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=-11.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,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 DE258C433B4 for ; Fri, 21 May 2021 12:44:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD563613D8 for ; Fri, 21 May 2021 12:44:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233442AbhEUMpk (ORCPT ); Fri, 21 May 2021 08:45:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:59316 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229915AbhEUMpi (ORCPT ); Fri, 21 May 2021 08:45:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 09852613AC; Fri, 21 May 2021 12:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621601055; bh=+8u7Bzk+pS7SnmB3/zgIbs1kB0ko1X+1PDv2zvMy5rc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OAQBjQk781hK2nAwCB91P9kZUJVu9pWgJhBFj6bHcnhrGAAWY9i9WR7K96pHMnaYX CpIuL/Luwr4NGHULMNN9VzIyMalC0GzBFiruF/JdJQh5kyRE3yIT6uYogSy2J/asRk xhuqwAJ/koOQjIokjKVccDpA1CKHMgRztopYACXc= Date: Fri, 21 May 2021 14:44:13 +0200 From: Greg Kroah-Hartman To: Tong Zhang Cc: Arnd Bergmann , linux-kernel@vger.kernel.org, Colin Ian King Subject: Re: [PATCH v4] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge Message-ID: References: <20210518192820.181500-1-ztong0001@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210518192820.181500-1-ztong0001@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 18, 2021 at 03:28:18PM -0400, Tong Zhang wrote: > There is an issue with the ASPM(optional) capability checking function. > A device might be attached to root complex directly, in this case, > bus->self(bridge) will be NULL, thus priv->parent_pdev is NULL. > Since alcor_pci_init_check_aspm(priv->parent_pdev) checks the PCI link's > ASPM capability and populate parent_cap_off, which will be used later by > alcor_pci_aspm_ctrl() to dynamically turn on/off device, what we can do > here is to avoid checking the capability if we are on the root complex. > This will make pdev_cap_off 0 and alcor_pci_aspm_ctrl() will simply > return when bring called, effectively disable ASPM for the device. > > [ 1.246492] BUG: kernel NULL pointer dereference, address: 00000000000000c0 > [ 1.248731] RIP: 0010:pci_read_config_byte+0x5/0x40 > [ 1.253998] Call Trace: > [ 1.254131] ? alcor_pci_find_cap_offset.isra.0+0x3a/0x100 [alcor_pci] > [ 1.254476] alcor_pci_probe+0x169/0x2d5 [alcor_pci] > > Signed-off-by: Tong Zhang > Co-developed-by: Greg Kroah-Hartman > Co-developed-by: Colin Ian King > --- > v2: check before calling alcor_pci_find_cap_offset() > v3: Add comment. Enable the dev_dbg() output when priv->parent_pdev is NULL. > v4: fix inverted if statement, thanks to Colin Please just send a fix-up patch instead, I don't want to revert and then add this, that doesn't make any sense... thanks, greg k-h