Re: [Orinoco-devel] [PATCH 1/2] orinoco: validate firmware header

[Andrey Borzenkov <arvidjaar@mail.ru>]

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On 20 of February 2009 02:46:26 David Kilroy wrote:
>
> +static const char *fw_err[] = {
> +	"image too small",
> +	"format not recognised",
> +	"bad headersize",
> +	"bad block offset",
> +	"bad PDR offset",
> +	"bad PRI offset",
> +	"bad compat offset"
> +};
> +
>  /* Structure used to access fields in FW
>   * Make sure LE decoding macros are used
>   */
> @@ -43,6 +53,32 @@ struct orinoco_fw_header {
>  	char signature[0];      /* FW signature length headersize-20 */
>  } __attribute__ ((packed));
>
> +/* Check the range of various header entries */
> +static int validate_fw(const struct orinoco_fw_header *hdr, size_t
> len) +{
> +	u16 hdrsize;
> +
> +	if (len < sizeof(*hdr))
> +		return 1;
> +	if (memcmp(hdr->hdr_vers, "HFW", 3) != 0)
> +		return 2;
> +
> +	hdrsize = le16_to_cpu(hdr->headersize);
> +	if (hdrsize > len)
> +		return 3;
> +	if ((hdrsize + le32_to_cpu(hdr->block_offset)) > len)
> +		return 4;
> +	if ((hdrsize + le32_to_cpu(hdr->pdr_offset)) > len)
> +		return 5;
> +	if ((hdrsize + le32_to_cpu(hdr->pri_offset)) > len)
> +		return 6;
> +	if ((hdrsize + le32_to_cpu(hdr->compat_offset)) > len)
> +		return 7;
> +
> +	/* TODO: consider adding a checksum or CRC to the firmware format
> */ +	return 0;
> +}


I am afraid this can easily go off sync. Any reason those messages 
cannot be printed inline in validate_fw()?

Otherwise what about

#define FW_ERR_OK	0
#define FW_ERR_TOO_SMALL 1
...
static const char *fw_err[] = {
	[FW_ERR_TOO_SMALL] = "image too small",
...

	if (len < sizeof(*hdr))
		return FW_ERR_TOO_SMALL;
...
	return FW_ERR_OK;

?

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