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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 603CEC433F5 for ; Tue, 31 May 2022 11:04:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SJPyKUofNTk8DHvpH4KGcZ4O6M4zkkpUa+580lVULv4=; b=mnFRoYsvC720F0 rEKkQPhnRMIoenvkkGQD2CKzxjH19WCOW6z6n58PH30Ost6y8GOGfWb4zlnTfrEatZlttzHHHpsLZ /gH/CraAUZNFTRZZWPKok3XqzZCM04MPgsuEnbX5fZq610z9Gf7poeXILJriRyrxr7v8piKySuSTf RL8JzlxXXwnuk8WMc2rpxQRvHqCFisPd2TNEiF2nbvWhrVPBl3/Z8Ge1SxlWITMTrHs7ZY3nHmmsr +dwvLYrsD1TO9DDJBZDH0nJd1nqsFrNKAA2kQEq7pJUmXPVJMpBD1W+hh2mGrbudzUt/DJ/pu4WHs saC/YkfUytG490NM6bZA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nvzeW-00AKFa-7d; Tue, 31 May 2022 11:03:08 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nvzeS-00AKEL-DD for linux-arm-kernel@lists.infradead.org; Tue, 31 May 2022 11:03:06 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8C23C23A; Tue, 31 May 2022 04:02:59 -0700 (PDT) Received: from [10.57.81.38] (unknown [10.57.81.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D57073F73D; Tue, 31 May 2022 04:02:58 -0700 (PDT) Message-ID: <1cdf5131-a67b-7297-ad75-49b53f2da293@arm.com> Date: Tue, 31 May 2022 12:02:53 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH 2/2] firmware: arm_scmi: Fix pointers arithmetic in Base protocol Content-Language: en-GB To: Cristian Marussi , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Sudeep Holla References: <20220530115237.277077-1-cristian.marussi@arm.com> <20220530115237.277077-2-cristian.marussi@arm.com> From: Robin Murphy In-Reply-To: <20220530115237.277077-2-cristian.marussi@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220531_040304_536689_D9A0E3D6 X-CRM114-Status: GOOD ( 14.92 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2022-05-30 12:52, Cristian Marussi wrote: > Fix a possible undefined behaviour involving pointer arithmetic in Base > protocol scmi_base_implementation_list_get(). > > cppcheck complains with: > > drivers/firmware/arm_scmi/base.c:190:19: warning: 't->rx.buf' is of type 'void *'. When using void pointers in calculations, the behaviour is undefined. [arithOperationsOnVoidPointer] > list = t->rx.buf + sizeof(*num_ret); Except we use GNU C, where it is well-defined[1]. We use void pointer arithmetic *all over* Linux, so there really isn't any valid argument that it could be problematic. If this was a common SCMI library intended to be portable then the patch would seem more reasonable, but in Linux-specific driver code it's just pointless churn. Cheers, Robin. [1] https://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html > Fixes: b6f20ff8bd94 ("firmware: arm_scmi: add common infrastructure and support for base protocol") > Cc: Sudeep Holla > Signed-off-by: Cristian Marussi > --- > drivers/firmware/arm_scmi/base.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c > index 20fba7370f4e..6d6214d9e68c 100644 > --- a/drivers/firmware/arm_scmi/base.c > +++ b/drivers/firmware/arm_scmi/base.c > @@ -187,7 +187,7 @@ scmi_base_implementation_list_get(const struct scmi_protocol_handle *ph, > > num_skip = t->tx.buf; > num_ret = t->rx.buf; > - list = t->rx.buf + sizeof(*num_ret); > + list = ((u8 *)t->rx.buf) + sizeof(*num_ret); > > do { > size_t real_list_sz; _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel