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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B5C4C3DA7A for ; Tue, 3 Jan 2023 01:34:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231216AbjACBeK (ORCPT ); Mon, 2 Jan 2023 20:34:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49392 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233786AbjACBeG (ORCPT ); Mon, 2 Jan 2023 20:34:06 -0500 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 154A9E7C for ; Mon, 2 Jan 2023 17:34:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1672709646; x=1704245646; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=6guush2vfOoBc9v6cMZa7A/f9x+xz+VSebDHnSj7k/k=; b=e24/Y9hKGtfo01N7fjlJb9q+ERetUJH/rbQ8HcXzEhIklLQILu6GfrZp rwjqR5WmJYRMKk/Yi7hX8VaFDU/K1g/Cxunk2oD56OjPOgRgdMPVzyr0T qUaO6XbNhjiR6BronoVRW7jXtE3h1hGWvWpuax3qCghv0n/kK3KaBPtIV pXSgNUH7Z+iHHgklbBzZnW3OhJnCXP03+iPbwut8I/SSFVygkkMBUWkSs 37jun/WHM2G0vI62QETknH8HIzefvxCEpybL9M1dzynjpLtOb9R5tgDOG FJyI22kVaN4vpqCwJM/6WYbvsdKKcNIprfu3lF6roScOFh8RV0cQ+X14O Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10578"; a="301247130" X-IronPort-AV: E=Sophos;i="5.96,295,1665471600"; d="scan'208";a="301247130" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jan 2023 17:34:05 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10578"; a="983417229" X-IronPort-AV: E=Sophos;i="5.96,295,1665471600"; d="scan'208";a="983417229" Received: from allen-box.sh.intel.com (HELO [10.239.159.48]) ([10.239.159.48]) by fmsmga005.fm.intel.com with ESMTP; 02 Jan 2023 17:34:03 -0800 Message-ID: Date: Tue, 3 Jan 2023 09:26:19 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Cc: baolu.lu@linux.intel.com Subject: Re: [PATCH] iommu: Fix refcount leak in iommu_device_claim_dma_owner To: Miaoqian Lin , Joerg Roedel , Will Deacon , Robin Murphy , Kevin Tian , Eric Auger , Jason Gunthorpe , iommu@lists.linux.dev, linux-kernel@vger.kernel.org References: <20221230083100.1489569-1-linmq006@gmail.com> Content-Language: en-US From: Baolu Lu In-Reply-To: <20221230083100.1489569-1-linmq006@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/30/22 4:31 PM, Miaoqian Lin wrote: > iommu_group_get() returns the group with the reference incremented. > Move iommu_group_get() after owner check to fix the refcount leak. An empty @owner is a more serious problem than refcount leak. It should not happen, so a WARN_ON() was added there. Anyway, your change makes the code better. > > Fixes: 89395ccedbc1 ("iommu: Add device-centric DMA ownership interfaces") > Signed-off-by: Miaoqian Lin > --- > drivers/iommu/iommu.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index de91dd88705b..3a7dd8b61fab 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -3185,14 +3185,16 @@ EXPORT_SYMBOL_GPL(iommu_group_claim_dma_owner); > */ > int iommu_device_claim_dma_owner(struct device *dev, void *owner) > { > - struct iommu_group *group = iommu_group_get(dev); > + struct iommu_group *group = NULL; No need to set NULL to group. > int ret = 0; > > - if (!group) > - return -ENODEV; > if (WARN_ON(!owner)) > return -EINVAL; > > + group = iommu_group_get(dev); > + if (!group) > + return -ENODEV; > + > mutex_lock(&group->mutex); > if (group->owner_cnt) { > if (group->owner != owner) { Others look good to me. Reviewed-by: Lu Baolu -- Best regards, baolu