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=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT 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 ABEFFC46460 for ; Thu, 30 May 2019 04:59:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8508B2606F for ; Thu, 30 May 2019 04:59:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559192369; bh=oQ2SeGOQu9iHPbVZedgYxDzhJB7H1HLmK4H2HDHddqc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2Yed3bBpZNWQxyvNyHOU66s2fgJQ5B4TiwuyvQa74LtDvCCtSGN0jzDG4UkfKjlll udi0tgHZ2VoNdaksf08TNm3ycBNX+eslEKVPlJ0ykPl6pL9VsC0htPVUYu77gccbSH qcmavd9cMe9t5gnkAiN65DuPACbIEScmrP6G1FME= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727687AbfE3DJj (ORCPT ); Wed, 29 May 2019 23:09:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:44512 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727679AbfE3DJi (ORCPT ); Wed, 29 May 2019 23:09:38 -0400 Received: from localhost (ip67-88-213-2.z213-88-67.customer.algx.net [67.88.213.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 523CB24492; Thu, 30 May 2019 03:09:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559185778; bh=oQ2SeGOQu9iHPbVZedgYxDzhJB7H1HLmK4H2HDHddqc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FEwrY/bi1voLcGLT9TClH7zreOkOQQiqSA3cjwfSnDK+mRhztREo4lAUbYR/uqlYO JD29lzxGEJNU15tbnrYO8OGynj8n9aRHag6lq6SvjIZhR0DlMB8XIBtcI2qEJ/aRlc lCOis7YssEOzoCT9DqqzmKxA9RektYaXT3ZUsRhY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hans Verkuil , Syzbot , Tomasz Figa , Hans Verkuil , Mauro Carvalho Chehab Subject: [PATCH 5.1 036/405] media: vb2: add waiting_in_dqbuf flag Date: Wed, 29 May 2019 20:00:34 -0700 Message-Id: <20190530030542.590936828@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190530030540.291644921@linuxfoundation.org> References: <20190530030540.291644921@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hans Verkuil commit d65842f7126aa1a87fb44b7c9980c12630ed4f33 upstream. Calling VIDIOC_DQBUF can release the core serialization lock pointed to by vb2_queue->lock if it has to wait for a new buffer to arrive. However, if userspace dup()ped the video device filehandle, then it is possible to read or call DQBUF from two filehandles at the same time. It is also possible to call REQBUFS from one filehandle while the other is waiting for a buffer. This will remove all the buffers and reallocate new ones. Removing all the buffers isn't the problem here (that's already handled correctly by DQBUF), but the reallocating part is: DQBUF isn't aware that the buffers have changed. This is fixed by setting a flag whenever the lock is released while waiting for a buffer to arrive. And checking the flag where needed so we can return -EBUSY. Signed-off-by: Hans Verkuil Reported-by: Syzbot Reviewed-by: Tomasz Figa Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Greg Kroah-Hartman --- drivers/media/common/videobuf2/videobuf2-core.c | 22 ++++++++++++++++++++++ include/media/videobuf2-core.h | 1 + 2 files changed, 23 insertions(+) --- a/drivers/media/common/videobuf2/videobuf2-core.c +++ b/drivers/media/common/videobuf2/videobuf2-core.c @@ -672,6 +672,11 @@ int vb2_core_reqbufs(struct vb2_queue *q return -EBUSY; } + if (q->waiting_in_dqbuf && *count) { + dprintk(1, "another dup()ped fd is waiting for a buffer\n"); + return -EBUSY; + } + if (*count == 0 || q->num_buffers != 0 || (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) { /* @@ -807,6 +812,10 @@ int vb2_core_create_bufs(struct vb2_queu } if (!q->num_buffers) { + if (q->waiting_in_dqbuf && *count) { + dprintk(1, "another dup()ped fd is waiting for a buffer\n"); + return -EBUSY; + } memset(q->alloc_devs, 0, sizeof(q->alloc_devs)); q->memory = memory; q->waiting_for_buffers = !q->is_output; @@ -1659,6 +1668,11 @@ static int __vb2_wait_for_done_vb(struct for (;;) { int ret; + if (q->waiting_in_dqbuf) { + dprintk(1, "another dup()ped fd is waiting for a buffer\n"); + return -EBUSY; + } + if (!q->streaming) { dprintk(1, "streaming off, will not wait for buffers\n"); return -EINVAL; @@ -1686,6 +1700,7 @@ static int __vb2_wait_for_done_vb(struct return -EAGAIN; } + q->waiting_in_dqbuf = 1; /* * We are streaming and blocking, wait for another buffer to * become ready or for streamoff. Driver's lock is released to @@ -1706,6 +1721,7 @@ static int __vb2_wait_for_done_vb(struct * the locks or return an error if one occurred. */ call_void_qop(q, wait_finish, q); + q->waiting_in_dqbuf = 0; if (ret) { dprintk(1, "sleep was interrupted\n"); return ret; @@ -2585,6 +2601,12 @@ static size_t __vb2_perform_fileio(struc if (!data) return -EINVAL; + if (q->waiting_in_dqbuf) { + dprintk(3, "another dup()ped fd is %s\n", + read ? "reading" : "writing"); + return -EBUSY; + } + /* * Initialize emulator on first call. */ --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -595,6 +595,7 @@ struct vb2_queue { unsigned int start_streaming_called:1; unsigned int error:1; unsigned int waiting_for_buffers:1; + unsigned int waiting_in_dqbuf:1; unsigned int is_multiplanar:1; unsigned int is_output:1; unsigned int copy_timestamp:1;