Messages in this thread | | | Date | Sat, 6 Nov 2010 17:39:11 +0300 | From | Vasiliy Kulikov <> | Subject | Re: [PATCH 2/3] net: packet: fix information leak to userland |
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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@gmail.com> > > --- > > 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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