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=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 72EADC433ED for ; Tue, 11 May 2021 17:17:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B12561352 for ; Tue, 11 May 2021 17:17:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232019AbhEKRSk (ORCPT ); Tue, 11 May 2021 13:18:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232047AbhEKRSa (ORCPT ); Tue, 11 May 2021 13:18:30 -0400 Received: from mail-io1-xd2c.google.com (mail-io1-xd2c.google.com [IPv6:2607:f8b0:4864:20::d2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C1CAC061760 for ; Tue, 11 May 2021 10:17:23 -0700 (PDT) Received: by mail-io1-xd2c.google.com with SMTP id p11so18855284iob.9 for ; Tue, 11 May 2021 10:17:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=s1ikXxcqKrSHiqHbTxzG/b3SitTHUqs3FscUloJXfR0=; b=h0A/eHVWSfLs2iKG4oXHHlaLsntu794GokKbkIlThVusc6OKHjoxCz0TXmvu9M+bHQ 0BCDw0BFPt05lkSQbq/PhzYJWu1Wa7bYwiDAziNTMoybxeYuXnnyjA5FESAjXwui1weB 7JK4oktzP7/cbNL/KaI92yS4BJ2oy6+rn8hOE8FuCQQpIbE7+akpR7HOmbcjbP4s7sOo SaY7el/oa3BZAAhXGkdx4nhr97Pv5SyQoDzBhmmrzjLDAyjQGn+PCS71AMmT01JYmJhm i2YBnxdUJfZ4gtJoebS3LaGpiDz9gKsVe+WrqUg2tvyfZtwdHnuhxR5PkwpggqEhCxo+ NcNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=s1ikXxcqKrSHiqHbTxzG/b3SitTHUqs3FscUloJXfR0=; b=Ta3q+1M45LFAev0BbBSU2CRiScAfbKz/1ah6Szh8WGpXKH/yrS1HnX8zUA5Vq7Vjzc srISQC8cWD0lDMlO+kwPom5nsye9pSnmEdbajVntPfG8yMqLtyKN81V2X65R9kd1jV4f V3fPw/j/7AG2o+pPRRHPhwS4FzBhOUCDwZ/2OOvdLcHOX08fmpdI+/lEDC7/Dh1iHFQv HDCJdlNvci+4I1ctYOhu2aw0ysa3i+Ud+yMcLIqfP6ltlieCXVLuWOT1f/VaghLReaxj ZCnYPcUhCXoVCUnXX0hs4KFYavGv2X4hbbPQktJuHbtBCT4DiHCtoMZ+/aEb5eWsLpi5 ZC6w== X-Gm-Message-State: AOAM531yoVc87j7/q8tKiaz+L1q76i95niquZRoxgHsveINGyhcaoL4J kUFdxogIEQ07DgWx8izwb4VV51dY5sJW1WgxzKV4/qB2EYECzg== X-Google-Smtp-Source: ABdhPJy8wJE8JusWiz4Be/4kp5uvb0MYFBhn/psBH+2NbQeijNUEHwFfRq7b60MjOMc1i+07xz4lN1/A/WYzEw9mAhU= X-Received: by 2002:a02:6d09:: with SMTP id m9mr27964954jac.131.1620753442848; Tue, 11 May 2021 10:17:22 -0700 (PDT) MIME-Version: 1.0 References: <20210426220728.1230340-1-ztong0001@gmail.com> In-Reply-To: From: Tong Zhang Date: Tue, 11 May 2021 10:17:12 -0700 Message-ID: Subject: Re: [PATCH] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge To: Greg Kroah-Hartman Cc: Arnd Bergmann , open list Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 11, 2021 at 12:03 AM Greg Kroah-Hartman wrote: > > On Mon, May 10, 2021 at 03:20:02PM -0700, Tong Zhang wrote: > > On Mon, May 10, 2021 at 7:36 AM Greg Kroah-Hartman > > wrote: > > > > > > On Mon, Apr 26, 2021 at 06:07:27PM -0400, Tong Zhang wrote: > > > > the PCI bridge might be NULL, so we'd better check before use it > > > > > > I do not understand, how can pci ever be NULL? There is only 1 way this > > > > Hi Greg, > > I think the problem is with > > priv->parent_pdev = pdev->bus->self > > where bus->self can be NULL. when bus->self is NULL, calling > > How can bus->self be NULL? Hi Greg, Please correct me if I am wrong, when bus->self is not NULL, it means there is a bridge, However, a device can be directly attached to the port on the root complex. In this case, the bus->self is NULL. > Did you see this on a real system? How did you duplicate the error > listed here? I did this in QEMU. If QEMU is considered not real, then I haven't seen an alcor controller configured in this way in a real system. That being said, this kind of configuration is still legit IMHO. Best, - Tong > thanks, > > greg k-h