From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754625AbdL1Rjr (ORCPT ); Thu, 28 Dec 2017 12:39:47 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60253 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754390AbdL1Rei (ORCPT ); Thu, 28 Dec 2017 12:34:38 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Andrey Konovalov" , "Alan Stern" , "Felipe Balbi" Date: Thu, 28 Dec 2017 17:05:44 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 036/204] USB: gadgetfs: fix copy_to_user while holding spinlock In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.52-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern 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 [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings --- 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 @@ -1055,11 +1055,14 @@ 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 */ }