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 DF4FFC433DB for ; Wed, 13 Jan 2021 07:22:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C8DC221EF for ; Wed, 13 Jan 2021 07:22:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726751AbhAMHVu (ORCPT ); Wed, 13 Jan 2021 02:21:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:53472 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726741AbhAMHVu (ORCPT ); Wed, 13 Jan 2021 02:21:50 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4B83E221E2; Wed, 13 Jan 2021 07:21:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610522470; bh=Mvi+9ZB26e7kwWopE/JrOTsi3ksANLPXPUSYb5Y1k/A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ojeS2YxspW2+lSL/fOIiIm+2HHH/r8w2ap0+lm0uyFxvRa8oU4rQ6M5gjd6ZUNVXj VBm/72SloxB1SPKHgrsgjHe84eW/MDP+1kx/Z3IgK+ZXkpiW9k2QPSepQOH/VTxdEp nbgT38xWkjgP8X86Jt/bUUsxEfwmzdj/bVnI0c5x/z/Rw791Imywl8TkmM1dV0yvi3 sDQwF99BXVxXschtabSpHWjwjarErv4wzf0Bc8N3uM4spmwKjP2brpqcnbydpwh8pf N2aLwnp92q9l0hhX8OGE7kRG/4kVBRU8s0JwN4TPPWrFeUovB66T0Gp5KdpzgSlzDx qtoZHNE3h/nnQ== Date: Wed, 13 Jan 2021 09:21:04 +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: <20210113072104.GH4678@unreal> References: <1610460145-14645-1-git-send-email-shradha.t@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1610460145-14645-1-git-send-email-shradha.t@samsung.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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