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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 B97AEC433ED for ; Wed, 12 May 2021 06:24:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8161261925 for ; Wed, 12 May 2021 06:24:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229994AbhELGZj (ORCPT ); Wed, 12 May 2021 02:25:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:48066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229580AbhELGZi (ORCPT ); Wed, 12 May 2021 02:25:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8950561925; Wed, 12 May 2021 06:24:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620800671; bh=3TcRa33K/NKOSBtkiULfYg595iLod8JVM7DZRu7oqcY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1b1EuxAwFNg+ROt+RhwezcnnwykVsdNNunrVHlHeFBC98NCQ+1D5v2AzvacYUcKLa Q+akqB7gFspXDaXRzq7wOpWSQuiv8+1/lV0QgpntwudFx5AC3B4mev4gTTrD9V0Aoa WLy+HdgqjhRsqVcJZYRA7Vk/KrfZsrYYRCigaWRY= Date: Wed, 12 May 2021 08:24:28 +0200 From: Greg Kroah-Hartman To: Tong Zhang Cc: Arnd Bergmann , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge Message-ID: References: <20210511212937.1269191-1-ztong0001@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210511212937.1269191-1-ztong0001@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 11, 2021 at 05:29:38PM -0400, Tong Zhang wrote: > Device might be attached to root complex directly. In this case, > bus->self(bridge) will be NULL, so we'd better check before use it > > [ 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 > --- > v2: check before calling alcor_pci_find_cap_offset() > > drivers/misc/cardreader/alcor_pci.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/misc/cardreader/alcor_pci.c b/drivers/misc/cardreader/alcor_pci.c > index cd402c89189e..175c6b06f7aa 100644 > --- a/drivers/misc/cardreader/alcor_pci.c > +++ b/drivers/misc/cardreader/alcor_pci.c > @@ -139,6 +139,9 @@ static void alcor_pci_init_check_aspm(struct alcor_pci_priv *priv) > u32 val32; > > priv->pdev_cap_off = alcor_pci_find_cap_offset(priv, priv->pdev); > + > + if (!priv->parent_pdev) > + return; That feels wrong, you just prevented all of the remaining logic in this call to not be set up. Did you test this and did the driver and device still work properly if it hits this check? thanks, greg k-h