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=-16.1 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, URIBL_BLOCKED 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 23847C49EA6 for ; Thu, 24 Jun 2021 15:27:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 045E4613DA for ; Thu, 24 Jun 2021 15:27:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232427AbhFXP3l (ORCPT ); Thu, 24 Jun 2021 11:29:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:52406 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231819AbhFXP3i (ORCPT ); Thu, 24 Jun 2021 11:29:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 50CB3613DA; Thu, 24 Jun 2021 15:27:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624548439; bh=9oXNZ4LONOItdd4Iwzgt2g0W7nQL9dFt8yuG4eI83PA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pimteVpqN76owi61qo8qtVG82hSx2tn1YevOIFbJLVwp1O0djvB3U2OUUd1o9W+X+ vcqDkjUk9nEkym/BIzsjNGXb2m1uGm0NR6avAC8C/ASvfDyMS50COYsiLxtLZM4fuM 0Br5GrSP3B1/S9F+JJxcjUs+TBiEbJDxiGbtmLBQ= Date: Thu, 24 Jun 2021 17:27:17 +0200 From: Greg KH To: Manivannan Sadhasivam Cc: hemantk@codeaurora.org, bbhatt@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, loic.poulain@linaro.org, stable@vger.kernel.org, Jeffrey Hugo Subject: Re: [PATCH 1/8] bus: mhi: core: Validate channel ID when processing command completions Message-ID: References: <20210621161616.77524-1-manivannan.sadhasivam@linaro.org> <20210621161616.77524-2-manivannan.sadhasivam@linaro.org> <20210624143248.GC6108@workstation> <20210624144752.GD6108@workstation> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210624144752.GD6108@workstation> Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Thu, Jun 24, 2021 at 08:17:52PM +0530, Manivannan Sadhasivam wrote: > On Thu, Jun 24, 2021 at 04:39:51PM +0200, Greg KH wrote: > > On Thu, Jun 24, 2021 at 08:02:48PM +0530, Manivannan Sadhasivam wrote: > > > On Thu, Jun 24, 2021 at 03:50:45PM +0200, Greg KH wrote: > > > > On Mon, Jun 21, 2021 at 09:46:09PM +0530, Manivannan Sadhasivam wrote: > > > > > From: Bhaumik Bhatt > > > > > > > > > > MHI reads the channel ID from the event ring element sent by the > > > > > device which can be any value between 0 and 255. In order to > > > > > prevent any out of bound accesses, add a check against the maximum > > > > > number of channels supported by the controller and those channels > > > > > not configured yet so as to skip processing of that event ring > > > > > element. > > > > > > > > > > Cc: stable@vger.kernel.org > > > > > Fixes: 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device") > > > > > Signed-off-by: Bhaumik Bhatt > > > > > Reviewed-by: Hemant Kumar > > > > > Reviewed-by: Manivannan Sadhasivam > > > > > Reviewed-by: Jeffrey Hugo > > > > > Link: https://lore.kernel.org/r/1619481538-4435-1-git-send-email-bbhatt@codeaurora.org > > > > > Signed-off-by: Manivannan Sadhasivam > > > > > --- > > > > > drivers/bus/mhi/core/main.c | 15 ++++++++++----- > > > > > 1 file changed, 10 insertions(+), 5 deletions(-) > > > > > > > > > > diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c > > > > > index 22acde118bc3..ed07421c4870 100644 > > > > > --- a/drivers/bus/mhi/core/main.c > > > > > +++ b/drivers/bus/mhi/core/main.c > > > > > @@ -773,11 +773,16 @@ static void mhi_process_cmd_completion(struct mhi_controller *mhi_cntrl, > > > > > cmd_pkt = mhi_to_virtual(mhi_ring, ptr); > > > > > > > > > > chan = MHI_TRE_GET_CMD_CHID(cmd_pkt); > > > > > - mhi_chan = &mhi_cntrl->mhi_chan[chan]; > > > > > - write_lock_bh(&mhi_chan->lock); > > > > > - mhi_chan->ccs = MHI_TRE_GET_EV_CODE(tre); > > > > > - complete(&mhi_chan->completion); > > > > > - write_unlock_bh(&mhi_chan->lock); > > > > > + WARN_ON(chan >= mhi_cntrl->max_chan); > > > > > > > > What can ever trigger this WARN_ON()? Do you mean to reboot a machine > > > > if panic-on-warn is set? > > > > > > > > If this can actually happen, then check for it and recover properly, > > > > don't just blindly warn and then keep on going. > > > > > > > > > > We can't do much here other than warning the user and dropping the > > > command. > > > > But you didn't warn anyone. Well, you rebooted the machine, is that ok? > > If this can be triggered by a user, this should never happen. > > > > Do not use WARN_ON() ever please. > > > > > There is no recovery possible because, the device has sent the command > > > completion event on a wrong channel. It can't happen usually unless a > > > malcious device sits on the other end. > > > > Then just eat the message and move on, please do not crash the box. > > > > Okay. We'll spit an error message and drop the event. If this can be triggered by a user, don't provide a way to DoS the kernel error log. thanks, greg k-h