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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5011EC4332F for ; Thu, 21 Apr 2022 16:24:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230273AbiDUQ1Y (ORCPT ); Thu, 21 Apr 2022 12:27:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33828 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230140AbiDUQOf (ORCPT ); Thu, 21 Apr 2022 12:14:35 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A08682B241; Thu, 21 Apr 2022 09:11:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 64EBFB8272D; Thu, 21 Apr 2022 16:11:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8369BC385AA; Thu, 21 Apr 2022 16:11:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650557503; bh=0JZ8f5SuXJ/CklPHPrBpcIh6GJ/eB2k4giZBAKjN4wg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=x1kq33rOex4y1oHLsbmshJ2D6M+8KNZQhsRDXKK7+sSLl0AMXrsR+wlZzUifBl/Jk ZXZRzNXQSjAZzmiGeDrjmrZIhcNFEGhI37q0L5xd7qz1PiUZcEuRr9rEIPBv1vZ4k/ 1MPi0jfzeJ/zoifBfcXa4/tIM9IAuf/5Q34gdCW4= Date: Thu, 21 Apr 2022 18:11:39 +0200 From: Greg KH To: Mathias Nyman Cc: Fu Zixuan , Heiner Kallweit , mathias.nyman@intel.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, TOTE Robot Subject: Re: [PATCH] drivers: usb: host: fix NULL pointer dereferences triggered by unhandled errors in xhci_create_rhub_port_array() Message-ID: References: <20220421094236.1052170-1-r33s3n6@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 21, 2022 at 03:52:40PM +0300, Mathias Nyman wrote: > On 21.4.2022 15.21, Fu Zixuan wrote: > > On Thu, 21 Apr 2022 at 20:06, Greg KH wrote: > >> > >> On Thu, Apr 21, 2022 at 07:55:28PM +0800, Fu Zixuan wrote: > >>> On Thu, 21 Apr 2022 at 18:07, Greg KH wrote: > >>>> > >>>> On Thu, Apr 21, 2022 at 05:42:36PM +0800, Zixuan Fu wrote: > >>>>> In xhci_create_rhub_port_array(), when rhub->num_ports is zero, > >>>>> rhub->ports would not be set; when kcalloc_node() fails, rhub->ports > >>>>> would be set to NULL. In these two cases, xhci_create_rhub_port_array() > >>>>> just returns void, and thus its callers are unaware of the error. > >>>>> > >>>>> Then rhub->ports is dereferenced in xhci_usb3_hub_descriptor() or > >>>>> xhci_usb2_hub_descriptor(). > >>>>> > >>>>> To fix the bug, xhci_setup_port_arrays() should return an integer to > >>>>> indicate a possible error, and its callers should handle the error. > >>>>> > >>>>> Here is the log when this bug occurred in our fault-injection testing: > >>>>> > >>>>> [ 24.001309] BUG: kernel NULL pointer dereference, address: 0000000000000000 > >>>>> ... > >>>>> [ 24.003992] RIP: 0010:xhci_hub_control+0x3f5/0x60d0 [xhci_hcd] > >>>>> ... > >>>>> [ 24.009803] Call Trace: > >>>>> [ 24.010014] > >>>>> [ 24.011310] usb_hcd_submit_urb+0x1233/0x1fd0 > >>>>> [ 24.017071] usb_start_wait_urb+0x115/0x310 > >>>>> [ 24.017641] usb_control_msg+0x28a/0x450 > >>>>> [ 24.019046] hub_probe+0xb16/0x2320 > >>>>> [ 24.019757] usb_probe_interface+0x4f1/0x930 > >>>>> [ 24.019765] really_probe+0x33d/0x970 > >>>>> [ 24.019768] __driver_probe_device+0x157/0x210 > >>>>> [ 24.019772] driver_probe_device+0x4f/0x340 > >>>>> [ 24.019775] __device_attach_driver+0x2ee/0x3a0 > >>>>> ... > >>>>> > >>>>> Reported-by: TOTE Robot > >>>>> Signed-off-by: Zixuan Fu > >>>>> --- > >>>>> drivers/usb/host/xhci-mem.c | 17 ++++++++++++----- > >>>>> 1 file changed, 12 insertions(+), 5 deletions(-) > >>>>> > >>>>> diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c > >>>>> index bbb27ee2c6a3..024515346c39 100644 > >>>>> --- a/drivers/usb/host/xhci-mem.c > >>>>> +++ b/drivers/usb/host/xhci-mem.c > >>>>> @@ -2235,7 +2235,7 @@ static void xhci_add_in_port(struct xhci_hcd *xhci, unsigned int num_ports, > >>>>> /* FIXME: Should we disable ports not in the Extended Capabilities? */ > >>>>> } > >>>>> > >>>>> -static void xhci_create_rhub_port_array(struct xhci_hcd *xhci, > >>>>> +static int xhci_create_rhub_port_array(struct xhci_hcd *xhci, > >>>>> struct xhci_hub *rhub, gfp_t flags) > >>>>> { > >>>>> int port_index = 0; > >>>>> @@ -2243,11 +2243,11 @@ static void xhci_create_rhub_port_array(struct xhci_hcd *xhci, > >>>>> struct device *dev = xhci_to_hcd(xhci)->self.sysdev; > >>>>> > >>>>> if (!rhub->num_ports) > >>>>> - return; > >>>>> + return -EINVAL; > >>>>> rhub->ports = kcalloc_node(rhub->num_ports, sizeof(*rhub->ports), > >>>>> flags, dev_to_node(dev)); > >>>>> if (!rhub->ports) > >>>>> - return; > >>>>> + return -ENOMEM; > >>>>> > >>>>> for (i = 0; i < HCS_MAX_PORTS(xhci->hcs_params1); i++) { > >>>>> if (xhci->hw_ports[i].rhub != rhub || > >>>>> @@ -2259,6 +2259,7 @@ static void xhci_create_rhub_port_array(struct xhci_hcd *xhci, > >>>>> if (port_index == rhub->num_ports) > >>>>> break; > >>>>> } > >>>>> + return 0; > >>>>> } > >>>>> > >>>>> /* > >>>>> @@ -2277,6 +2278,7 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags) > >>>>> int cap_count = 0; > >>>>> u32 cap_start; > >>>>> struct device *dev = xhci_to_hcd(xhci)->self.sysdev; > >>>>> + int ret; > >>>>> > >>>>> num_ports = HCS_MAX_PORTS(xhci->hcs_params1); > >>>>> xhci->hw_ports = kcalloc_node(num_ports, sizeof(*xhci->hw_ports), > >>>>> @@ -2367,8 +2369,13 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags) > >>>>> * Not sure how the USB core will handle a hub with no ports... > >>>>> */ > >>>>> > >>>>> - xhci_create_rhub_port_array(xhci, &xhci->usb2_rhub, flags); > >>>>> - xhci_create_rhub_port_array(xhci, &xhci->usb3_rhub, flags); > >>>>> + ret = xhci_create_rhub_port_array(xhci, &xhci->usb2_rhub, flags); > >>>>> + if (ret) > >>>>> + return ret; > >>>>> + > >>>>> + ret = xhci_create_rhub_port_array(xhci, &xhci->usb3_rhub, flags); > >>>>> + if (ret) > >>>>> + return ret; > >>>> > >>>> What about the memory allocated by the first call to > >>>> xhci_create_rhub_port_array()? Is that now lost? Same for everything > >>>> else allocated before these calls, how is that cleaned up properly? > >>>> > >>>> thanks, > >>>> > >>>> greg k-h > >>> > >>> Thanks for your swift reply. We understand your concern. In fact, we have > >>> checked the related code carefully and found that xhci_create_rhub_port_array() > >>> is only used in xhci_setup_port_arrays(). Moreover, only xhci_mem_init() calls > >>> xhci_setup_port_arrays() and does all cleanup work when it fails. Specifically, > >>> xhci_mem_init() calls xhci_mem_cleanup(), which eventually called > >>> kfree(xhci->usb2_rhub.ports) and kfree(xhci->usb3_rhub.ports). > >> > >> Great, can you mention this in the changelog text to show that you have > >> thought this through and it can be documented as such? > >> > >> thanks, > >> > >> greg k-h > > > > Thanks for your reply! We will do that and submit the patch v2 soon. > > > > Good to get this fixed, but there's a series by Heiner Kallweit that adds support > for xHC controllers with just one roothub [1]. > It will conflict with this. > > We might need to change this a bit so that this can go to stable alone, but still > being being able to somewhat neatly apply that new series on top of this. As this is not anything a normal user will ever hit, it should be redone on top of your xhci changes as it's not needed in any stable tree. thanks, greg k-h