diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-02-14 09:03:51 -0800 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2017-05-20 19:00:37 +0200 |
| commit | 2fb6ab951ff946a879d9128a81b9b960ffe511bd (patch) | |
| tree | ca939a14eaa7109bb6858be56596ae84488c5f90 | |
| parent | e81aa7c21c7b9f30998519db6d63056b42544867 (diff) | |
packet: fix races in fanout_add()
[ Upstream commit d199fab63c11998a602205f7ee7ff7c05c97164b ]
Multiple threads can call fanout_add() at the same time.
We need to grab fanout_mutex earlier to avoid races that could
lead to one thread freeing po->rollover that was set by another thread.
Do the same in fanout_release(), for peace of mind, and to help us
finding lockdep issues earlier.
[js] no rollover in 3.12
Fixes: dc99f600698d ("packet: Add fanout support.")
Fixes: 0648ab70afe6 ("packet: rollover prepare: per-socket state")
Change-Id: I0418252031431ab0f17c5a33073257d2c3106144
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | net/packet/af_packet.c | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 4264e5c01..4be79ae0a 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1311,13 +1311,16 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) return -EINVAL; } + mutex_lock(&fanout_mutex); + + err = -EINVAL; if (!po->running) - return -EINVAL; + goto out; + err = -EALREADY; if (po->fanout) - return -EALREADY; + goto out; - mutex_lock(&fanout_mutex); match = NULL; list_for_each_entry(f, &fanout_list, list) { if (f->id == id && @@ -1373,17 +1376,16 @@ static void fanout_release(struct sock *sk) struct packet_sock *po = pkt_sk(sk); struct packet_fanout *f; - f = po->fanout; - if (!f) - return; - mutex_lock(&fanout_mutex); - po->fanout = NULL; + f = po->fanout; + if (f) { + po->fanout = NULL; - if (atomic_dec_and_test(&f->sk_ref)) { - list_del(&f->list); - dev_remove_pack(&f->prot_hook); - kfree(f); + if (atomic_dec_and_test(&f->sk_ref)) { + list_del(&f->list); + dev_remove_pack(&f->prot_hook); + kfree(f); + } } mutex_unlock(&fanout_mutex); } |