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.
> 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
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