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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 2FAD9C433E2 for ; Sun, 30 Aug 2020 15:59:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A0062071B for ; Sun, 30 Aug 2020 15:59:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="HX+GJFDw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726105AbgH3P72 (ORCPT ); Sun, 30 Aug 2020 11:59:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725993AbgH3P71 (ORCPT ); Sun, 30 Aug 2020 11:59:27 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D914C061573; Sun, 30 Aug 2020 08:59:26 -0700 (PDT) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 281F1258; Sun, 30 Aug 2020 17:58:54 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1598803138; bh=/V6uJ2UaJxcf2LrkofPkuHLaZ/DO+zHrenXjUGNL5KA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HX+GJFDw2KI8ilmLOZtUtL7br3BsmXtFHmxTilbjKorOD10U3skl+k9V+HLn8r3Af k0Lx8Yj0cbRKnz/TQJya/84h10aqYCyW6/fNq4/MGMObVzHopFPYqSpXBcKjqBmUGq CJJjyevVTDTK5+YPc1ADTcx22nkwlA/KrsHc6ZUc= Date: Sun, 30 Aug 2020 18:58:33 +0300 From: Laurent Pinchart To: Guenter Roeck Cc: Mauro Carvalho Chehab , Sakari Ailus , linux-uvc-devel@lists.sourceforge.net, linux-usb@vger.kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5] media: uvcvideo: Fix race conditions Message-ID: <20200830155833.GA6043@pendragon.ideasonboard.com> References: <20200830150443.167286-1-linux@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200830150443.167286-1-linux@roeck-us.net> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Guenter, Thank you for the patches. On Sun, Aug 30, 2020 at 08:04:38AM -0700, Guenter Roeck wrote: > The uvcvideo code has no lock protection against USB disconnects > while video operations are ongoing. This has resulted in random > error reports, typically pointing to a crash in usb_ifnum_to_if(), > called from usb_hcd_alloc_bandwidth(). A typical traceback is as > follows. > > usb 1-4: USB disconnect, device number 3 > BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP PTI > CPU: 0 PID: 5633 Comm: V4L2CaptureThre Not tainted 4.19.113-08536-g5d29ca36db06 #1 > Hardware name: GOOGLE Edgar, BIOS Google_Edgar.7287.167.156 03/25/2019 > RIP: 0010:usb_ifnum_to_if+0x29/0x40 > Code: <...> > RSP: 0018:ffffa46f42a47a80 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff904a396c9000 > RDX: ffff904a39641320 RSI: 0000000000000001 RDI: 0000000000000000 > RBP: ffffa46f42a47a80 R08: 0000000000000002 R09: 0000000000000000 > R10: 0000000000009975 R11: 0000000000000009 R12: 0000000000000000 > R13: ffff904a396b3800 R14: ffff904a39e88000 R15: 0000000000000000 > FS: 00007f396448e700(0000) GS:ffff904a3ba00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000000 CR3: 000000016cb46000 CR4: 00000000001006f0 > Call Trace: > usb_hcd_alloc_bandwidth+0x1ee/0x30f > usb_set_interface+0x1a3/0x2b7 > uvc_video_start_transfer+0x29b/0x4b8 [uvcvideo] > uvc_video_start_streaming+0x91/0xdd [uvcvideo] > uvc_start_streaming+0x28/0x5d [uvcvideo] > vb2_start_streaming+0x61/0x143 [videobuf2_common] > vb2_core_streamon+0xf7/0x10f [videobuf2_common] > uvc_queue_streamon+0x2e/0x41 [uvcvideo] > uvc_ioctl_streamon+0x42/0x5c [uvcvideo] > __video_do_ioctl+0x33d/0x42a > video_usercopy+0x34e/0x5ff > ? video_ioctl2+0x16/0x16 > v4l2_ioctl+0x46/0x53 > do_vfs_ioctl+0x50a/0x76f > ksys_ioctl+0x58/0x83 > __x64_sys_ioctl+0x1a/0x1e > do_syscall_64+0x54/0xde > > While this is problem rarely observed in the field, it is relatively easy > to reproduce by adding msleep() calls into the code. > > I don't presume to claim that I found every issue, but this patch series > should fix at least the major problems. > > The patch series was tested exensively on a Chromebook running chromeos-4.19 > and on a Linux system running a v5.8.y based kernel. I'll review each patch individually, but I think 2/5, 4/5 and 5/5 should be handled in the V4L2 core, not the uvcvideo driver. Otherwise we would have to replicate that logic in all drivers, while I think it can easily be implemented in a generic fashion as previously discussed. > ---------------------------------------------------------------- > Guenter Roeck (5): > media: uvcvideo: Cancel async worker earlier > media: uvcvideo: Lock video streams and queues while unregistering > media: uvcvideo: Release stream queue when unregistering video device > media: uvcvideo: Protect uvc queue file operations against disconnect > media: uvcvideo: In uvc_v4l2_open, check if video device is registered > > drivers/media/usb/uvc/uvc_ctrl.c | 11 ++++++---- > drivers/media/usb/uvc/uvc_driver.c | 12 ++++++++++ > drivers/media/usb/uvc/uvc_queue.c | 32 +++++++++++++++++++++++++-- > drivers/media/usb/uvc/uvc_v4l2.c | 45 ++++++++++++++++++++++++++++++++++++-- > drivers/media/usb/uvc/uvcvideo.h | 1 + > 5 files changed, 93 insertions(+), 8 deletions(-) -- Regards, Laurent Pinchart