From patchwork Thu Mar 30 01:54:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 13193344 X-Patchwork-Delegate: gustavo@embeddedor.com 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 18325C74A5B for ; Thu, 30 Mar 2023 01:53:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229605AbjC3Bxe (ORCPT ); Wed, 29 Mar 2023 21:53:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229586AbjC3Bxd (ORCPT ); Wed, 29 Mar 2023 21:53:33 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 393B09F; Wed, 29 Mar 2023 18:53:32 -0700 (PDT) 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 C6159B82581; Thu, 30 Mar 2023 01:53:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EA94C433EF; Thu, 30 Mar 2023 01:53:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1680141209; bh=3XmANaFzBt3a+2sASRW3pZzJKWGwytosBj+PU3cNreY=; h=Date:From:To:Cc:Subject:From; b=vBpMJ4k4UCgp74JR3KKcFqw9mZDJn651IODDcgfoSH2hVylUD6bbLyLUTq23qYkLS o718vQ/9nOb+TcuEbi9fRfq26mS3I1l8Z5ztvcZJetA8asvxeqbQ+qJGbgT9tWcX4N zOuz1BZxX6+xqHdJpJscAfZjhyPBXEK0nflyuNgUqCfCpo9l/5m19fgp/VzMb8RiUA VeR5nzuJsAw9J6o3vIKtboOWRVq4HU3tVnGA0YL4lP7TKC3mkyqkd/WT+pio3FTNd3 sU5dKfZAN7XjBTZCirUCBQ+bRcn23bRSQ7ZoDVD688i2NaMZ/rSAM1XReEQPlDNqMe YaV7a3Ur/53vg== Date: Wed, 29 Mar 2023 19:54:02 -0600 From: "Gustavo A. R. Silva" To: Benson Leung , Guenter Roeck Cc: chrome-platform@lists.linux.dev, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH][next] platform/chrome: Fix -Warray-bounds warnings Message-ID: MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org GCC-13 (and Clang) does not like having a partially allocated object, since it cannot reason about it for bounds checking. Notice that the compiler is legitimately complaining about accessing an object (params, in this case) for which not enough memory was allocated. The object is of size 20 bytes: struct ec_params_vbnvcontext { uint32_t op; /* 0 4 */ uint8_t block[16]; /* 4 16 */ /* size: 20, cachelines: 1, members: 2 */ /* last cacheline: 20 bytes */ }; but only 16 bytes are allocated: sizeof(struct ec_response_vbnvcontext) == 16 In this case, as only enough space for the op field is allocated, we can use an object of type uint32_t instead of a whole struct ec_params_vbnvcontext (for which not enough memory is allocated). Fix the following warning seen under GCC 13: drivers/platform/chrome/cros_ec_vbc.c: In function ‘vboot_context_read’: drivers/platform/chrome/cros_ec_vbc.c:36:15: warning: array subscript ‘struct ec_params_vbnvcontext[1]’ is partly outside array bounds of ‘unsigned char[36]’ [-Warray-bounds=] 36 | params->op = EC_VBNV_CONTEXT_OP_READ; | ^~ In file included from drivers/platform/chrome/cros_ec_vbc.c:12: In function ‘kmalloc’, inlined from ‘vboot_context_read’ at drivers/platform/chrome/cros_ec_vbc.c:30:8: ./include/linux/slab.h:580:24: note: at offset 20 into object of size 36 allocated by ‘kmalloc_trace’ 580 | return kmalloc_trace( | ^~~~~~~~~~~~~~ 581 | kmalloc_caches[kmalloc_type(flags)][index], | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 582 | flags, size); | ~~~~~~~~~~~~ Link: https://github.com/KSPP/linux/issues/278 Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kees Cook --- drivers/platform/chrome/cros_ec_vbc.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/platform/chrome/cros_ec_vbc.c b/drivers/platform/chrome/cros_ec_vbc.c index c859c862d7ac..b5a584f5469a 100644 --- a/drivers/platform/chrome/cros_ec_vbc.c +++ b/drivers/platform/chrome/cros_ec_vbc.c @@ -20,10 +20,14 @@ static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj, struct device *dev = kobj_to_dev(kobj); struct cros_ec_dev *ec = to_cros_ec_dev(dev); struct cros_ec_device *ecdev = ec->ec_dev; - struct ec_params_vbnvcontext *params; struct cros_ec_command *msg; + /* + * This should be a pointer to the same type as op field in + * struct ec_params_vbnvcontext. + */ + uint32_t *params_op; int err; - const size_t para_sz = sizeof(params->op); + const size_t para_sz = sizeof(*params_op); const size_t resp_sz = sizeof(struct ec_response_vbnvcontext); const size_t payload = max(para_sz, resp_sz); @@ -32,8 +36,8 @@ static ssize_t vboot_context_read(struct file *filp, struct kobject *kobj, return -ENOMEM; /* NB: we only kmalloc()ated enough space for the op field */ - params = (struct ec_params_vbnvcontext *)msg->data; - params->op = EC_VBNV_CONTEXT_OP_READ; + params_op = (uint32_t *)msg->data; + *params_op = EC_VBNV_CONTEXT_OP_READ; msg->version = EC_VER_VBNV_CONTEXT; msg->command = EC_CMD_VBNV_CONTEXT;