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 B6565C433F5 for ; Thu, 24 Feb 2022 20:00:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234131AbiBXUBN (ORCPT ); Thu, 24 Feb 2022 15:01:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232224AbiBXUBN (ORCPT ); Thu, 24 Feb 2022 15:01:13 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EE472763F9; Thu, 24 Feb 2022 12:00:43 -0800 (PST) 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 B3B91B82684; Thu, 24 Feb 2022 20:00:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6924C340E9; Thu, 24 Feb 2022 20:00:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1645732840; bh=SQaeb0Kta1h/s7fQ+4T22hNjVzetgs4lJusjv4G1iW0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aax4l6Htvnug8mbTTCX0X2rLTjQUq6JeR+ueffcTenNILwwCX0flGWbvC3gLcJ6tA LIh0hvw+Bbd4wOD+R8WWkcXInjD/9/0jYzDDCJgngg0AP70xSThZhi+xoRqNk2k57S CZRuK6sIXueEnpj9OiYbnawB7IF086gcluUXoeYhoLInJcsG3QP8kljM56vsMmO0nL /YS4U7y0DFUMJwrxWivKuA85OBpeIBAp3XuUSCNqMoGWt7d6xBjNGn0zesXPqr7gIX eMs+OPAknzWIlasB15qWJ+spE8ujhHQYTziWSeHJ7iJl0ihM5++9OEaRHnYQt8UNyK pgum76xmSyGAg== Date: Thu, 24 Feb 2022 14:08:39 -0600 From: "Gustavo A. R. Silva" To: Jeff Johnson Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, Kalle Valo , "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH 4/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_connect_event Message-ID: <20220224200839.GA1292927@embeddedor> References: <8a0e347615a3516980fd8b6ad2dc4864a880613b.1645583264.git.gustavoars@kernel.org> <6106494b-a1b3-6b57-8b44-b9528127533b@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6106494b-a1b3-6b57-8b44-b9528127533b@quicinc.com> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Wed, Feb 23, 2022 at 04:50:18PM -0800, Jeff Johnson wrote: > On 2/22/2022 6:38 PM, Gustavo A. R. Silva wrote: > > Replace one-element array with flexible-array member in struct > > wmi_connect_event. > > > > It's also worth noting that due to the flexible array transformation, > > the size of struct wmi_connect_event changed (now the size is 1 byte > > smaller), and in order to preserve the logic of before the transformation, > > the following change is needed: > > > > - if (len < sizeof(struct wmi_connect_event)) > > + if (len <= sizeof(struct wmi_connect_event)) > > > > This issue was found with the help of Coccinelle and audited and fixed, > > manually. > > > > Link: https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays > > Link: https://github.com/KSPP/linux/issues/79 > > Signed-off-by: Gustavo A. R. Silva > > --- > > Hi! > > > > It'd be great if someone can confirm or comment on the following > > changes described in the changelog text: > > > > - if (len < sizeof(struct wmi_connect_event)) > > + if (len <= sizeof(struct wmi_connect_event)) > > > > Thanks > > > > drivers/net/wireless/ath/ath6kl/wmi.c | 2 +- > > drivers/net/wireless/ath/ath6kl/wmi.h | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/net/wireless/ath/ath6kl/wmi.c b/drivers/net/wireless/ath/ath6kl/wmi.c > > index 049d75f31f3c..ccdccead688e 100644 > > --- a/drivers/net/wireless/ath/ath6kl/wmi.c > > +++ b/drivers/net/wireless/ath/ath6kl/wmi.c > > @@ -857,7 +857,7 @@ static int ath6kl_wmi_connect_event_rx(struct wmi *wmi, u8 *datap, int len, > > struct wmi_connect_event *ev; > > u8 *pie, *peie; > > - if (len < sizeof(struct wmi_connect_event)) > > + if (len <= sizeof(struct wmi_connect_event)) > > this is another case where IMO the original code can remain since all it is > really checking is to see if the entire "fixed" portion is present. in > reality if there was just one byte of assoc_info the response would actually > be invalid. I see; that's actually what I needed to be clarified. I wasn't sure if a channel list with no channels was valid and expected. Now I see it is. :) > what is missing is logic that verifies len is large enough to hold the > payload that is advertised via the beacon_ie_len, assoc_req_len, & > assoc_resp_len members. without this even if you change the initial len > check you can have a condition where len says there is one u8 in assoc_info > (and pass the initial test) but the other three members indicate that much > more data is present. > > but that is a pre-existing shortcoming that should be handled with a > separate patch. Yeah; I'll consider extending this series to include a patch for that. > > return -EINVAL; > > ev = (struct wmi_connect_event *) datap; > > diff --git a/drivers/net/wireless/ath/ath6kl/wmi.h b/drivers/net/wireless/ath/ath6kl/wmi.h > > index 432e4f428a4a..6b064e669d87 100644 > > --- a/drivers/net/wireless/ath/ath6kl/wmi.h > > +++ b/drivers/net/wireless/ath/ath6kl/wmi.h > > @@ -1545,7 +1545,7 @@ struct wmi_connect_event { > > u8 beacon_ie_len; > > u8 assoc_req_len; > > u8 assoc_resp_len; > > - u8 assoc_info[1]; > > + u8 assoc_info[]; > > } __packed; > > /* Disconnect Event */ > > whether or not you modify the length check consider this: > Reviewed-by: Jeff Johnson Great. :) Thanks a lot for the feedback! -- Gustavo