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Subject: Re: [PATCH 1/4] platform/x86: simatic-ipc: add main driver for
 Siemens devices
To:     Henning Schild <henning.schild@siemens.com>,
        linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org,
        platform-driver-x86@vger.kernel.org, linux-watchdog@vger.kernel.org
Cc:     Srikanth Krishnakar <skrishnakar@gmail.com>,
        Jan Kiszka <jan.kiszka@siemens.com>,
        Gerd Haeussler <gerd.haeussler.ext@siemens.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Mark Gross <mgross@linux.intel.com>,
        Pavel Machek <pavel@ucw.cz>
References: <20210302163309.25528-1-henning.schild@siemens.com>
 <20210302163309.25528-2-henning.schild@siemens.com>
From:   Hans de Goede <hdegoede@redhat.com>
Message-ID: <ed715381-016a-5bf7-3cdb-d340747c4498@redhat.com>
Date:   Thu, 4 Mar 2021 15:03:43 +0100
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Hi,

On 3/2/21 5:33 PM, Henning Schild wrote:

<snip>

> +static inline u32 simatic_ipc_get_station_id(u8 *data)
> +{
> +	u32 station_id = SIMATIC_IPC_INVALID_STATION_ID;
> +	int i;
> +	struct {
> +		u8	type;		/* type (0xff = binary) */
> +		u8	len;		/* len of data entry */
> +		u8	reserved[3];
> +		u32	station_id;	/* station id (LE) */
> +	} __packed * data_entry = (void *)data;
> +
> +	/* find 4th entry in OEM data */
> +	for (i = 0; i < 3; i++)
> +		data_entry = (void *)((u8 *)(data_entry) + data_entry->len);
> +
> +	/* decode station id */
> +	if (data_entry && data_entry->type == 0xff && data_entry->len == 9)
> +		station_id = le32_to_cpu(data_entry->station_id);
> +
> +	return station_id;
> +}
> +
> +static inline void
> +simatic_ipc_find_dmi_entry_helper(const struct dmi_header *dh, void *_data)
> +{
> +	u32 *id = _data;
> +
> +	if (dh->type != DMI_ENTRY_OEM)
> +		return;
> +
> +	*id = simatic_ipc_get_station_id((u8 *)dh + sizeof(struct dmi_header));
> +}

Please take dh->length into account here and make sure that you don't walk
past the end of the DMI tables during the parsing here.

Regards,

Hans


> +
> +#endif /* __PLATFORM_DATA_X86_SIMATIC_IPC_H */
>