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 3BDD9C433EF for ; Thu, 28 Apr 2022 14:06:44 +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-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=AIb9RgPoMXx6Qe7kkLp8ANP9rOuJh1nFnr7pfkzQd1c=; b=d0CFKeIHu+WOdH eGei9HdtAxY88hX1USXdruW8/upN1tN8/J8qEdCbXZpy1wTiXOs7Js6EI/IiL93sxqJPCaAo4wTQf JaJnB3CzJeVdfv8l4i8K/uU3d6NDBc9T+J16QH4RBiGhf90nrUFLDJiYq7im6xHhabkal7Z8XU8Ib XB3oAB7pWEtm4Za2CC+WZ0HHOhNOjSHYQV0LzyBiCs+9voU1AxBA2gDw3qcmlyTa+524lzz0rOdr/ pfLu5jhDMj1QFCZF7lqmEcBj1F0f3ADBiprnlmcVWcNqUPgrVT9VPlzrkasBdDciI+q/MZoUZMQGv zbywjbJEUBFkyZ/oqPlQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nk4lr-007Jo7-F9; Thu, 28 Apr 2022 14:05:27 +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 1nk4bv-007Ek0-OA for linux-arm-kernel@lists.infradead.org; Thu, 28 Apr 2022 13:55:15 +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 DA19F1474; Thu, 28 Apr 2022 06:55:10 -0700 (PDT) Received: from bogus (unknown [10.57.11.83]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 36F683F5A1; Thu, 28 Apr 2022 06:55:09 -0700 (PDT) Date: Thu, 28 Apr 2022 14:55:04 +0100 From: Sudeep Holla To: Cristian Marussi Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.quinlan@broadcom.com, Jonathan.Cameron@huawei.com, f.fainelli@gmail.com, etienne.carriere@linaro.org, vincent.guittot@linaro.org, souvik.chakravarty@arm.com Subject: Re: [PATCH 04/22] firmware: arm_scmi: Validate BASE_DISCOVER_LIST_PROTOCOLS reply Message-ID: <20220428135504.lt3bjq4sz7uktca6@bogus> References: <20220330150551.2573938-1-cristian.marussi@arm.com> <20220330150551.2573938-5-cristian.marussi@arm.com> <20220428100729.qlzl5lkkn2r5u3ra@bogus> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220428_065511_914020_44D13C4C X-CRM114-Status: GOOD ( 27.24 ) 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Apr 28, 2022 at 02:45:07PM +0100, Cristian Marussi wrote: > On Thu, Apr 28, 2022 at 11:07:29AM +0100, Sudeep Holla wrote: > > On Wed, Mar 30, 2022 at 04:05:33PM +0100, Cristian Marussi wrote: > > > Do not blindly trust SCMI backend server reply about list of implemented > > > protocols, instead validate the reported length of the list of protocols > > > against the real payload size of the message reply. > > > > > > Fixes: b6f20ff8bd9 ("firmware: arm_scmi: add common infrastructure and support for base protocol") > > > Signed-off-by: Cristian Marussi > > > --- > > > drivers/firmware/arm_scmi/base.c | 21 +++++++++++++++++++++ > > > 1 file changed, 21 insertions(+) > > > > > > diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c > > > index f279146f8110..c1165d1282ef 100644 > > > --- a/drivers/firmware/arm_scmi/base.c > > > +++ b/drivers/firmware/arm_scmi/base.c > > > @@ -189,6 +189,9 @@ scmi_base_implementation_list_get(const struct scmi_protocol_handle *ph, > > > list = t->rx.buf + sizeof(*num_ret); > > > > > > do { > > > + size_t real_list_sz; > > > + u32 calc_list_sz; > > > + > > > /* Set the number of protocols to be skipped/already read */ > > > *num_skip = cpu_to_le32(tot_num_ret); > > > > > > @@ -202,6 +205,24 @@ scmi_base_implementation_list_get(const struct scmi_protocol_handle *ph, > > > break; > > > } > > > > > > + if (t->rx.len < (sizeof(u32) * 2)) { > > > + dev_err(dev, "Truncated reply - rx.len:%zd\n", > > > + t->rx.len); > > > + ret = -EPROTO; > > > + break; > > > + } > > > + > > > + real_list_sz = t->rx.len - sizeof(u32); > > > + calc_list_sz = ((loop_num_ret / sizeof(u32)) + > > > + !!(loop_num_ret % sizeof(u32))) * sizeof(u32); > > > > Any reason this can't be (loop_num_ret - 1) / sizeof(u32) + 1 ? > > > > At first sight could be fine with your easier version BUT what if loop_num_ret > is returned as zero ? > > real_list_sz should be ZERO length and calc_list_sz > > im my version: > > calc_list_sz = ((0/4) +!!(0%4)) * 4 ===>> 0 > > while in the simplified one gets calculated wrong: > > calc_list_sz = (0-1)/4 + 1 ====> 1 > > ...moreover being both loop_num_ret and calc_list_sz unsigned I am even > not so sure about implicit casting messing things up evenm more :D > > So I sticked to the more convoluted approach :D > > ....Have I missed something else ? > Right, but shouldn't we break if it 0 much earlier. It must not happen with your new logic and even if it does, wouldn't it be better to break earlier ? -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel