ACK: [PATCH 2/5] bios32: ensure mmap'd memory is readable before accessing it

[Alex Hung]

On 2017-07-12 05:53 AM, Colin King wrote:
> From: Colin Ian King <colin.king at canonical.com>
> 
> We need to check we don't get SIGSEGV or SIGBUS errors when reading
> the mmap'd data before we try and access it. Use the fwts_safe_memread
> check on the data to sanity check these mappings.
> 
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
> ---
>   src/bios/bios32/bios32.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/src/bios/bios32/bios32.c b/src/bios/bios32/bios32.c
> index e7f086f2..330f05e3 100644
> --- a/src/bios/bios32/bios32.c
> +++ b/src/bios/bios32/bios32.c
> @@ -65,6 +65,11 @@ static int bios32_test1(fwts_framework *fw)
>   	}
>   
>   	for (i = 0; i < BIOS32_SD_REGION_SIZE; i+= 16) {
> +		const size_t size = sizeof(fwts_bios32_service_directory);
> +
> +		/* Is the region safe to read? */
> +		if (fwts_safe_memread(mem, size) != FWTS_OK)
> +			continue;
>   		if ((*(mem+i)   == '_') &&
>   		    (*(mem+i+1) == '3') &&
>   		    (*(mem+i+2) == '2') &&
> 

Acked-by: Alex Hung <alex.hung at canonical.com>