PACKET_RESERVE reserves headroom in memory mapped packet ring frames.
The value po->tp_reserve must is verified to be safe in packet_set_ring
if (unlikely(req->tp_frame_size < po->tp_hdrlen + po->tp_reserve))
and the setsockopt fails once a ring is set.
if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
return -EBUSY;
This operation does not take the socket lock. This leads to a race
similar to the one with PACKET_VERSION fixed in commit
84ac7260236a
("packet: fix race condition in packet_set_ring").
Fix this issue in the same manner: take the socket lock, which as of
that patch is held for the duration of packet_set_ring.
This bug was discovered with syzkaller.
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
CVE-2017-
1000111
(backported from email submission)
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
if (optlen != sizeof(val))
return -EINVAL;
- if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
- return -EBUSY;
if (copy_from_user(&val, optval, sizeof(val)))
return -EFAULT;
if (val > INT_MAX)
return -EINVAL;
- po->tp_reserve = val;
- return 0;
+ lock_sock(sk);
+ if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
+ ret = -EBUSY;
+ else {
+ po->tp_reserve = val;
+ ret = 0;
+ }
+ release_sock(sk);
+ return ret;
}
case PACKET_LOSS:
{