diff options
| author | Willem de Bruijn <willemb@google.com> | 2017-09-26 12:19:37 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-09-28 10:24:31 -0700 |
| commit | 4971613c1639d8e5f102c4e797c3bf8f83a5a69e (patch) | |
| tree | d7938c4f52b72eb98d9e0d5c229c805547a277f8 | |
| parent | 1579f678fb4397f9e439d2e373d4ade036c673b4 (diff) | |
| download | linux-4971613c1639d8e5f102c4e797c3bf8f83a5a69e.tar.bz2 | |
packet: in packet_do_bind, test fanout with bind_lock held
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>
| -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 d288f52c53f7..a10c2836465c 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3069,13 +3069,15 @@ 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) { |