Am 07.11.2010 13:06, schrieb Vasiliy Kulikov:
> On Sun, Nov 07, 2010 at 12:37 +0100, walter harms wrote:
>> Am 06.11.2010 15:39, schrieb Vasiliy Kulikov:
>>> On Mon, Nov 01, 2010 at 10:14 +0100, walter harms wrote:
>>>> Vasiliy Kulikov schrieb:
>>>>> @@ -1719,7 +1719,7 @@ static int packet_getname_spkt(struct socket *sock, struct sockaddr *uaddr,
>>>>> rcu_read_lock();
>>>>> dev = dev_get_by_index_rcu(sock_net(sk), pkt_sk(sk)->ifindex);
>>>>> if (dev)
>>>>> - strlcpy(uaddr->sa_data, dev->name, 15);
>>>>> + strncpy(uaddr->sa_data, dev->name, 14);
>>>>> else
>>>>> memset(uaddr->sa_data, 0, 14);
>>>>
>>>> if i understand the code correcly the max size for dev->name is IFNAMSIZ.
>>>
>>> For dev->name - IFNAMSIZ, for uaddr->sa_data - 14.
>>>
>>
>>
>> did not notice, since uaddr->sa_data should take dev->name this does no look very
>> clever. How is the size of sa_data defined ?
>
> Magic size...
>
> ~/linux/include/linux/socket.h:
>
> struct sockaddr {
> sa_family_t sa_family; /* address family, AF_xxx */
> char sa_data[14]; /* 14 bytes of protocol address */
> };
>
>
>> Would it hurt when some uses IFNAMSIZ here ?
>
so i should be more direct. the idea was :
char sa_data[IFNAMSIZ];
> If copy _to_ sa_data string of maximum IFNAMSIZ bytes - yes.
>
>
> In packet_getname_spkt() the output buffer is 128 bytes, so it doesn't
> really overflows anything. I don't think that *_getname() implementations
> don't know this.
>
>> Perhaps someone who know more about the network stack can figure out what is actualy done
>> with uaddr->sa_data.
>
> Yeah, also I wonder whether it is always NULL-terminated string or not.
>
>> looks like a can of worms.
>>
>>
>> In packet_bind_spkt() they will copy a char[15], obviously it is a real problem.
>
> No, packet_bind_spkt() copies 14-byte string into array of 15 bytes.
> The vice versa would be a bug.
>
ups your are right, wrong way around. it still does not look clever.
I have the feeling that the basic idea what to store the string with out \0.
according to this:
http://www.gnu.org/s/libc/manual/html_node/Address-Formats.html
It should work.
re,
wh
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