Am 06.11.2010 15:39, schrieb Vasiliy Kulikov:
> On Mon, Nov 01, 2010 at 10:14 +0100, walter harms wrote:
>>
>>
>> Vasiliy Kulikov schrieb:
>>> packet_getname_spkt() doesn't initialize all members of sa_data field of
>>> sockaddr struct if strlen(dev->name) < 13. This structure is then copied
>>> to userland. It leads to leaking of contents of kernel stack memory.
>>> We have to fully fill sa_data with strncpy() instead of strlcpy().
>>>
>>> The same with packet_getname(): it doesn't initialize sll_pkttype field of
>>> sockaddr_ll. Set it to zero.
>>>
>>> Signed-off-by: Vasiliy Kulikov <segooon@xxxxxxxxx>
>>> ---
>>> net/packet/af_packet.c | 3 ++-
>>> 1 files changed, 2 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
>>> index 3616f27..0856a13 100644
>>> --- a/net/packet/af_packet.c
>>> +++ b/net/packet/af_packet.c
>>> @@ -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 ? Would it hurt when some uses IFNAMSIZ here ?
Perhaps someone who know more about the network stack can figure out what is actualy done
with uaddr->sa_data.
looks like a can of worms.
In packet_bind_spkt() they will copy a char[15], obviously it is a real problem.
re,
wh
>> You can simply that part:
>>
>> memset(uaddr->sa_data, 0, IFNAMSIZ);
>> dev = dev_get_by_index_rcu(sock_net(sk), pkt_sk(sk)->ifindex);
>> if (dev)
>> strlcpy(uaddr->sa_data, dev->name, IFNAMSIZ);
>
> This will overflow uaddr->sa_data. Also I don't see any difficulty to
> fill the array only once.
>
>> you should send that as separate patch.
>> re,
>> wh
>>
>>
>>> rcu_read_unlock();
>>> @@ -1742,6 +1742,7 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
>>> sll->sll_family = AF_PACKET;
>>> sll->sll_ifindex = po->ifindex;
>>> sll->sll_protocol = po->num;
>>> + sll->sll_pkttype = 0;
>>> rcu_read_lock();
>>> dev = dev_get_by_index_rcu(sock_net(sk), po->ifindex);
>>> if (dev) {
>
> Thanks,
>
--
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
