linux-kernel - Re: [char-misc-next 3/6] mei: bus: use sizeof of variable instead of struct type

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Message-ID: <cab66bcc-6b48-772e-9f16-41c1c076c42d@embeddedor.com>
Date:   Thu, 23 Jul 2020 11:55:11 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Tomas Winkler <tomas.winkler@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        linux-kernel@...r.kernel.org,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [char-misc-next 3/6] mei: bus: use sizeof of variable instead of
 struct type



On 7/23/20 09:59, Tomas Winkler wrote:
> There is a possibility of bug when variable type has changed but
> corresponding struct passed to the sizeof has not.
> 
> Cc: Gustavo A. R. Silva <gustavoars@...nel.org>
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>

Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Thanks
--
Gustavo

> ---
>  drivers/misc/mei/bus-fixup.c | 23 +++++++++++------------
>  drivers/misc/mei/bus.c       |  2 +-
>  2 files changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/misc/mei/bus-fixup.c b/drivers/misc/mei/bus-fixup.c
> index 910f059b3384..07ba16d46690 100644
> --- a/drivers/misc/mei/bus-fixup.c
> +++ b/drivers/misc/mei/bus-fixup.c
> @@ -1,6 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0
>  /*
> - * Copyright (c) 2013-2019, Intel Corporation. All rights reserved.
> + * Copyright (c) 2013-2020, Intel Corporation. All rights reserved.
>   * Intel Management Engine Interface (Intel MEI) Linux driver
>   */
>  
> @@ -159,17 +159,17 @@ static int mei_osver(struct mei_cl_device *cldev)
>  static int mei_fwver(struct mei_cl_device *cldev)
>  {
>  	char buf[MKHI_FWVER_BUF_LEN];
> -	struct mkhi_msg *req;
> +	struct mkhi_msg req;
> +	struct mkhi_msg *rsp;
>  	struct mkhi_fw_ver *fwver;
>  	int bytes_recv, ret, i;
>  
>  	memset(buf, 0, sizeof(buf));
>  
> -	req = (struct mkhi_msg *)buf;
> -	req->hdr.group_id = MKHI_GEN_GROUP_ID;
> -	req->hdr.command = MKHI_GEN_GET_FW_VERSION_CMD;
> +	req.hdr.group_id = MKHI_GEN_GROUP_ID;
> +	req.hdr.command = MKHI_GEN_GET_FW_VERSION_CMD;
>  
> -	ret = __mei_cl_send(cldev->cl, buf, sizeof(struct mkhi_msg_hdr),
> +	ret = __mei_cl_send(cldev->cl, (u8 *)&req, sizeof(req),
>  			    MEI_CL_IO_TX_BLOCKING);
>  	if (ret < 0) {
>  		dev_err(&cldev->dev, "Could not send ReqFWVersion cmd\n");
> @@ -188,7 +188,8 @@ static int mei_fwver(struct mei_cl_device *cldev)
>  		return -EIO;
>  	}
>  
> -	fwver = (struct mkhi_fw_ver *)req->data;
> +	rsp = (struct mkhi_msg *)buf;
> +	fwver = (struct mkhi_fw_ver *)rsp->data;
>  	memset(cldev->bus->fw_ver, 0, sizeof(cldev->bus->fw_ver));
>  	for (i = 0; i < MEI_MAX_FW_VER_BLOCKS; i++) {
>  		if ((size_t)bytes_recv < MKHI_FWVER_LEN(i + 1))
> @@ -329,16 +330,14 @@ static int mei_nfc_if_version(struct mei_cl *cl,
>  
>  	WARN_ON(mutex_is_locked(&bus->device_lock));
>  
> -	ret = __mei_cl_send(cl, (u8 *)&cmd, sizeof(struct mei_nfc_cmd),
> -			    MEI_CL_IO_TX_BLOCKING);
> +	ret = __mei_cl_send(cl, (u8 *)&cmd, sizeof(cmd), MEI_CL_IO_TX_BLOCKING);
>  	if (ret < 0) {
>  		dev_err(bus->dev, "Could not send IF version cmd\n");
>  		return ret;
>  	}
>  
>  	/* to be sure on the stack we alloc memory */
> -	if_version_length = sizeof(struct mei_nfc_reply) +
> -		sizeof(struct mei_nfc_if_version);
> +	if_version_length = sizeof(*reply) + sizeof(*ver);
>  
>  	reply = kzalloc(if_version_length, GFP_KERNEL);
>  	if (!reply)
> @@ -352,7 +351,7 @@ static int mei_nfc_if_version(struct mei_cl *cl,
>  		goto err;
>  	}
>  
> -	memcpy(ver, reply->data, sizeof(struct mei_nfc_if_version));
> +	memcpy(ver, reply->data, sizeof(*ver));
>  
>  	dev_info(bus->dev, "NFC MEI VERSION: IVN 0x%x Vendor ID 0x%x Type 0x%x\n",
>  		ver->fw_ivn, ver->vendor_id, ver->radio_type);
> diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
> index f476dbc7252b..a6dfc3ce1db2 100644
> --- a/drivers/misc/mei/bus.c
> +++ b/drivers/misc/mei/bus.c
> @@ -931,7 +931,7 @@ static struct mei_cl_device *mei_cl_bus_dev_alloc(struct mei_device *bus,
>  	struct mei_cl_device *cldev;
>  	struct mei_cl *cl;
>  
> -	cldev = kzalloc(sizeof(struct mei_cl_device), GFP_KERNEL);
> +	cldev = kzalloc(sizeof(*cldev), GFP_KERNEL);
>  	if (!cldev)
>  		return NULL;
>  
>