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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 A0A6AC43331 for ; Sun, 10 Nov 2019 06:42:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 753062085B for ; Sun, 10 Nov 2019 06:42:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573368169; bh=fW1d7tDJ8FH9jTgj3Wih7oMMQo7JBAvT71KAo3O07H8=; h=From:Date:Subject:To:Cc:Reply-to:List-ID:From; b=wYiAWbKN/o8OLlgLb0Zq1rWvXOHHpU7rzPZxBuGJdxo78NE7/YiBo6tB6qUOJ0oNY 5kDGM5AwdHW/SOdhlpFEX3Ko2byKUzJF6mITgYvYxgGsBX1hPmjH8qkcX4isC7+XEt xBpnB23pIkaQfIaMCjEVV2HFOkuu/PMY/RCLf5no= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725789AbfKJGms (ORCPT ); Sun, 10 Nov 2019 01:42:48 -0500 Received: from www.linuxtv.org ([130.149.80.248]:55979 "EHLO www.linuxtv.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725836AbfKJGms (ORCPT ); Sun, 10 Nov 2019 01:42:48 -0500 Received: from mchehab by www.linuxtv.org with local (Exim 4.84_2) (envelope-from ) id 1iTgvu-00053Q-IA; Sun, 10 Nov 2019 06:42:46 +0000 From: Mauro Carvalho Chehab Date: Fri, 08 Nov 2019 06:38:59 +0000 Subject: [git:media_tree/master] media: vivid: Fix wrong locking that causes race conditions on streaming stop To: linuxtv-commits@linuxtv.org Cc: Hans Verkuil , stable@vger.kernel.org, Linus Torvalds , Alexander Popov Mail-followup-to: linux-media@vger.kernel.org Forward-to: linux-media@vger.kernel.org Reply-to: linux-media@vger.kernel.org Message-Id: Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is an automatic generated email to let you know that the following patch were queued: Subject: media: vivid: Fix wrong locking that causes race conditions on streaming stop Author: Alexander Popov Date: Sun Nov 3 23:17:19 2019 +0100 There is the same incorrect approach to locking implemented in vivid_stop_generating_vid_cap(), vivid_stop_generating_vid_out() and sdr_cap_stop_streaming(). These functions are called during streaming stopping with vivid_dev.mutex locked. And they all do the same mistake while stopping their kthreads, which need to lock this mutex as well. See the example from vivid_stop_generating_vid_cap(): /* shutdown control thread */ vivid_grab_controls(dev, false); mutex_unlock(&dev->mutex); kthread_stop(dev->kthread_vid_cap); dev->kthread_vid_cap = NULL; mutex_lock(&dev->mutex); But when this mutex is unlocked, another vb2_fop_read() can lock it instead of vivid_thread_vid_cap() and manipulate the buffer queue. That causes a use-after-free access later. To fix those issues let's: 1. avoid unlocking the mutex in vivid_stop_generating_vid_cap(), vivid_stop_generating_vid_out() and sdr_cap_stop_streaming(); 2. use mutex_trylock() with schedule_timeout_uninterruptible() in the loops of the vivid kthread handlers. Signed-off-by: Alexander Popov Acked-by: Linus Torvalds Tested-by: Hans Verkuil Signed-off-by: Hans Verkuil Cc: # for v3.18 and up Signed-off-by: Mauro Carvalho Chehab drivers/media/platform/vivid/vivid-kthread-cap.c | 8 +++++--- drivers/media/platform/vivid/vivid-kthread-out.c | 8 +++++--- drivers/media/platform/vivid/vivid-sdr-cap.c | 8 +++++--- 3 files changed, 15 insertions(+), 9 deletions(-) --- diff --git a/drivers/media/platform/vivid/vivid-kthread-cap.c b/drivers/media/platform/vivid/vivid-kthread-cap.c index 9f981e8bae6e..01a9d671b947 100644 --- a/drivers/media/platform/vivid/vivid-kthread-cap.c +++ b/drivers/media/platform/vivid/vivid-kthread-cap.c @@ -818,7 +818,11 @@ static int vivid_thread_vid_cap(void *data) if (kthread_should_stop()) break; - mutex_lock(&dev->mutex); + if (!mutex_trylock(&dev->mutex)) { + schedule_timeout_uninterruptible(1); + continue; + } + cur_jiffies = jiffies; if (dev->cap_seq_resync) { dev->jiffies_vid_cap = cur_jiffies; @@ -998,8 +1002,6 @@ void vivid_stop_generating_vid_cap(struct vivid_dev *dev, bool *pstreaming) /* shutdown control thread */ vivid_grab_controls(dev, false); - mutex_unlock(&dev->mutex); kthread_stop(dev->kthread_vid_cap); dev->kthread_vid_cap = NULL; - mutex_lock(&dev->mutex); } diff --git a/drivers/media/platform/vivid/vivid-kthread-out.c b/drivers/media/platform/vivid/vivid-kthread-out.c index c974235d7de3..6780687978f9 100644 --- a/drivers/media/platform/vivid/vivid-kthread-out.c +++ b/drivers/media/platform/vivid/vivid-kthread-out.c @@ -166,7 +166,11 @@ static int vivid_thread_vid_out(void *data) if (kthread_should_stop()) break; - mutex_lock(&dev->mutex); + if (!mutex_trylock(&dev->mutex)) { + schedule_timeout_uninterruptible(1); + continue; + } + cur_jiffies = jiffies; if (dev->out_seq_resync) { dev->jiffies_vid_out = cur_jiffies; @@ -344,8 +348,6 @@ void vivid_stop_generating_vid_out(struct vivid_dev *dev, bool *pstreaming) /* shutdown control thread */ vivid_grab_controls(dev, false); - mutex_unlock(&dev->mutex); kthread_stop(dev->kthread_vid_out); dev->kthread_vid_out = NULL; - mutex_lock(&dev->mutex); } diff --git a/drivers/media/platform/vivid/vivid-sdr-cap.c b/drivers/media/platform/vivid/vivid-sdr-cap.c index 9acc709b0740..2b7522e16efc 100644 --- a/drivers/media/platform/vivid/vivid-sdr-cap.c +++ b/drivers/media/platform/vivid/vivid-sdr-cap.c @@ -141,7 +141,11 @@ static int vivid_thread_sdr_cap(void *data) if (kthread_should_stop()) break; - mutex_lock(&dev->mutex); + if (!mutex_trylock(&dev->mutex)) { + schedule_timeout_uninterruptible(1); + continue; + } + cur_jiffies = jiffies; if (dev->sdr_cap_seq_resync) { dev->jiffies_sdr_cap = cur_jiffies; @@ -303,10 +307,8 @@ static void sdr_cap_stop_streaming(struct vb2_queue *vq) } /* shutdown control thread */ - mutex_unlock(&dev->mutex); kthread_stop(dev->kthread_sdr_cap); dev->kthread_sdr_cap = NULL; - mutex_lock(&dev->mutex); } static void sdr_cap_buf_request_complete(struct vb2_buffer *vb)