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 ?
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.
> 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,
> >
--
Vasiliy
--
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
