From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2E59C48BDB for ; Sun, 7 Jul 2019 19:38:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B755C20659 for ; Sun, 7 Jul 2019 19:38:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727820AbfGGTis (ORCPT ); Sun, 7 Jul 2019 15:38:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:57200 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727541AbfGGTiH (ORCPT ); Sun, 7 Jul 2019 15:38:07 -0400 Received: from 94.197.121.43.threembb.co.uk ([94.197.121.43] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hkCz5-0006gb-2o; Sun, 07 Jul 2019 20:38:03 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hkCz3-0005aE-EH; Sun, 07 Jul 2019 20:38:01 +0100 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, Denis Kirjanov , "Chiranjeevi Rapolu" , "Laurent Pinchart" , "Sakari Ailus" , "Mauro Carvalho Chehab" Date: Sun, 07 Jul 2019 17:54:17 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 049/129] media: uvcvideo: Avoid NULL pointer dereference at the end of streaming In-Reply-To: X-SA-Exim-Connect-IP: 94.197.121.43 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.70-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Sakari Ailus commit 9dd0627d8d62a7ddb001a75f63942d92b5336561 upstream. The UVC video driver converts the timestamp from hardware specific unit to one known by the kernel at the time when the buffer is dequeued. This is fine in general, but the streamoff operation consists of the following steps (among other things): 1. uvc_video_clock_cleanup --- the hardware clock sample array is released and the pointer to the array is set to NULL, 2. buffers in active state are returned to the user and 3. buf_finish callback is called on buffers that are prepared. buf_finish includes calling uvc_video_clock_update that accesses the hardware clock sample array. The above is serialised by a queue specific mutex. Address the problem by skipping the clock conversion if the hardware clock sample array is already released. Fixes: 9c0863b1cc48 ("[media] vb2: call buf_finish from __queue_cancel") Reported-by: Chiranjeevi Rapolu Tested-by: Chiranjeevi Rapolu Signed-off-by: Sakari Ailus Signed-off-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Ben Hutchings --- drivers/media/usb/uvc/uvc_video.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -627,6 +627,14 @@ void uvc_video_clock_update(struct uvc_s u32 rem; u64 y; + /* + * We will get called from __vb2_queue_cancel() if there are buffers + * done but not dequeued by the user, but the sample array has already + * been released at that time. Just bail out in that case. + */ + if (!clock->samples) + return; + spin_lock_irqsave(&clock->lock, flags); if (clock->count < clock->size)