diff options
| author | Willem de Bruijn <willemb@google.com> | 2017-09-26 12:19:37 -0400 |
|---|---|---|
| committer | Todd Kjos <tkjos@google.com> | 2018-02-28 15:04:43 -0800 |
| commit | c6f1a1837b1161764e8b0682e28189006c8f1b46 (patch) | |
| tree | b0ef3b9067aa11837c3825be14d54f11010a88f4 | |
| parent | 8551d1148080592095e4dadcb4420b3ba7a5743c (diff) | |
packet: in packet_do_bind, test fanout with bind_lock held
[ Upstream commit 4971613c1639d8e5f102c4e797c3bf8f83a5a69e ]
Once a socket has po->fanout set, it remains a member of the group
until it is destroyed. The prot_hook must be constant and identical
across sockets in the group.
If fanout_add races with packet_do_bind between the test of po->fanout
and taking the lock, the bind call may make type or dev inconsistent
with that of the fanout group.
Hold po->bind_lock when testing po->fanout to avoid this race.
I had to introduce artificial delay (local_bh_enable) to actually
observe the race.
Fixes: dc99f600698d ("packet: Add fanout support.")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/packet/af_packet.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 3f651ddbe9a5..7204f553ab64 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2668,13 +2668,15 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex, int ret = 0; bool unlisted = false; - if (po->fanout) - return -EINVAL; - lock_sock(sk); spin_lock(&po->bind_lock); rcu_read_lock(); + if (po->fanout) { + ret = -EINVAL; + goto out_unlock; + } + if (name) { dev = dev_get_by_name_rcu(sock_net(sk), name); if (!dev) { |