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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7892C433F5 for ; Fri, 12 Nov 2021 15:36:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCB8360F14 for ; Fri, 12 Nov 2021 15:36:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235522AbhKLPjq (ORCPT ); Fri, 12 Nov 2021 10:39:46 -0500 Received: from netrider.rowland.org ([192.131.102.5]:41505 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S235304AbhKLPjI (ORCPT ); Fri, 12 Nov 2021 10:39:08 -0500 Received: (qmail 33489 invoked by uid 1000); 12 Nov 2021 10:36:15 -0500 Date: Fri, 12 Nov 2021 10:36:15 -0500 From: Alan Stern To: Haimin Zhang Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, TCS Robot Subject: Re: [PATCH v3] USB: ehci_brcm_hub_control: improve port index sanitizing Message-ID: <20211112153615.GA32928@rowland.harvard.edu> References: <20211112094921.90496-1-tcs.kernel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211112094921.90496-1-tcs.kernel@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Fri, Nov 12, 2021 at 05:49:21PM +0800, Haimin Zhang wrote: > Due to (wIndex & 0xff) - 1 can get an integer greater than 0xf, this > can cause array index to be out of bounds since the size of array > port_status is 0xf. Using macro function HCS_N_PORTS() can return > a valid index less than 15. Macro function HCS_N_PORTS() is used > to obtain a valid port index by logical AND 0xf. > > Reported-by: TCS Robot > Signed-off-by: Haimin Zhang > --- > drivers/usb/host/ehci-brcm.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/host/ehci-brcm.c b/drivers/usb/host/ehci-brcm.c > index d3626bfa966b..d2bf7768349c 100644 > --- a/drivers/usb/host/ehci-brcm.c > +++ b/drivers/usb/host/ehci-brcm.c > @@ -62,8 +62,11 @@ static int ehci_brcm_hub_control( > u32 __iomem *status_reg; > unsigned long flags; > int retval, irq_disabled = 0; > + u32 temp; > > - status_reg = &ehci->regs->port_status[(wIndex & 0xff) - 1]; > + temp = (wIndex & 0xff) - 1; > + temp = HCS_N_PORTS(temp); This is a misuse of the HCS_N_PORTS macro; the fact that it works out okay is just a coincidence. That macro was intended for extracting the number of ports from the hcs_params word in the EHCI register space. It should not be used for any other purpose (including forcing a value to be in the range of valid port numbers). If you want to do this correctly, do something like: temp = min_t(u32, temp, HCS_N_PORTS_MAX - 1); Or even: if (temp >= HCS_N_PORTS_MAX) /* Force valid port number */ temp = 0; Alan Stern > + status_reg = &ehci->regs->port_status[temp]; > > /* > * RESUME is cleared when GetPortStatus() is called 20ms after start > -- > 2.30.1 (Apple Git-130)