ACK: [PATCH 1/5] dmi: dmicheck: ensure mmap'd SMBIOS data 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 SMBIOS 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/dmi/dmicheck/dmicheck.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
> 
> diff --git a/src/dmi/dmicheck/dmicheck.c b/src/dmi/dmicheck/dmicheck.c
> index 5f010f53..306a0088 100644
> --- a/src/dmi/dmicheck/dmicheck.c
> +++ b/src/dmi/dmicheck/dmicheck.c
> @@ -332,6 +332,12 @@ static void* dmi_table_smbios(fwts_framework *fw, fwts_smbios_entry *entry)
>   
>   	mem = fwts_mmap(addr, length);
>   	if (mem != FWTS_MAP_FAILED) {
> +		/* Can we safely copy the table? */
> +		if (fwts_safe_memread((void *)addr, length) != FWTS_OK) {
> +			fwts_log_info(fw, "SMBIOS table at %p cannot be read", (void *)addr);
> +			(void)fwts_munmap(mem, length);
> +			return NULL;
> +		}
>   		table = malloc(length);
>   		if (table)
>   			memcpy(table, mem, length);
> @@ -373,6 +379,12 @@ static void* dmi_table_smbios30(fwts_framework *fw, fwts_smbios30_entry *entry)
>   
>   	mem = fwts_mmap(addr, length);
>   	if (mem != FWTS_MAP_FAILED) {
> +		/* Can we safely copy the table? */
> +		if (fwts_safe_memread((void *)addr, length) != FWTS_OK) {
> +			fwts_log_info(fw, "SMBIOS table at %p cannot be read", (void *)addr);
> +			(void)fwts_munmap(mem, length);
> +			return NULL;
> +		}
>   		table = malloc(length);
>   		if (table)
>   			fwts_memcpy_unaligned(table, mem, length);
> 


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