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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id f8sm3417150ilr.20.2021.04.16.16.03.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 16 Apr 2021 16:03:05 -0700 (PDT) Subject: Re: [PATCH RFC v3] media: em28xx: Fix race condition between open and init function To: Igor Torrente , mchehab@kernel.org Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, kernel test robot , syzbot+b2391895514ed9ef4a8e@syzkaller.appspotmail.com, Shuah Khan References: <20210415140724.15398-1-igormtorrente@gmail.com> From: Shuah Khan Message-ID: <49c44747-1f25-11a1-1132-abfe406955b2@linuxfoundation.org> Date: Fri, 16 Apr 2021 17:03:05 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/16/21 1:33 PM, Igor Torrente wrote: > > > On 4/15/21 2:25 PM, Shuah Khan wrote: >> On 4/15/21 8:07 AM, Igor Matheus Andrade Torrente wrote: >>> Fixes a race condition - for lack of a more precise term - between >>> em28xx_v4l2_open and em28xx_v4l2_init, by detaching the v4l2_dev, >>> media_pad and vdev structs from the em28xx_v4l2, and managing the >>> lifetime of those objects more dynamicaly. >>> >>> The race happens when a thread[1] - containing the em28xx_v4l2_init() >>> code - calls the v4l2_mc_create_media_graph(), and it return a error, >>> if a thread[2] - running v4l2_open() - pass the verification point >>> and reaches the em28xx_v4l2_open() before the thread[1] finishes >>> the deregistration of v4l2 subsystem, the thread[1] will free all >>> resources before the em28xx_v4l2_open() can process their things, >>> because the em28xx_v4l2_init() has the dev->lock. And all this lead >>> the thread[2] to cause a user-after-free. >>> >>> Reported-by: kernel test robot >>> Reported-and-tested-by: >>> syzbot+b2391895514ed9ef4a8e@syzkaller.appspotmail.com >>> Signed-off-by: Igor Matheus Andrade Torrente >>> --- >>> >>> V2: Add v4l2_i2c_new_subdev null check >>>      Deal with v4l2 subdevs dependencies >>> >>> V3: Fix link error when compiled as a module >>> >>> --- >>>   drivers/media/usb/em28xx/em28xx-camera.c |   4 +- >>>   drivers/media/usb/em28xx/em28xx-video.c  | 300 +++++++++++++++-------- >>>   drivers/media/usb/em28xx/em28xx.h        |   6 +- >>>   3 files changed, 209 insertions(+), 101 deletions(-) >>> >> >> The changes looks good to me. Have you tried building as a modules and >> running modprobes and rmmods? You can do that without a device. >> > > I tried and everything worked fine. > Thank you. Reviewed-by: Shuah Khan thanks, -- Shuah 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=-10.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 6065EC43460 for ; Fri, 16 Apr 2021 23:03:15 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D81E5610CC for ; Fri, 16 Apr 2021 23:03:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D81E5610CC Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-kernel-mentees-bounces@lists.linuxfoundation.org Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 823DB41894; Fri, 16 Apr 2021 23:03:14 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 3d5vgiQx862h; Fri, 16 Apr 2021 23:03:13 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp4.osuosl.org (Postfix) with ESMTP id 5BCBF41888; Fri, 16 Apr 2021 23:03:13 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 24134C000B; Fri, 16 Apr 2021 23:03:13 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6A49AC000A for ; Fri, 16 Apr 2021 23:03:11 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 3D29E41888 for ; Fri, 16 Apr 2021 23:03:11 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lljhIMKsyENO for ; Fri, 16 Apr 2021 23:03:07 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.8.0 Received: from mail-io1-xd29.google.com (mail-io1-xd29.google.com [IPv6:2607:f8b0:4864:20::d29]) by smtp4.osuosl.org (Postfix) with ESMTPS id 778D541870 for ; Fri, 16 Apr 2021 23:03:07 +0000 (UTC) Received: by mail-io1-xd29.google.com with SMTP id s16so23971704iog.9 for ; Fri, 16 Apr 2021 16:03:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=mh7KPhLlx4lKOuec3qu70zVXkFr1yF2gQQ0PQcauUIE=; b=UJFGZGUgrqrrouEiWcHMIoZhuhTGc+Ot0YkymlGxKSqKbjNjVbjm4SiG6aWsMaJpta GTKzjQdXOagv58okSyt2i6YIPbt23iXeJ0uoDafPSYycAhNuVGEnfN5GPTc22QWZ78w9 /It3/bnDylnpJbRnLQV+OegtKBc+ea1J2KEAQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=mh7KPhLlx4lKOuec3qu70zVXkFr1yF2gQQ0PQcauUIE=; b=UY0E6JvgeuwRvK01po+tG/oQTFATq3bjruBSL7l2wGr8GkbqUAAxjcIsqEW3XyfABS xxOLYcxOLiiJCI98xvz8WrYWsFJDkrqOH2nJWHJ4kIZwaD/7sqxGa5ujsMrvdbciREaP f5Xbst4zCG8f4iFeg8RGwVZNNmVd5Wf0XnB7mvXadkxPvk6Zw8wTl9Qm/OHTubazbDj2 ad+0qjigVxrbXysNPszdklljlwP3w4dO5Wnyqo3jpn43VyexNO5Evr5UaxCweQh3TTq2 cMYnqXIHMdU/vIk8w91DQoQIrage7bqQ2/Q+6SVjVlnjPQdRn/GP8Nf1U6uQ5TWKbyq9 t/mA== X-Gm-Message-State: AOAM531on9oMdhYu6Ul7bvbcxDEmbKgkSQSdSMJ4LrVyecqmPVXrzXwa Wc/HgySXCRci6QgUyLpfqEAA364Y X-Google-Smtp-Source: ABdhPJwzleM/3omurgCNaMjlaQDqHjAgQEP4qcU921wdzrTgDfEcZSteDh7nbh3eY3EvlxqnlaFkDQ== X-Received: by 2002:a02:9389:: with SMTP id z9mr6127773jah.60.1618614186189; Fri, 16 Apr 2021 16:03:06 -0700 (PDT) Received: from [192.168.1.112] (c-24-9-64-241.hsd1.co.comcast.net. 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