From 7f850036134c491361e5297dde8762ac79934a83 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 21 Sep 2017 16:12:01 -0400 Subject: [PATCH] USB: gadgetfs: fix copy_to_user while holding spinlock 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 Reported-by: Andrey Konovalov Acked-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/legacy/inode.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c index 6ee73af35119..f69dbd4bcd18 100644 --- a/drivers/usb/gadget/legacy/inode.c +++ b/drivers/usb/gadget/legacy/inode.c @@ -986,11 +986,14 @@ 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 */ } -- 2.17.1