Am 01.03.2012 14:03, schrieb Pablo Neira Ayuso:
> On Thu, Mar 01, 2012 at 04:15:05PM +0530, santosh prasad nayak wrote:
>> Hi Pablo.
>>
>> copy_to_user( dest, source, length)
>>
>> Normally, 'length' is equal to 'sizeof (source) '.
>>
>> In this case "length" = 32
>> "sizeof(source)" = 29.
>>
>> Is it intentional ?
>
> ebtables expects 32 bytes names.
>
>> Won't it copy extra 3 bytes of kernel data to userspace ?
>
> You're right. We have to copy 29 bytes but we have to fill the
> remaining bytes with zeroes. I think something like:
>
> char name[EBT_FUNCTION_MAXNAMELEN] = {};
>
> /* user-space ebtables expects 32 bytes-long names, but xt_match uses
> * 29 bytes for that. */
> sprintf(name, "%s", m->u.match->name);
> if (copy_to_user(hlp, name, EBT_FUNCTION_MAXNAMELEN))
> ...
>
it may be better to use kstrncpy() here. kstrncpy will fill remaining
space with 0. now you are using char name[EBT_FUNCTION_MAXNAMELEN] later
this may change, better safe than sorry.
re,
wh
> will resolve this issue.
>
> Would you resend a new patch?
> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
--
To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
