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 C8D04C433EF for ; Thu, 21 Apr 2022 12:06:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382981AbiDUMI7 (ORCPT ); Thu, 21 Apr 2022 08:08:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1382836AbiDUMI4 (ORCPT ); Thu, 21 Apr 2022 08:08:56 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B0F4EB7DE; Thu, 21 Apr 2022 05:06:06 -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 sin.source.kernel.org (Postfix) with ESMTPS id 02E44CE2173; Thu, 21 Apr 2022 12:06:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF6C5C385A5; Thu, 21 Apr 2022 12:06:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650542763; bh=E/KD3S9r1NY3AgCUpJ82Xa/0zscB5adhyxMkTD24z3A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=r2rskzI6gJ6hRu5OaS/sBRwhqp5o7RS7tvo7HCYMy66D2iYh4ci/7c98ABMWXWOVT NjnmGsaIdSLkbLNWlgzR6AOcesx+llDTJegDMKQeFxyK+5FsnlcL2R81gFkVVavErS EQK7JNBrkfJ44UIg05FYxduekli+vEdP/v33ScB8= Date: Thu, 21 Apr 2022 14:06:00 +0200 From: Greg KH To: Fu Zixuan Cc: 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 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