3.2.97-rc1 review patch. If anyone has any objections, please let me know.
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From: Alan Stern stern@rowland.harvard.edu
commit 6e76c01e71551cb221c1f3deacb9dcd9a7346784 upstream.
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 Acked-by: Felipe Balbi felipe.balbi@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/gadget/inode.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/usb/gadget/inode.c +++ b/drivers/usb/gadget/inode.c @@ -1054,11 +1054,14 @@ ep0_read (struct file *fd, char __user * 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 */ }