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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 4E8EAC433E2 for ; Thu, 18 Jun 2020 07:18:26 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 2442521532 for ; Thu, 18 Jun 2020 07:18:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="NOTGbi1J" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2442521532 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7B2BE6EAE3; Thu, 18 Jun 2020 07:17:35 +0000 (UTC) Received: from mail29.static.mailgun.info (mail29.static.mailgun.info [104.130.122.29]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8DA866E075 for ; Wed, 17 Jun 2020 13:43:29 +0000 (UTC) DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1592401412; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=0rJg/220vt9zUyvHiVMMZNyLy4HIJD5Z/P1Mdz9z7JQ=; b=NOTGbi1JicFRphWGpKkl/8COrAbeCaF1n8YKo5n5HYBMXQnThuGg3WxZwmGU4OUV6ItZK4ec hfaeRfv9nbfuJ8ozANDSUZ4CwVa7pGMX5skwR9usKpOk6IYcqhInvYsULWwX0Knyl9/LlsW3 Jam+mwgVnWcyQpQcHvRDyexJhe4= X-Mailgun-Sending-Ip: 104.130.122.29 X-Mailgun-Sid: WyJkOTU5ZSIsICJkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n10.prod.us-west-2.postgun.com with SMTP id 5eea1df64c9690533ae41b19 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 17 Jun 2020 13:43:18 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 991DBC43391; Wed, 17 Jun 2020 13:43:18 +0000 (UTC) Received: from [192.168.1.102] (unknown [183.83.143.239]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: charante) by smtp.codeaurora.org (Postfix) with ESMTPSA id 625E8C433C8; Wed, 17 Jun 2020 13:43:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 625E8C433C8 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=charante@codeaurora.org Subject: Re: [PATCH] dmabuf: use spinlock to access dmabuf->name To: David Laight , "Ruhl, Michael J" , Sumit Semwal , "open list:DMA BUFFER SHARING FRAMEWORK" , DRI mailing list References: <316a5cf9-ca71-6506-bf8b-e79ded9055b2@codeaurora.org> <14063C7AD467DE4B82DEDB5C278E8663010F365EF5@fmsmsx107.amr.corp.intel.com> <14063C7AD467DE4B82DEDB5C278E8663010F365F7D@fmsmsx107.amr.corp.intel.com> <5b960c9a-ef9d-b43d-716d-113efc793fe5@codeaurora.org> From: Charan Teja Kalla Message-ID: Date: Wed, 17 Jun 2020 19:13:12 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Mailman-Approved-At: Thu, 18 Jun 2020 07:17:31 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linaro MM SIG , "vinmenon@codeaurora.org" , LKML , "stable@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 6/17/2020 1:51 PM, David Laight wrote: > From: Charan Teja Kalla >> Sent: 17 June 2020 07:29 > ... >>>> If name is freed you will copy garbage, but the only way >>>> for that to happen is that _set_name or _release have to be called >>>> at just the right time. >>>> >>>> And the above would probably only be an issue if the set_name >>>> was called, so you will get NULL or a real name. >> >> And there exists a use-after-free to avoid which requires the lock. Say >> that memcpy() in dmabuffs_dname is in progress and in parallel _set_name >> will free the same buffer that memcpy is operating on. > > If the name is being looked at while the item is being freed > you almost certainly have much bigger problems that just > the name being a 'junk' pointer. True, thus needs the lock. > > David. > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > Registration No: 1397386 (Wales) > -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel