This is a note to let you know that I've just added the patch titled USB: gadgetfs: fix copy_to_user while holding spinlock to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-gadgetfs-fix-copy_to_user-while-holding-spinlock.patch and it can be found in the queue-3.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 6e76c01e71551cb221c1f3deacb9dcd9a7346784 Mon Sep 17 00:00:00 2001 From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Date: Thu, 21 Sep 2017 16:12:01 -0400 Subject: USB: gadgetfs: fix copy_to_user while holding spinlock From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxx> Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Acked-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/gadget/legacy/inode.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/usb/gadget/legacy/inode.c +++ b/drivers/usb/gadget/legacy/inode.c @@ -1067,11 +1067,14 @@ 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 */ } Patches currently in stable-queue which might be from stern@xxxxxxxxxxxxxxxxxxx are queue-3.18/usb-dummy-hcd-fix-infinite-loop-resubmission-bug.patch queue-3.18/usb-storage-unusual_devs-entry-to-fix-write-access-regression-for-seagate-external-drives.patch queue-3.18/usb-gadgetfs-fix-copy_to_user-while-holding-spinlock.patch queue-3.18/usb-devio-don-t-corrupt-user-memory.patch queue-3.18/usb-gadgetfs-fix-crash-caused-by-inadequate-synchronization.patch queue-3.18/usb-dummy-hcd-fix-connection-failures-wrong-speed.patch