[coreboot] [PATCH] flashrom: Improve coreboot image detection heuristic
Stefan Reinauer
stepan at coresystems.de
Thu Jul 3 16:37:40 CEST 2008
Carl-Daniel Hailfinger wrote:
> Improve coreboot image detection heuristic in flashrom. It's not
> absolutely perfect, but the likelihood of this check to fail is
> 0.000000000000000000000000013 (1.3*10^-26) which is good enough for me.
>
I think at some point we should go to a better concept of doing things,
but it seems what you are saying is that your code will probably not
fail on any bios that has been developed to date, as I doubt it is more
than 10^26 bioses.
Acked-by: Stefan Reinauer <stepan at coresystems.de>
> Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>
>
> Index: flashrom-tmp1/layout.c
> ===================================================================
> --- flashrom-tmp1/layout.c (Revision 3407)
> +++ flashrom-tmp1/layout.c (Arbeitskopie)
> @@ -21,6 +21,7 @@
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> +#include <ctype.h>
> #include <stdint.h>
> #include "flash.h"
>
> @@ -57,7 +58,18 @@
> walk--;
> }
>
> - if ((*walk) == 0 || ((*walk) & 0x3ff) != 0) {
> + /*
> + * Check if coreboot last image size is 0 or not a multiple of 1k or
> + * bigger than the chip or if the pointers to vendor ID or mainboard ID
> + * are outside the image of if the start of ID strings are nonsensical
> + * (nonprintable and not \0).
> + */
> + if ((*walk) == 0 || ((*walk) & 0x3ff) != 0 || *walk > size ||
> + *(walk - 1) > size || *(walk - 2) > size ||
> + (!isprint((const char *)(bios + size - *(walk - 1))) &&
> + ((const char *)(bios + size - *(walk - 1)))) ||
> + (!isprint((const char *)(bios + size - *(walk - 2))) &&
> + ((const char *)(bios + size - *(walk - 2))))) {
> printf("Flash image seems to be a legacy BIOS. Disabling checks.\n");
> mainboard_vendor = def_name;
> mainboard_part = def_name;
>
>
>
--
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