[Bridge] [PATCH 1/3] netfilter: Fix copy_to_user too small size parametre.

[santosh prasad nayak]

Thanks Pablo for clarification.
I will resend the patch.


regards
santosh

On Thu, Mar 1, 2012 at 6:33 PM, Pablo Neira Ayuso <pablo at netfilter.org> wrote:
> 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))
> ...
>
> will resolve this issue.
>
> Would you resend a new patch?