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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 0A676C43381 for ; Wed, 13 Mar 2019 13:35:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CEC50214AE for ; Wed, 13 Mar 2019 13:35:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726654AbfCMNf4 (ORCPT ); Wed, 13 Mar 2019 09:35:56 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:57742 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725868AbfCMNf4 (ORCPT ); Wed, 13 Mar 2019 09:35:56 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4F29CA78; Wed, 13 Mar 2019 06:35:55 -0700 (PDT) Received: from [10.1.196.69] (e112269-lin.cambridge.arm.com [10.1.196.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A7D663F59C; Wed, 13 Mar 2019 06:35:53 -0700 (PDT) Subject: Re: [PATCH v2] media: rga: fix NULL pointer dereferences and a memory leak To: Kangjie Lu Cc: Heiko Stuebner , Jacob chen , linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, pakki001@umn.edu, Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org References: <6fc9f670-a199-b83d-ff0a-d4cdb8cb80d1@arm.com> <20190312065824.19646-1-kjlu@umn.edu> From: Steven Price Message-ID: Date: Wed, 13 Mar 2019 13:35:51 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190312065824.19646-1-kjlu@umn.edu> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/03/2019 06:58, Kangjie Lu wrote: > In case __get_free_pages fails, the fix releases resources and > return -ENOMEM to avoid NULL pointer dereferences. > > Also, the fix frees pages when video_register_device fails to > avoid a memory leak. > > Signed-off-by: Kangjie Lu > --- > drivers/media/platform/rockchip/rga/rga.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c > index 5c653287185f..307b7ab0ab64 100644 > --- a/drivers/media/platform/rockchip/rga/rga.c > +++ b/drivers/media/platform/rockchip/rga/rga.c > @@ -892,8 +892,17 @@ static int rga_probe(struct platform_device *pdev) > > rga->src_mmu_pages = > (unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3); > + if (!rga->src_mmu_pages) { > + ret = -ENOMEM; > + goto rel_vdev; > + } > + > rga->dst_mmu_pages = > (unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3); > + if (!rga->dst_mmu_pages) { > + ret = -ENOMEM; > + goto free_dst_pages; > + } > > def_frame.stride = (def_frame.width * def_frame.fmt->depth) >> 3; > def_frame.size = def_frame.stride * def_frame.height; > @@ -901,7 +910,7 @@ static int rga_probe(struct platform_device *pdev) > ret = video_register_device(vfd, VFL_TYPE_GRABBER, -1); > if (ret) { > v4l2_err(&rga->v4l2_dev, "Failed to register video device\n"); > - goto rel_vdev; > + goto free_pages; > } > > v4l2_info(&rga->v4l2_dev, "Registered %s as /dev/%s\n", > @@ -909,6 +918,10 @@ static int rga_probe(struct platform_device *pdev) > > return 0; > > +free_pages: > + free_pages((unsigned long)rga->src_mmu_pages, 3); > +free_dst_pages: > + free_pages((unsigned long)rga->dst_mmu_pages, 3); > rel_vdev: > video_device_release(vfd); > unreg_video_dev: That looks good. However looking into the error path more closely it appears that this was already rather broken. Here's the original: > rel_vdev: > video_device_release(vfd); > unreg_video_dev: > video_unregister_device(rga->vfd); > unreg_v4l2_dev: > v4l2_device_unregister(&rga->v4l2_dev); > err_put_clk: > pm_runtime_disable(rga->dev); video_device_release() is simply a call to kfree(), but video_unregister_device will then be called with the same pointer (rga->vfd is set to vfd further up). Which will then cause a use-after-free on the pointer. It might be a good idea to test this error path, for example make the video_register_device() call always fail and run with memory debuggers enabled (e.g. CONFIG_KASAN or CONFIG_DEBUG_KMEM_LEAK). Steve