 additions and 1 deletions
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5
drivers/usb/gadget/legacy/inode.c
View File

@ -983,11 +983,14 @@ ep0_read (struct file *fd, char __user *buf, size_t len, loff_t *ptr)
retval = -EIO;
else {
len = min (len, (size_t)dev->req->actual);
// FIXME don't call this with the spinlock held ...
++dev->udc_usage;
spin_unlock_irq(&dev->lock);
if (copy_to_user (buf, dev->req->buf, len))
retval = -EFAULT;
else
retval = len;
spin_lock_irq(&dev->lock);
--dev->udc_usage;
clean_req (dev->gadget->ep0, dev->req);
/* NOTE userspace can't yet choose to stall */
}