From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:53100 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731493AbeKLGFb (ORCPT ); Mon, 12 Nov 2018 01:05:31 -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, "Felipe Balbi" , "Yoshihiro Shimoda" , "Greg Kroah-Hartman" Date: Sun, 11 Nov 2018 19:49:05 +0000 Message-ID: Subject: [PATCH 3.16 086/366] usb: gadget: function: printer: avoid wrong list handling in printer_write() In-Reply-To: Sender: stable-owner@vger.kernel.org List-ID: 3.16.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Yoshihiro Shimoda commit 4a014a7339f441b0851ce012f469c0fadac61c81 upstream. When printer_write() calls usb_ep_queue(), a udc driver (e.g. renesas_usbhs driver) may call usb_gadget_giveback_request() in the udc .queue ops immediately. Then, printer_write() calls list_add(&req->list, &dev->tx_reqs_active) wrongly. After that, if we do unbind the printer driver, WARN_ON() happens in printer_func_unbind() because the list entry is not removed. So, this patch moves list_add(&req->list, &dev->tx_reqs_active) calling before usb_ep_queue(). Signed-off-by: Yoshihiro Shimoda 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/printer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/usb/gadget/printer.c +++ b/drivers/usb/gadget/printer.c @@ -667,19 +667,19 @@ printer_write(struct file *fd, const cha return -EAGAIN; } + list_add(&req->list, &dev->tx_reqs_active); + /* here, we unlock, and only unlock, to avoid deadlock. */ spin_unlock(&dev->lock); value = usb_ep_queue(dev->in_ep, req, GFP_ATOMIC); spin_lock(&dev->lock); if (value) { + list_del(&req->list); list_add(&req->list, &dev->tx_reqs); spin_unlock_irqrestore(&dev->lock, flags); mutex_unlock(&dev->lock_printer_io); return -EAGAIN; } - - list_add(&req->list, &dev->tx_reqs_active); - } spin_unlock_irqrestore(&dev->lock, flags);