Mauro Carvalho Chehab wrote:
> Stefan Richter wrote:
>
>> The Digital Everywhere firmware have the shortcoming that ca_info_enq and
>> ca_info are not supported. This means that we can never retrieve the correct
>> ca_system_id to present in the CI message CA_INFO. Currently the driver uses
>> the application id retrieved using app_info_req and app_info, but this id
>> only match the correct ca_system_id as given in ca_info in some cases.
>> This patch adds a parameter to the driver in order for the user to override
>> what will be returned in the CA_INFO CI message. Up to four ca_system_ids can
>> be specified.
>> This is needed for users with CAMs that have different manufacturer id and
>> ca_system_id and that uses applications that take this into account, like
>> MythTV.
>
> This seems an ugly workaround. The better seems to patch MythTV to accept a
> different
> CAM.
Ugly it is, for sure. Can't comment on application-level solutions; if
thats the proper layer at which to address this, then that would be
preferable of course.
>> +static int num_fake_ca_system_ids;
> ...
>> + for (i = 0; i < num_fake_ca_system_ids; i++) {
>> + app_info[4 + i * 2] =
>> + (fake_ca_system_ids[i] >> 8) & 0xff;
> ...
>
> NAK. If someone put an arbitrary high value for num_fake_ca_system_id's, it
> will write outside
> the app_info array space, as the num_fake_ca_system_ids is not validated
> against the size
> of app_info.
That's what I thought at first look at the patch too, but then I noticed
that inlcude/linux/moduleparam.h and kernel/params.c properly track
kparam_arry.max = ARRAY_SIZE(array).
http://lxr.linux.no/#linux+v2.6.33/include/linux/moduleparam.h#L62
http://lxr.linux.no/#linux+v2.6.33/include/linux/moduleparam.h#L213
http://lxr.linux.no/#linux+v2.6.33/kernel/params.c#L351
http://lxr.linux.no/#linux+v2.6.33/kernel/params.c#L296
So no danger here.
> Also, it makes no sense a negative value for this parameter.
I already posted an updated version of the patch which correctly defines
num_fake_ca_system_ids as an unsigned long.
--
Stefan Richter
-=====-==-=- --== --==-
http://arcgraph.de/sr/
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