From patchwork Tue Nov 13 14:06:46 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans Verkuil X-Patchwork-Id: 10680771 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E8A3C14E2 for ; Tue, 13 Nov 2018 14:06:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D50DC28A55 for ; Tue, 13 Nov 2018 14:06:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C90C32A9B5; Tue, 13 Nov 2018 14:06:53 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 447742A9A6 for ; Tue, 13 Nov 2018 14:06:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387791AbeKNAFK (ORCPT ); Tue, 13 Nov 2018 19:05:10 -0500 Received: from lb1-smtp-cloud9.xs4all.net ([194.109.24.22]:49960 "EHLO lb1-smtp-cloud9.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733096AbeKNAFJ (ORCPT ); Tue, 13 Nov 2018 19:05:09 -0500 Received: from [IPv6:2001:420:44c1:2579:cc8b:c08b:b11b:69b9] ([IPv6:2001:420:44c1:2579:cc8b:c08b:b11b:69b9]) by smtp-cloud9.xs4all.net with ESMTPA id MZL5gH2ipSskCMZL8gsfwC; Tue, 13 Nov 2018 15:06:50 +0100 To: Linux Media Mailing List From: Hans Verkuil Subject: [PATCH] vb2: vb2_mmap: move lock up Message-ID: <71cb9482-fa06-def3-115e-105a0e0f3aec@xs4all.nl> Date: Tue, 13 Nov 2018 15:06:46 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 Content-Language: en-US X-CMAE-Envelope: MS4wfOu77AwDFjqCN5zIrVPVfmu0EFqFarZn3ylqO9RZoX0iqRJIZnSCQKZ6/4ihxrGWKMLuGmVpdLgcMrz95Mk5DBwiMVg/jDa8verNmCORWRtuR4DafNDg PhHwpMNHBu23p6W58iJhX6QkRIXyaq/B+jMyqphjH8I28SU1ID29o/8DJrLTcjs4MRIkwmkErclZ7lbSfEWzXhzr2cGL7+NaDIxgqvnUQK92ljn9Si5CJV0G mAPOlEZvM4aweNX7l+d+2xfup+1DU610gO6v+eeuX3Os4PeecCy8iKr5rWLOQYtq Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If a filehandle is dup()ped, then it is possible to close it from one fd and call mmap from the other. This creates a race condition in vb2_mmap where it is using queue data that __vb2_queue_free (called from close()) is in the process of releasing. By moving up the mutex_lock(mmap_lock) in vb2_mmap this race is avoided since __vb2_queue_free is called with the same mutex locked. So vb2_mmap now reads consistent buffer data. Signed-off-by: Hans Verkuil Reported-by: syzbot+be93025dd45dccd8923c@syzkaller.appspotmail.com --- drivers/media/common/videobuf2/videobuf2-core.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c index c49c67473408..03954c13024c 100644 --- a/drivers/media/common/videobuf2/videobuf2-core.c +++ b/drivers/media/common/videobuf2/videobuf2-core.c @@ -2120,9 +2120,13 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) return -EINVAL; } } + + mutex_lock(&q->mmap_lock); + if (vb2_fileio_is_active(q)) { dprintk(1, "mmap: file io in progress\n"); - return -EBUSY; + ret = -EBUSY; + goto unlock; } /* @@ -2130,7 +2134,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) */ ret = __find_plane_by_offset(q, off, &buffer, &plane); if (ret) - return ret; + goto unlock; vb = q->bufs[buffer]; @@ -2146,8 +2150,9 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) return -EINVAL; } - mutex_lock(&q->mmap_lock); ret = call_memop(vb, mmap, vb->planes[plane].mem_priv, vma); + +unlock: mutex_unlock(&q->mmap_lock); if (ret) return ret;