Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752550AbdFAQBa (ORCPT ); Thu, 1 Jun 2017 12:01:30 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33881 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752272AbdFAPpO (ORCPT ); Thu, 1 Jun 2017 11:45:14 -0400 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, "Mauro Carvalho Chehab" , "Arnd Bergmann" Date: Thu, 01 Jun 2017 16:43:16 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 196/212] [media] dvb-usb-v2: avoid use-after-free In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 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 Content-Length: 2267 Lines: 57 3.16.44-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Arnd Bergmann commit 005145378c9ad7575a01b6ce1ba118fb427f583a upstream. I ran into a stack frame size warning because of the on-stack copy of the USB device structure: drivers/media/usb/dvb-usb-v2/dvb_usb_core.c: In function 'dvb_usbv2_disconnect': drivers/media/usb/dvb-usb-v2/dvb_usb_core.c:1029:1: error: the frame size of 1104 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] Copying a device structure like this is wrong for a number of other reasons too aside from the possible stack overflow. One of them is that the dev_info() call will print the name of the device later, but AFAICT we have only copied a pointer to the name earlier and the actual name has been freed by the time it gets printed. This removes the on-stack copy of the device and instead copies the device name using kstrdup(). I'm ignoring the possible failure here as both printk() and kfree() are able to deal with NULL pointers. Signed-off-by: Arnd Bergmann Signed-off-by: Mauro Carvalho Chehab [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- drivers/media/usb/dvb-usb-v2/dvb_usb_core.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c +++ b/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c @@ -942,8 +942,8 @@ EXPORT_SYMBOL(dvb_usbv2_probe); void dvb_usbv2_disconnect(struct usb_interface *intf) { struct dvb_usb_device *d = usb_get_intfdata(intf); - const char *name = d->name; - struct device dev = d->udev->dev; + const char *devname = kstrdup(dev_name(&d->udev->dev), GFP_KERNEL); + const char *drvname = d->name; dev_dbg(&d->udev->dev, "%s: bInterfaceNumber=%d\n", __func__, intf->cur_altsetting->desc.bInterfaceNumber); @@ -952,8 +952,9 @@ void dvb_usbv2_disconnect(struct usb_int dvb_usbv2_exit(d); - dev_info(&dev, "%s: '%s' successfully deinitialized and disconnected\n", - KBUILD_MODNAME, name); + pr_info("%s: '%s:%s' successfully deinitialized and disconnected\n", + KBUILD_MODNAME, drvname, devname); + kfree(devname); } EXPORT_SYMBOL(dvb_usbv2_disconnect);