From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CAB0FC2DE for ; Thu, 30 Mar 2023 07:01:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78482C433EF; Thu, 30 Mar 2023 07:01:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1680159686; bh=H3toqFQVNcpuGUTVQatxSq9QUFu7uhOw9AGmIacnjMA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RbIfwNUYo6lNqcJnUmsRHqjAeehV12pNlEYbDi4Cu1UYYibz0ZSoqLAXT3AA8fpJI hbSxynNc2t0S8Fmqbdg951w0p8NeQX8DjcZRiBWMbV66HyCLOL9BWUquWB07w9cDS3 8bK9seUy7ecfj152HB8nBW5OVSrOZ9s6QqHFiiKqNT+7OFs2VnpoBeUGGrbJeX3pRO MSJJiwnRP+KJMzpAqD6vdrivZuv5kUIcyvzoLhGw0q2h6raXKXsQOE1fvO208rNHkA b7k0hf4Yxf9+U9YBPhDQtEceMFPlYXw1Bofp+9IdQSTVmI7JxW6D931MM7jQ4O/QPW xK+mibakT364A== Date: Thu, 30 Mar 2023 15:01:23 +0800 From: Tzung-Bi Shih To: "Gustavo A. R. Silva" Cc: Benson Leung , Guenter Roeck , chrome-platform@lists.linux.dev, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH][next] platform/chrome: Fix -Warray-bounds warnings Message-ID: References: Precedence: bulk X-Mailing-List: chrome-platform@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Mar 29, 2023 at 07:54:02PM -0600, Gustavo A. R. Silva wrote: > 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). It doesn't make sense to me. See comments below. > 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); > | ~~~~~~~~~~~~ Please trim the commit message a bit and try to wrap at 75 columns as [1] suggested. [1]: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#the-canonical-patch-format > @@ -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; I don't see a good reason to partially allocate memory here. Perhaps, just let `para_sz = sizeof(struct ec_params_vbnvcontext)`? If it also makes sense to you, please remove the comment "NB: we only..." as well.