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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 B0C8AC433E0 for ; Wed, 20 Jan 2021 05:33:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6FC8F2313C for ; Wed, 20 Jan 2021 05:33:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727354AbhATFcn (ORCPT ); Wed, 20 Jan 2021 00:32:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:34978 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731242AbhATFaK (ORCPT ); Wed, 20 Jan 2021 00:30:10 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 88DEF2311C; Wed, 20 Jan 2021 05:29:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611120569; bh=OOFp8zk9k64cA2yzlao8KtjRGH2xmQ6qvuD9AFDkcDw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bkDsSl0gzP76Ppo+xnBjytT2VkbLwIO5td7FVnv7ZIwah8r5mDE/5E9CzOJS27uq9 z02mbEszuSv7biDFCJ1/VG6Law9IpGCoG4rwj6U1CCT5FyM7hNwnfnDtGIjJ76rJfL nZs12+Qh2wMTj7w7VsuM4dR5VeaVmJq4dqOFAbAgXpUJTUmtg5u1Tu1yvfRxwRZWV/ SGvauH7p4WEz0tIJCdK8SYybd1Hj1jkiedN5BFwpH5D+HpzhdOnJ3uHGSyEmEdpirP 3gmn+IkSlC6P40JJg0PvBOWYTLEQwjheGu8O03Lje8I/OgmIRGHe3mw9Z3ydJuD0IY uImCVRHJi0i+Q== Date: Wed, 20 Jan 2021 07:29:25 +0200 From: Leon Romanovsky To: Shradha Todi Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, bhelgaas@google.com, kishon@ti.com, lorenzo.pieralisi@arm.com, pankaj.dubey@samsung.com, sriram.dash@samsung.com, niyas.ahmed@samsung.com, p.rajanbabu@samsung.com, l.mehra@samsung.com, hari.tv@samsung.com Subject: Re: [PATCH v4] PCI: endpoint: Fix NULL pointer dereference for ->get_features() Message-ID: <20210120052925.GL21258@unreal> References: <1610460145-14645-1-git-send-email-shradha.t@samsung.com> <20210113072104.GH4678@unreal> <147801d6ee49$2ecd2d30$8c678790$@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <147801d6ee49$2ecd2d30$8c678790$@samsung.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Jan 19, 2021 at 03:25:10PM +0530, Shradha Todi wrote: > > -----Original Message----- > > From: Leon Romanovsky > > Subject: Re: [PATCH v4] PCI: endpoint: Fix NULL pointer dereference for - > > >get_features() > > > > On Tue, Jan 12, 2021 at 07:32:25PM +0530, Shradha Todi wrote: > > > get_features ops of pci_epc_ops may return NULL, causing NULL pointer > > > dereference in pci_epf_test_bind function. Let us add a check for > > > pci_epc_feature pointer in pci_epf_test_bind before we access it to > > > avoid any such NULL pointer dereference and return -ENOTSUPP in case > > > pci_epc_feature is not found. > > > > > > When the patch is not applied and EPC features is not implemented in > > > the platform driver, we see the following dump due to kernel NULL > > > pointer dereference. > > > > > > [ 105.135936] Call trace: > > > [ 105.138363] pci_epf_test_bind+0xf4/0x388 [ 105.142354] > > > pci_epf_bind+0x3c/0x80 [ 105.145817] pci_epc_epf_link+0xa8/0xcc [ > > > 105.149632] configfs_symlink+0x1a4/0x48c [ 105.153616] > > > vfs_symlink+0x104/0x184 [ 105.157169] do_symlinkat+0x80/0xd4 [ > > > 105.160636] __arm64_sys_symlinkat+0x1c/0x24 [ 105.164885] > > > el0_svc_common.constprop.3+0xb8/0x170 > > > [ 105.169649] el0_svc_handler+0x70/0x88 [ 105.173377] > > > el0_svc+0x8/0x640 [ 105.176411] Code: d2800581 b9403ab9 f9404ebb > > > 8b394f60 (f9400400) [ 105.182478] ---[ end trace a438e3c5a24f9df0 > > > ]--- > > > > > > Description and call trace don't correlate with the proposed code change. > > > > The code in pci_epf_test_bind() doesn't dereference epc_features, at least > in > > direct manner. > > > > Thanks > > Thanks for the review. Yes, you're right. The dereference does not happen in > the pci_epf_test_bind() itself, but in pci_epf_test_alloc_space() being > called within. We will update the line "causing NULL pointer dereference in > pci_epf_test_bind function. " in the commit message to "causing NULL pointer > dereference in pci_epf_test_alloc_space function. " Would that be good > enough? I have no idea, just saw that the rest of the code at least partially prepared to deal with epc_features == NULL, maybe pci_epf_test_alloc_space() should be update to handle epc_features == NULL. Thanks >